training manua
TRANSCRIPT
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Training Manual on GIS for Land Information
Management Using ArcGIS 10 to
MU_CoDANR Staffs
November 2014
Mekelle, Ethiopia
Section I: Getting Started into ArcGIS
1. Exploring in Arc Catalog
Arc Catalog lets you explore and manage your data. After connecting to your data, use the
Catalog to explore its contents. When you find the data you want to use, you can add it to a
map. Often, when you get data for a project, you can’t use it right away; you may need to
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change its projection or format, modify its attributes, or link geographic features to attributes
stored in another table. When the data is finally ready, you should document its contents and
the changes you have made. These data management tasks can all be accomplished using
tools that are available in the Catalog.
The ArcCatalog application provides a catalog window that is used to organize and manage
various types of geographic information for ArcGIS for Desktop.
ArcCatalog organizes these contents into a tree view that you can work with to organize your
GIS datasets and ArcGIS documents, search and find information items, and to manage them.
ArcCatalog presents this information in a tree view and allows you to select a GIS item, view
its properties, and to access tools to operate on the selected item
ArcCatalog is used to:
Organize your GIS contents
Manage geodatabase schemas
Search for and add content to ArcGIS applications
Document your contents
Manage GIS servers
Manage standards-based metadata
Starting Arc Catalogue:
The first step to explore in Arc Catalog is how to open the program. To open Arc Catalog go
the start menu on your computer and find the ArcGIS program tab. Open the ArcGIS folder
and click on Arc Catalog. The following path symbols for moving through files may be used
in the lessons.
*** To access ArcCatalog, click Start Programs ArcGIS ArcCatalog
Components of Arc Catalogue
When ArcCatalog starts, the main menu and the standard Toolbar appear by default. Toolbars
are areas in the interface of ArcGIS with buttons that activate various features and functions.
Study the following screenshot and relate it with the ArcCatalog you have opened
Geographic Toolbar
Standard Toolbar
Main Menu Toolbar
Location Toolbar
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Look in a folder connection
When you select a folder connection in the Catalog tree, the Contents tab lists the items it
contains. Unlike Windows Explorer, the Catalog doesn’t list all files stored on disk; a folder
might appear empty even though it contains several files. Folders containing geographic data
sources have a different icon to make your data easier to find.
Look in a folder connection and locating the training folder in your catalog.
1. Click a folder connection in the Catalog tree. The items it contains appear in the
Contents tab.
2. Expand the sign of the D drive in the Catalog tree
3. Look for D drive and “MU_GIS\INTRODUCTION” folder and click on it
Contents
/Preview tool
Bar
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4. Click ok
Result: Now you should look the folder containing the training data for this part listed in the
catalog tree as follows
Exploring and Recognizing Different Types of GIS data base in Arc Catalogue
In this part you are going to practice how to explore different types of GIS data base in
ArcCatalog. You are also expected to recognize the different types of GIS data base
compatible with ArcGIS software.
Exploring GIS data bases in ArcCatalog:
Here you will see the contents of the ArcCatalog folder contained in the
“D\MU_GIS\INTRODUCTION” folder
1. Expand the plus sign behind the D:\MU_GIS\INTRODUCTION\ArcCatalog
2. Expand the folder “Tigray”
Result= you can look at the contents of the folder “ArcCatalog” in the preview window of
ArcCatalog
Exploring Data set using the Contents tab
When you select items, such as folders or Geodatabase in the Catalog tree, the Contents tab
lists the items they contain. To change the appearance of the Contents list, use the appropriate
buttons on the Standard toolbar.
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Explore the contents of the ArcCatalog folder:
Each type of geographic data has its own set of icons in the Catalog. The Tigrayfolder
contains a file geodatabase, shapefile, raster datasets, and dataset. These are some of the
methods in which geographic data is stored in the ArcGIS environment.
A. Double-click the D:\MU_GIS\INTRODUCTIONconnection in the Catalog tree.
B. Click the Arc Catalogue/Tigray folder in the Catalog tree.
C. Click the Large Icons button and look at the different types of Geographic data
bases in the preview window
D. Click the List button
E. Click the detail button
In doing all of these steps; you can observe the change in the appearance of the selected data
in the preview window of Arc catalog.
Identifying the Appearance of Different Types of data bases
Shapefiles: are vector systems of storing geographic datasets in the Arc GIS software: to see
the appearance of sahpefiles follow the following procedures.
A. Connect to D:\MU_GIS\INTRODUCTION\ArcCatalog\Tigray
B. Click on the Tigray folder. The green icons ordered inside the arc Catalog folder are
Shapefiles
Personal Geodatabase: Personal Geodatabase is a database that stores geographic
information. The concept “Geodatabase” can be simply explained as a container (database)
that stores data. You can see two feature classes in the Geodatabase (roads and buildings).
To see what it looks like a geodatabase, go through the following steps.
A. Connect to D:\MU_GIS\INTRODUCTION\ArcCatalog\Tigray
B. The “TigrayFeatures” file format and its featurs is a Geodatabase
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Featuredataset: the feature classes that share the same geographic
extent and coordinate system will be grouped together in a Feature
Dataset.
Feature classes are collections of geographic features that share the
same geometry type (point, line or polygon), attributes and spatial
reference.
Follow the following exercises to better know about Personal
Geodatbases, feature data set and Feature Classes
A. Click on Basic Features in TigrayFeatures.mdb file in the catalogue tree
B. Explore all the contents of Basic Features in TigrayFeatures.mdb by clicking on the plus
sign in front of it
C. Expand each of the contents of the data base and look at the feature classes in each of the
feature datasets
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Exploring in ArcMap
Introduction
In this part of the training, you will be working with Arc Map. The data for respective
activities are stored in the directories guided by this manual.
Uses of Arc Map
ArcMap is the tool for creating, viewing, querying, editing, composing, and publishing maps.
ArcMap is where you create maps and access most of the ArcGIS functionality. It helps to
display data, make selections, analyse data, manipulate data, create data, assign symbols and
produce map.
Starting ArcMap
You can launch ArcMap in several ways. If you are in ArcCatalog, click on the “Launch
ArcMap” button. Alternatively, go to the start menu, ArcGIS, and ArcMap or double-click on
a desktop icon (if you created one).
The Arc Map interface
When you launch the Arc Map in either of the afore stated methods, you will see the different
components of the Arc Map interface.
ArcMap is made up of many different windows and (dock-able) toolbars that you can resize
and move around so don’t be surprised if ArcMap looks slightly different each time you open
it. The window that lists your map layers is the table of contents; the window that shows your
map is the map display. You can close the table of contents by clicking on the “x” and resize
it by holding your cursor over the right edge until your cursor changes to a two-headed arrow.
Left-click and drag the edge to resize this window. To move one of your toolbars, left click on
the end (top or left), hold down, and move to a new location.
Adding Data
Table of
contents Map display
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If ArcMap is open, you will notice it looks like ArcCatalog except the data tree is replaced by
the Layers window in ArcMap. The layers window is where different GIS data layers are
displayed and organized. To understand this window, try adding the shape file of
KedamayWeyane sub city named “Kedamay_Weyane_Sub_City_Block.shp”. Click the add
icon in the standard button .
a. In the add data dialogue box Click the dropdown arrow and select D
b. Double Click MU_GIS\
c. Double click on the Arc GIS Folder
d. Click on the Kedamay_Weyane_Sub_City_Block.shp
e. Click on the add button.
Now the map with the blocks in KedamayWeyane sub city will be displayed. And the total
direction OF YOUR DIRECTORY will be
(D:\MU_GIS\ArcGIS\Kedamay_Woyane_Sub_City_Block.shp)
Customizing the Arc Map Interface
ArcMap is made up of many different windows and (dock-able) toolbars that you can resize
and move around so don’t be surprised if ArcMap looks slightly different each time you open
it.
Adding Tools and Toolbars
Different ArcMap applications may have application-specific toolbars. A toolbar can be made
visible (activated) or hidden (de-activated). The position of the toolbars within the interface is
flexible; they can float on the desktop and you can reposition them at any time. Alternatively
the toolbars can be docked to any side of the Arc Map window.
In order to activate other toolbars go to
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● Customize, then toolbars and you will get many toolbars for your specific use.
Alternatively,
●Left-click anywhere outside of the table of contents or map display, then many tools
will be displayed. You can choose any of the toolbars you want to add.
Opening ArcToolbox
Arc Toolbox contains the ArcGIS Spatial Analyst extension makes nearly 170 Geoprocessing
tools available to you, grouped into toolsets of related functionality for ease of access.
In any ArcGIS, for Desktop application, you can open the Arc Tool box window with the
Show/Hide ArcToolbox Window button found on the standard toolbar or by clicking
Geoprocessing>ArcToolbox.
Working with Catalog Window
The Catalog window provides an integrated and unified tree view of all the data files,
databases, and ArcGIS for Server documents available to you. The main menu of the Catalog
window has tools for navigating to common locations such as your map's Home folder and
the default geodatabase. In ArcGIS, you can interactively dock and retract windows against
the sides of the application window and slide them open as you need them. Retracting the
Catalog window enables you to have more of your application window devoted to your map
display.
Opening the Catalog window
If the Catalog window is not visible in ArcMap, you can open it in the following ways
1. Click the Catalog button on the Standard toolbar or by clicking
Windows>Catalog on the main menu. Click the pushpin to hold the Catalog window
open. You can close the Catalog window by clicking the X in the upper right
corner.
Connecting to the Working Directory in the Catalogue Tree
In the following activities you are going to connect to the folder containing the training data
A. Activate the catalog tree if it is not activated
B. Click on the connect to folder icon
C. In the connect to folder dial box window click on Computer
D. Use the drop down arrow and proceeded to D
E. Click on the drop down arrow and look for your working directory
D:\MU_MU_GIS
F. Select “D:\MU_GIS” folder
G. Click on Arc GIS folder and the Ok
• Now you can see your working directory listed in the catalogue window as follows
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Adding Data in Arc Map from the Catalogue Window
You can add and look the data stored in the respective folders pointed in the catalog tree in
the Arc Map display window
1. Click on the Kedamay_Weyane_sub_city_block file in the Cataloge window
2. Drag the file and put it in the Table of Contents Window
3. You can add the rest of the data set in the same way and explore their attributes
Working with the Table of Contents
The table of contents lists all the layers on the map and shows what the features in each layer
represent. The map's table of contents helps you manage the display order of map layers and
symbol assignment, as well as set the display and other properties of each map layer.
Making Logical Arrangement of Data in the Table of Contents
The arrangement of the layers in table of contents must be logical (the smallest features at the
top and the largest at the bottom, so that the largest feature may not cover the smallest
feature).
To do that,
A. Click on the Road_Network
B. Drag them at the bottom of all other layers
Now, because roads are linear features, they are covered by the largest
Mekelle_Administrative_boundary layer, they are invisible in the display window, so you
should have to return them to their original location as follows
A. Click on Road_Networks layer
B. Drag and drop at the top of other layer
Now you can look the Road_networks layer visible in the display window. Try to practice
rearranging the other layers in the same way.
Turning on and Off layers
With List by Visibility, you have visual cues to indicate the layer's visibility. Each type of
layer has its own icon, and the symbol is either colored to indicate the layer is on or gray
when it is not, so you can quickly look at the icon to determine whether a layer is visible.
Visible—the layer is turned on:
Not visible—the layer is turned off
Try to practice changing the visibility of the layers by checking and unchecking the box next
to it.
View the properties of a layer
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a. In the table of contents, double-click on the name of a layer or right-click on the
layer’s name and click Properties. The layer properties window will be opened.
b. In this dialog window you can set a number of properties for the selected layer.
c. When finished, press the Cancel button.
View the properties of the data frame
A data frame in ArcMap contains one or more layers; it defines the geographic extent,
coordinate system and other display properties of the layers in ArcMap. You can see the
name of a data from displayed at the top in the table of contents. By default, when a map is
created, the data frame is called “Layers”, but it can be changed.
A dataset has at least one data frame, but can be represented in more than one data frame; you
can add data frames to a map, each containing its own set of layers. In the Data View, you
can only display one data frame at the time. In the Layout View, however, you can place
different data frames at different positions next to each other on a page.
• In the table of contents, right-click on the name of the data frame: Layers and
select Properties, or double-click on the name (layers).
• Click the “General” tab: You see that the name of the data frame is called “Layers”.
You can Change this name
• Notice that the map units and display units for this map are “unknown”. You can
assign theunits by selecting from the drop-down menu.
• Click other tabs to see different kinds of properties.
• When finished, click OK to close the data frame properties window.
Frame name
Units
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Removing Layers
If you don’t want the layer to be found in Arc Map you can remove it by right click on the
layer to be removed and click on the remove option.
Exploring the Data Set
You can explore the data sets in Arc Map using the Tools toolbar.
Interactive Zoom in/out
There are several tools available for zooming in and out of your map. The continuous zoom
tool gives you the greatest amount of control.
A. Click on the zoom in/out button
B. Then left click on your map and hold down the mouse button, and
C. Move your mouse away from you to zoom in and towards you to zoom out
The fixed zoom in/fixed zoom out tools work like the zoom tools when you click them rather
than draw a box. Each time you click, you will zoom in or out a fixed amount.
Panning
This helps to explore the map in zoomed level
A. Click on the pan button
B. Left-click on your map display and hold the mouse button down
C. Shift your map, your extent (amount zoomed in or out) stays the same while your
map moves.
Full extent
The full extent button will zoom in or out so that all of your active (checked) map layers can
be viewed. You can also zoom in to a single layer by right clicking on the layer in the table of
contents and choosing “zoom to layer.”
Identify features
This helps to identify about the feature. It tells all the existing information about the feature
A. Click the Identify button on the Tools toolbar.
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B. The Identify window pops up with no information on the information table.
C. In the map display window, click on a feature (e.g. in the
Road_networks) to view information about it.
D. After identifying features, close the Results window.
Previous/Next
The previous extent buttons allow you to return to the extent you had before using
one of the zoom tools. The next extent button allows you to jump forward an extent (after you
have used the previous extent button).
Working with Attribute Table
GIS data basses often contain two types of databases, such as Spatial data and Attribute.
Spatial data is a data type containing the location of Geographic features. Attribute tables
provide descriptive information for the respective spatial features, which are often attached
with the spatial databases.
Opening and viewing Attribute Table
Follow the following steps to know and practice more about attribute tables
A. In the table of contents, right-click on the Mekelle_Administrative_Boundary
Layer to see the options menu
B. Click Open Attribute Table.
C. The attribute table opens, and you see attributes of the Administration in the
columns.
D. Look for the each of the colomns and observe what type of information is
contained in each of the columns
E. Close the attribute table of Mekelle_Administrative_Boundarylayer and open
attribute tables of some other
Exploring Field Properties
ArcMap has functionalities to enable you extracting useful information from the attribute
tables of GIS data basses. Go through the following procedures
A. Open the attribute tables of Mekelle_Administrative_Boundary layer
B. Right Click on the Top raw of the field Area
C. Click on Statistics
D. You can look at the different properties of the Statistical data of the different sub
cities of Mekelle city from the incoming window
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Selecting Features
Selecting features using attribute table:
A. Open the attribute table of Mekelle_Administrative_Boundary layer
B. Look under the “Sub_City” Field and find “KedamayWeyane” sub city
C. Click on the first column of the raw containing “KedamayWeyane”
D. Now you see “KedamayWeyane” highlighted in the ArcMap display
window
E. Practice selecting other “KedamayWeyane” using the same technique
Selecting Features Using the Selection Tool
The Selection tool allows you to select a certain geographical features without opening
the table of contents
A. If there is anything you have selected, clear it using the Clear Selected
button from the Tools menu
B. Click on the select icon in the Tools tool
C. Click in one of the features displayed in ArcMap to be selected
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D. If you want to Deselect the selected features; click the clear selected button
E. Practice selecting and deselecting features using Selection and Clear
selected Features tool.
Selecting by querying
It is also possible to select features by searching them with expressions
A. If there is anything you have selected Clear it using the Clear Selected features tool
B. From the main menu, point to Selections and click Select by attributes.
C. Click the layer dropdown arrow to select the layer “Mekelle_AdministrationZ_Boundary”
D. Click the method drop down arrow and click Create a new selection
E. Scroll down through the attribute options and search the field entitled “Sub_City”
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F. Double-click the field: “Sub_City”,
G. From the Dialog box containing Mathematical Signs clicks the sign,
H. Click the “get unique values” button
I. Look for the list of towns displayed in the Unique Values dialog box.
J. Scroll down and find Mekelle from the list of the towns
K. When you find, double click on the name Mekelle
L. Make sure that your selection query looks like the snap shoot below
M. If so, Click apply and OK
N. The selected city will be shown in the map display
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O. Close the Select by attributes window, close the attribute table and deselect the
selected feature.
Data Symbolization
A. Drawing a layer using a single symbol
• In the table of contents, double-click the layer Mekele_Adminstrative_Boundary
• In the Layer properties wndow, click the symbology tab
• Click Features – Single symbol
• Click the big symbol button to change the symbol characteristic
• In the symbol selector box, select a symbol from the big window. You can also
change some properties of the symbol, like colour and size. Try some possibilities
• After you created your symbol, click OK, then Apply. Now all the sub cities will be
displayed with the same colour.
• To close the layer properties box, click OK. The symbols of the villages in the table of
contents and in the map are changed according your specifications
• Repeat this process for all the other layers
Click here to go to
the symbol selector
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B. Drawing a layer showing unique values of records in a specific layer
If you want to display the different sub cities with different colors, follow the following steps.
•Right-click the layer Mekele_Adminstrative_Boundary and click on Open Attribute
Table
• Find which field can be used to display the Sub-cities. There might be different
attributes that uniquely identify each Mekele_Adminstrative_Boundary
• Close the attribute table
• In the table of contents, double-click the layer name Mekele_Adminstrative_Boundary
• In the layer properties window, click the symbology tab
• Click categories – Unique values.
• In the Value Field drop-down box, select the field “Sub_city”
• Click on Add All Values. You will see a list of the Sub cities in Mekelle
• Switch off the checkbox next to “all other values”, because there are no other
values
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• If you want to change the symbol (such as color) of one of the Sub-Cities, you can
double-click on the polygon symbol of the Sub_City.
• Or you can also go to the Color Rump on the Layer Properties window to change
for all the Sub_Cities
• Click OK when finished, the Sub_cities will be shown differently
• Save the map: Click on File then Save
Switching from Data view to Layout view
• Select the Layout View option from the view menu
• Alternatively, click the Layout View button in the toolbar at the bottom of the Map
window
• Note that you can always switch back to Data View, using the Data View option
Working with Lay outs
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The page setup on which you will do your maps has an important role in making your maps
more visible. So try to choose the appropriate page setups either from portrait and Landscape.
The choice will depends up on the shape of your data to be mapped.
A. Right click in the Arc map environment outside of the Layout view
B. Proceed to Page and Print Setup; and do the following arrangements:
a. Click on the drop down arrow in front of Size and select A3 as size
paper( the choice of paper sixe orientation will depend up on the scale
of the map to be produced)
b. In the orientation option click on Portrait (since it best visualizes the
map of Mekelle)
When you change the paper size, the layout frame becomes reduced and placed at the center
of the layout view, which means that you have more unused paces which will potentially
enlarge the visibility of the map elements. To do so,
A. Select the map frame by clicking on it
B. By using the arrows of the frame, drag the edge of the layout view to be
within the limited boundary
C. Zoom in the Map layer to the extent that the boundary of the map best fits to the
margins of the data frame
Symbolizing the Layers
Symbolizing Polygon Layers:
Following this you will practice Categorizing the Sub cities found within Mekelle in to
different colors
A. Right click on Mekelle_ Administration_Boundary Layer
B. Click on Properties Symbology
C. At the right of the Symbology dialog box, click on Categories and then unique
values
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D. Click on the Drop down arrow below the value field option and select
Sub_City as the attribute table used to classify the data
E. Click on Add All values at the bottom of the dialog box ( it will list out all the
layers found within Mekelle_Administrative_Boundary and assign a color
for each of them)
F. You can change the color combination by clicking on the color ramp option
G. Click Apply to change the color potions you have changed
H. Click OK when you finish
Symbolizing Lines Layer
A. Click on the line icon below the Road_NetworkLayer
B. Select Major roads Symbology from the set of listed symbols
C. You can edit the width and color of the line symbol using the color and width
option
D. Click OK when you finish
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Inserting Different Map Elements
You can add different types of map elements to the layout map using the Insert menu from the
main menu bar.
•Add a Title to a Map
A. Go to insert in the main menu
B. Click on Title
C. In the coming box write the title as “Sub Cities of Mekelle City”
D. Drag and put the title box on the top of the layout frame
• Add North Arrow
A. From the INSERT menu, select NORTH ARROW.
B. Choose a style you like, and click OK.
C. Move the north arrow by dragging with the mouse when the pointer changes
to a 4-way arrow.
•Add Scale Bar
A. From the INSERT menu, select Scale bar.
B. Choose a style you like (Alternate Scale bar 1 will be good) and click
OK
C. Drag the scale bar and place it at the bottom of the layout frame
D. Right click on the scale bar
E. You can readjust lots of scale map properties using this the Scale bar
properties
F. Put the division unit in Kilometers.
G. When you finish editing scale bars, click Apply and OK
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H. Check your map is look like the figure below. Do not worry about the
color, but look carefully about the content of your map and the figure.
• Add a Legend to a Map
A. From the INSERT menu, select LEGEND.
B. Click NEXT, and work your way through the wizard.
C. You can change any of these properties later, if you wish.
D. Drag and drop the Legend box at the bottom left corner of the map
frame You can resize the legend by using the resize icons found in the
corners of the legend box
• Add a Grid to a Map
A. Right Click on the Layout frame and click on Properties
B. Click on Grid in the Properties dialog box
C. Click on New Grid
D. Select Graticules select by Maps to be the type of Grid to be created
E. Click Next, next until you finish ( you can readjust this things latter if
you need)
F. Click Apply and Ok in the Data Frame Properties
G. If you need to make any modification for the Grids, you can right click
on the Layout data frame, proceeded to Grids
H. Properties
I. Here in the grid properties dialog box, you can readjust so many things
about the properties of the grid
J. Check your map is look like the figure below. Do not worry about the
color, but look carefully about the content of your map and the figure.
Exporting the Map
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If you need to insert the map in to a document or to print out it, or to transfer to another
person, you should have to export it in to a file format which can be easily opened other than
GIS packages. This file formats may be PDF, image file formats like tiff or JPEJ. So
exporting the map helps you to make your maps open in any computer which might not have
GIS software installed. It will also enables you to transfer your data for others who cannot
work with GIS software. Go through the following steps to export your maps
1. On the main menu click on file
2. Export map
3. Chose the destination folder you want to save your maps( you can chose Desktop)
4. Write Mekelle_Administration a file name
5. Use the Save as File type drop down arrow and select Tiff to be the type of file
format you will export your map
6. You can minimize or maximize the resolution of the output image using resolution
option
7. Click on Save when you finish
8. Open the map you have kept on the desk top
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Section II: Spatial Data Management and Editing using ArcGIS
1. Spatial Referencing
Map projection
If you want to produce a map of features on the Earth’s surface, you need to transform the
sphericalsurface to a flat map. This transformation from three-dimensional surface onto a two-
dimensional mapis called projection. Mathematical expressions convert data from the angular,
geographical coordinatesystem of a sphere to a linear, orthogonal projected coordinate system
of a flat map.
From the Earth’s surface to a 3D reference surface
First, a mathematical three-dimensional reference surface, which models the Earth’s physical
shape, hasto be defined: the ellipsoid. The ellipsoid is a smooth surface. The actual surface of
the Earth,represented by the ‘mean sea level’ (geoid), is not smooth. This means that there are
alwaysdiscrepancies between the ellipsoid and the ‘mean sea level’ surface, the geoid.If you
want to establish a 3D reference surface for a particular area (state, country, and continent)
you haveto adjust the ellipsoid for these discrepancies so that the reference surface closely fits
the actual surfaceof the Earth.A datum is an ellipsoid that is adjusted so that it matches the
actual shape of the Earth of aparticular region as well as possible. The datum serves as the 3D
reference surface for calculating thegeographic coordinates of a location.If you define a
projection, you can choose between two coordinate systems:
Geographic coordinate system
Spherical (3D) reference system. Locations described by latitude and longitude. Map
units:angular (decimal degrees).
Projected coordinate system
Planar (2D) reference system. Locations described by an X and Y coordinate. Map
units:linear (meters, miles etc.).
From a 3D reference surface to a 2D map projection plane
By using a set of mathematical functions, the geographic coordinate system of a spherical
(3D) reference surface (the datum) can be transformed or projected, to a projected coordinate
system of a (2D) projection plane. The outcome of this transformation is a map projection,
which can be definedas a systematic arrangement of parallels and meridians on a plane
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surface. Projectedcoordinate systems describe locations by Cartesian (X, Y) coordinates and
linear map units.Map projections allow areas on the surface of the earth (spherical surface) to
be represented on a map(flat surface).
However, expressing a three-dimensional surface in two dimensions involves distortion
ofgeometric properties shape, area, distance, and direction. As a map maker, you must choose
a map projection according to the properties you want topreserve in your map. This clearly
depends on the purpose of your map.
Adjusting Data frame Coordinate System
When you add a new data frame to an Arc Map document, the coordinate system of the data
frame is notyet defined. The data frame takes automatically the coordinate system of the first
dataset added tothe data frame. If you choose to add more datasets after the first, then these
datasets are displayed as ifthey have the same coordinate system as the data frame. For
example, if the first dataset has the UTM projection, then all other datasets present in the
same data frame, are displayed as if they havethe UTM projection. Even if this dataset has
another map projection defined! This means thatdatasets that represent the same area with
different projections, still can overlap. However, when data sets that have the same coordinate
system are added to a data frame, the features in each layer are correctly positioned with
respect to each other. If you subsequently add a data set that has a different coordinate system,
ArcMap changes it to match the others in a process called “on-the-fly” projection. This new,
temporary projection is applied only within a particular data frame; the data set’s native
coordinate system (the one shown in its spatial metadata) does not change.
Defining and Projecting Coordinate Systems
Purpose
While working with GIS, it is very common to receive, or have access to data (maps) with
different projections, coordinate systems. In order to properly use these maps together in a
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GIS, some data inevitably has to be transformed to make it geometrically compatible to other
datasets. The aim with this exercise is to provide an introduction to map projections, to project
and reproject datasets in ArcMap.
DATA
In this tutorial you will find data already available in your working directory called
(D\MU_GIS\Spatial referencing\Map Projections\)
Defining a projection
You can use the Define Projection tool when your dataset does not have a projection defined.
Open the Layer properties of dataset ‘Tigray_tabias’. Click the source tab and confirm this
dataset does not have a projection.
Open ArcToolbox. Click Data Management ToolsProjections and
TransformationsDefine projections.
Click the Input Dataset or Feature Class dropdown arrow and select the
Tigray_tabias’ dataset.
Click the button next to the Coordinate system box. The Spatial Reference Properties
window opens. Click Select. You can choose between geographic and projected
coordinate systems.
Browse to the coordinate system you want to assign to the dataset. Click Add.
Click Apply and OK. The Spatial Reference Properties window closes.
Click OK to run the tool.
Project this dataset use projection file:-Projected coordinate systems \ UTM \ Africa\.
Adindan_UTM_Zone_37N
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Re-projecting spatial datasets
When you collect datasets from different sources to build a GIS application you will often end
up withdatasets that have different map projections. With the Project tool you can change the
map projection ofyour dataset.
INSTRUCTIONS:
1. Open Arc Toolbox Click Data Management ToolsProjections and
Transformations-FeatureProject
2. Select the Input Dataset or Feature Class you want to reproject.
3. Define name and location of the output dataset
4. Click the button next to the Output Coordinate system box. The Spatial Reference
Propertieswindow opens. Click Select. You can choose between geographic and projected
coordinates systems.
5. Browse to the coordinate system you want to assign to the dataset. Click Add.
6. Click Apply and OK. The Spatial Reference Properties window closes.
Change the map projection from ‘UTM’ to ‘Mercator’
-Give the new dataset the name ‘Tigray_tabias_mercator’, save the dataset in your
directory.
-Use projection file: Projected coordinate systems\ World \ Mercator (world).
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2. Geo-referencing
Introduction
The previous exercise was all about projection. It presented how a user can select the
appropriate coordinate system for the data in use. This part explains the procedure to passing
coordinates to a raster image (e.g.an aerial photograph, a satellite image or a scanned map) by
means of a number of control points, followed by the rectification of the raster image. When
you georeference your raster dataset, you define its location using map coordinates and assign
the coordinate system of the data frame. Georeferencing raster data allows it to be viewed,
queried, and analyzed with other geographic data. Georeferencing will be made on: Satellite
images, Scanned maps and aerial photographs. After having the raster dataset, in order to
georeference an image, we should have sample ground control points of the features which
are depicted on the map. In other words, we should have to know the absolute location of
some representative features on the raster data set to be georeferenced. This is usually
achieved by using ground GPS collection if the image to be georeferenced is a satellite image
or aerial photographs. Scanned maps usually have absolute locations depicted with grids,
which could be used as GCPs in the georeferencing process.
In the coming two exercises, you will learn how to Georeference a Topomap Go to
C:\MU_GIS_GIS\Georeferencing folder and observe the JPJ image of Topomap of Mekelle
area. It is the scanned Topographic Map of the Surroundings of Mekelle Town. However,
since it is an image it is not a GIS data base, you cannot do any spatial analysis rather than
observing its attribute. Because it is an image, you cannot measure distances, calculate areas,
asses the connectivity of the roads etc. To do such spatial tasks, at first, the image must be
converted in to A GIS data base by Georeferencing it. So, in the following exercise we will
look at how to georeference the image.
Define a spatial Reference system for the source image
The first step of any GIS project is to select the appropriate coordinate system for our GIS
data set. As a result the first move of your project is to define the coordinate system of your
input image in to Adindan_UTM_Zone_37N. This is because; the Mekelle_map (your input
image) has been produced using a coordinate system of Adindan_UTM_Zone_37N. Then you
first will define the coordinate system of your input image as follows.
A. Create a new empty map
B. Add the Mekelle_map. jpg file from D:\MU_GIS\Georeferencing
C. When it warns as your data misses a coordinate system , press ok
D. Activate the Arc Toolbox window if it is not activated( go to Windows and click on
Arc tool box)
E. From the Arc Toolbox window, expand the Data management toolbox, and the
projection and transformation toolset.
F. double click on the define projection tool box
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G. In the incoming dialogue box, use the drop down arrow and select Mekelle_map as
the input data set
H. Click on the select coordinate system arrow
I. From the spatial reference properties dialogue box, click on the select tab
J. In the incoming browse for coordinate system dialogue box, double click projected
coordinate systemUTM Africa
K. Select the Adindan UTM Zone 37 N from the list of coordinate system under Africa
L. Click on Add in the browse for coordinate system dialogue box
M. Click ok on the Spatial reference properties and on the define projection dialogue
boxes.
The above step enables you to assign the appropriate spatial reference system for your image.
Following this, we will go to the actual Georeferencing procedure. In the Georeferencing
process, we will use the XY points written at the edge of the map and the respective grids as
Sample GCPS.
Geo-referencing on Scanned Topo_map:
As noted previously, the first requirement to Georeferencing images is to have control points.
So before proceeding in to the actual Georeferencing process, you must collect control points
from the input Topomap and record them. To do so, open the input topomap in the windows
explorer and record the coordinates of the four corners of the map by Zooming into them. The
table below shows the four corners coordinates of the given map. In the same way, try to
collect more control points from the given image.
A. Activate the Georeferencing tool bar (click on the top of the map document, around
the main menu and thick mark the Georeferencing tool bar.
B. Zoom in on the Top Left Corner of the image to the extent that you can see the X and
Y numbers written at the edge of the image(look on the screen shoot below)
C. Zoom in specific to the vertex represented by the X and Y points you have written (
you have to zoom in to the extent that you can identify the center of the vertex)
D. Click on the added control points icon from the Georeferencing tool box
E. Place the incoming cross at the center of the vertex you have zoomed in
F. Right click and press in put X and Y points
Easting(X) Northing (Y) Direction
550600 1492200 Left Top
551800 1492200 Right Top
551800 1491000 Right Bottom
550600 1491000 Left Bottom
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G. In the incoming small dialog box, enter the X and Y points that you have recorded
H. When you finish, press ok, then the image may disappear from the data frame
I. Click on the zoom to full extent button to repair the appearance of the image
J. Follow the above procedure and take 7 extra GCPs from the map document
K. First, take coordinates from the rest three corners of the map( Top right, top left and
bottom left corners of the map which was not taken before) It is advisable to take the
first four coordinates from the corner of the map so as to make the distribution of
sample GCPs fair
L. Try to take 4extra fairly distribute GCPs from other vertexes of the grids
M. You can take GCPs from any grid junctions. But your GCPs must be fairly distribute
through the map
Checking Accuracy
A. See the attributes of your sample GCPs by clicking on the View link table in the
georeferencing tool
B. Check the total RMS accuracy is less than 1 on the link table dialogue box
C. If it is the total accuracy is greater than 1 m you should have to redo the
georeferencing process.
Rectification of the raster image (geocoding)
This process is required if you like to reorient or resize the image towards the map coordinate
system of the control points. A rectified image, with a new position and a new value for each
pixel is generated. Rectification in a very simplified sense is the process of saving the
georefernced image. It will attach permanently the absolute location of every pixel on the
georefernced image.
A. Click ‘Georeferencing’ tool Rectify
B. In the rectify dialog box, click on the browse folder icon
C. In the select workspace dialog box, proceed to D:\MU_GIS\Georeferencing folder
D. From the list of folders under MU_GIS folder, select Georeferencing
E. Click on the Add button
F. In the Save As Dialog box, edit the output filename to be Mekelle_rectified_map
G. Using the drop down arrow in front of the format option, select TIFF
H. Click Save when you finish
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Exploring the Properties of the Geo-referenced Image
The following practice will help you to better understand how Georeferencing is a necessary
condition of any GIS project
A. Close the existing Arc map and open a new empty map
B. Add the layer Quick Bird.img, Image from D:\MU_GIS\Georeferencing
C. This is a georefernced satellite image of Mekelle City, Kedamy Woyene area
D. Add the rectified base map of Mekelle_City
E. In the map window, you have seen the satellite image overlaid by Rectified topomap
.img layer
The browse folder
icon
Edit the filename
Select the output format
Proceed
C:\GeES_GIS to
Select the
4. Georeferencing folder
Click on the Add
button when you
finish
Click on Save when you finish
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Zoom in to a road and you can check how the road position in the two images (rectified and
quick Bird image of Mekelle city) overlaps
Independent Exercise
Find the base map of Hawelti Sub-city and satellite image of the same area from
D:\MU_GIS\Georeferencing folder and Geo-reference it with RMS error of less than 1M.
Save your output file in TIFF format inside the same folder using Hawelti_subcity_rectified
as a file name.
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3. Geodatabase Management
A geo database is a spatial database designed to store, query, and manipulate geographic
information in ArcGIS. A geodatabase contains three primary dataset types:
Feature classes
Raster datasets
Tables
All three primary datasets in a geodatabase (feature classes, raster datasets, and attribute
tables), are stored using tables. Tables provide the primary storage mechanism for
geographic datasets. Geodatabase is designed to use the strong capabilities of querying and
set processing of rows in tables using SQL.
Tables contain rows.
All rows in a table have the same columns.
Each column has a data type, such as integer, decimal number, character, etc.
A series of relational functions and operators (such as SQL) is available to operate on
the tables and their data elements.
The spatial representations in geographic datasets are stored as either vector features or
rasters.
Feature classes: are collections of common features, each having the same spatial
representation, (such as points, lines, or
polygons), and a common set of attribute
columns, for example, a line feature class for
representing roads. The most commonly
used feature classes in the geodatabase are
points, lines, and polygons.
In the geodatabase, each feature class is
managed in a single table. A Shape column
in each row is used to hold the geometry or
shape of each feature.
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Raster datasets: represent geographic features by dividing the world into discrete square or
rectangular cells laid out in a grid. Therefore, a raster is a set of cells arranged in rows and
columns. Each cell has a value that is used to represent some characteristic of that specific
location, such as temperature or elevation. Raster data is typically much larger in size than
features and requires a side table for storage.
Therefore, we can visualize a geodatabase as a "container" used to hold a collection of
datasets. Geodatabases can be used to organize feature classes (such as points, lines and
polygons), raster datasets and attribute data which represent geographic objects in the real
world. In a single geodatabase you can organize polygon feature classes representing zones
and woredas, a line feature representing roads, a point feature class representing schools, and
a raster dataset that depict the elevation of your region.
Geodatabase can be:
PersonalGeodatabases - All datasets are stored within a Microsoft Access data file,
which is limited in size to 2 GB.
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File Geodatabases - Stored as folders in a file system. Each dataset is held as a file
that can scale up to 1 TB in size. The file geodatabase is recommended over personal
Geodatabases.
Purpose
The aim of the exercise is to deepen your knowledge on Geodatabase management. To this
end, trainees will learn how to create and manage a geodatabase using ArcCatalog and
bringing field data into the ArcGIS software program.
Data
The dataset that is going to be used with this exercise is found in your working directory
already saved as D:\MU_GIS\Data Entry\Geodatabase Management
How to create and manage a geodatabase by using ArcCatalog.
Creating a new file geodatabase
Start Arc Catalog.
Under the Catalog Tree, right-click on the location where you want to create the new File
Geodatabase; go to “D:\MU_GIS\Data Entry\Geodatabase Management”
” folder to create a new geodatabase as indicated in the figure below.
Point to new, and then click on File Geodatabase.
Arc Catalog creates a new geodatabase in “D:\MU_GIS\Data Entry\Geodatabase
Management”. You now have a geodatabase named “New File Geodatabase”.
To give the newly created geodatabase a more descriptive name, click on New File
Geodatabase and type “Services_and_Facilities”.
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Press Enter.
Now you created a geodatabase called “Services_and_Facilities”. However, your geodatabase
is empty; it does not contain any datasets. So you need to add all your datasets representing
the services and facilities in “Services_and_Facilities” geodatabase.
Adding data into your geodatabase
Now that you have created a geodatabase, you need to move your data into
“Services_and_Facilities”. To do so:
Right-click on “Services_and_Faciblities” geodatabase you just created. Go to Import, then
Feature Class (Multiple)... as shown below.
Feature Class to Geodatabase (multiple) window will appear. This tool is used to specify
your input and output features as well as the geodatabase to which you intend to add datasets.
Because you opened this tool by right-clicking on “Services_and_Facilities” geodatabase the
Output Geodatabase is already filled in for you.
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Under Input Features, click on the folder icon beside the empty rectangular box.
Navigate to your “D:\MU_GIS\Data Entry\GeodatabaseManagement folder and from
the folder that refers to select “Roads.shp”, “Health.shp”, “Religious_Facilities.shp”,
“MainRivers.shp” and Water_Facilities.shp”.
When you are done, click on Add button. It would take some time to add your data to
your “Services_and_Facilities” geodatabase.
Finally click on OK button.
Now you successfully add five dataset (i.e “Roads.shp”, “Health.shp”,
Religious_Facilities.shp”, “MainRivers.shp” and “Water_Facilities.shp”) geodatabase.
Under the Catalog Tree, click on “Services_and_Facilities”geodatabase. Then click on
Contents tab, the five features you added to your geodatabase should be displayed as shown
in the figure below.
The files you need to add to your geodatabase may include not only feature classes but also
tables. To add tables to your geodatabase follow the following steps.
Right-click on “Services_and_Facilities” geodatabase; go to Import and then click on
Table (single)… as indicated in the figure below.
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A Table to Table window will pop up which enables you to import tables to you
geodatabase. Click on the folder under Input Rows to choose a table you want to import
to “Services_and_Facilities”. For this exercise navigate to your “D:\MU_GIS\Data
Entry\Geodatabase Management” folder and select “GPS_data”.
The fields of the table you choose to import to your geodatabase would automatically be
displayed under Field Map (optional).
Under Output Table write the name of your table GPS_data.
To complete the importing process, click the OK button
Creating files for further digitizing different feature classes.
Following the creation of File Geo-data base, different files for different feature classes are
created in order to facilitate creation of new feature class by digitizing.
Data: D:\MU_GIS\Data Entry\Geodatabase Management
Open arc catalog and navigate to D:\MU_GIS\Data Entry\Geodatabase
Management \ Services_and_Facilities.
Right click on the Services_and_Facilities file geo data base → New → Feature class
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On the new feature class pop up window, write Banks_Mekelle under name and select
point feature under type → Next.
On the next pop up window select projected coordinate system then select Adindan
UTM zone 37N as indicated below. Then next → Next →Next→Finish.
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To create line and polygon features, the steps are similar and the differences are:
On step 3, write Roads_mekelle for the name and select line feature for type.
Write Business_blocks for the name and select polygon features for the type in case of
polygon.
Updating attribute table
For this exercise navigate to your “D:\MU_GIS\Data Entry\Geodatabase Management\”
folder and select “Schools.shp”. Open the attribute table of “Schools” and you will see that
some records (i.e. schools) have no value in “SC_NAME” field. Next, we will see how to
update an attribute table.
You can either edit one record at a time or many records at a time.
To edit record of an attribute table one by one:
Open the attribute table of “Schools”.
From the Tools bar, click on EditorStart editing.
A Start Editor window will pop up, select “Schools”.
In the first record that has no value under SC_NAME field, click on the cell and write
“School A”.
Go to the Tools bar and click on EditorSave Edits. Once more click on
EditorStop Editing.
NOTE: In order to permanently change the value of a field you have to save your edits.
To edit a number of records at a time:
Select some records from HawzenWoreda. The records will be highlighted in green as
indicated in the figure below. Assume these are “NEW” schools built recently.
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Right-click on Remark field and go to Field Calculator … as indicated below.
A Field Calculator dialog box will pop up. In the blank box under “Remark =“write
“NEW” (with a quotation mark) and click OK as shown in the figure below.
The quotation marks are necessary because Remark field has a String field type. The
quotation marks will let ArcGIS recognize what you write (i.e. NEW) as string. If you do not
write NEW in quotation, you will get an error message.
What you just did was, for the schools that you assume are built recently, you assign “NEW”
as a value for Remark field. In doing so you were able to edit the data of many records at a
time.
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Digitizing
Digitizing is the process of using a mouse to automatically store locations of geographic
features by converting their map positions to series of x, y coordinates in computer files or
database with an associated table. If your data consists of features too small to be depicted
either as lines or areas, then you should create an ArcMap Point dataset. Points represent
discrete locations such as houses, school, and health facilities etc.
Manual Digitizing
Digitizing is the process of interpreting and converting paper map or image data to vector
digital data. In manual digitizing you trace the lines or points from the source media. You
control a cursor, usually with a mouse or digitizing puck, and sample vertices to define the
point, line, or polygonal features you wish to capture. The source media may be hardcopy,
e.g., maps taped to a digitizing table, or softcopy, e.g., a digital image or scanned map. ESRI
software allows us to digitize using either hardcopy or softcopy sources.
On Screen Digitizing in ArcMap
Our practice exercise will involve digitizing a set of features from a scanned photo. Digitizing
directly on screen is sometimes called “heads-up” or softcopy digitizing. Flatbed scanners and
digital cameras are common, so softcopy digitizing is a standard procedure. Scanned photos
have some geometric distortion that depends primarily on how the photo was taken (flying
height, terrain, camera tilt, and other factors). GIS data are commonly entered from scanned
photos because we can easily adjust the display scale, zooming in or out as needed. This often
reduces both interpretation and digitizing errors.
Setting File Properties
Digitizing changes the contents of files, so you must have permissions to modify old files, or
to create new files in a workspace. Data on the hard drive may be write protected, so that they
may not be edited. The computer administrator may have denied access to certain data, or
only allow read access, to protect these data from inadvertent modification. This protection
sometimes becomes a problem if you wish to edit data, because you need to write data when
editing. You might think you can avoid this problem by copying the data to a portable drive.
Purpose
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In this exercise you will be introduced to basic digitizing techniques using ArcMap. Besides,
adding attribute to digitized features and calculating the area of polygons and length of line
features.
Data
The dataset that is going to be used for this exercise is found in your working directory
already saved as D:\MU_GIS\Data Entry\Geodatabase Management\services and Facilities
Open a new ArcMap file add the working data in this case “Banks_mekelle” and
“Mu_ikonos_utm_img” from D:\MU_GIS\Data Entry\Geodatabase Management\
Services and Facilities.
Go to editor and start editing → select Banks_Mekelle .
From the ikonos image identify location of some of the banks in Mekelle and left click
on those lacations one by one.
After you finish the banks go to editor→ save edits →stop editing.
Remove the Banks_Mekelle layer and add Roads_Mekelle from the same location in
the directory.
Go to the editor and start editing
Select Roads_Mekelle
Digitize some of the roads by single left clicking at every junction and double click at
the end of each road.
Continue with the other roads and the end go to editor and save edits and stop
editiong.
Remove Roads_ Mekelle and add Business_Blocks from the same directory.
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Go to editor and select Business_Blocks.
Digitize some business areas in the city by single clicking at every corner and double
clicking at the end of each polygon.
Go to editor save edits → editor→ stop editing.
Adding attributes to polygon features
In the previous exercise you digitized business blocks of Mekellecity. No tabular data
(attribute data) describing certain characteristics of these polygons have been added yet.
When you create a new vector dataset in ArcMap, an attribute table is automatically created
for this dataset. For each digitized polygon a record is automatically added to the attribute
table.
Initially the attribute table will contain three fields, called FID, ID and Shape. The FID field
contains unique identifiers of the features in the vector dataset. The unique identifier links the
thematic (attribute) data to the geometry of a geographic feature. These unique identifiers
cannot be changed. In the ID field a user-defined identifier can be stored. The Shape field
stores the feature type of the geographic feature (points, lines or polygons).
Calculating the area of polygon features
In ArcMap you can calculate the area of the polygon features of a dataset. First of all you
have to add an extra field to the dataset. After adding an extra field to the dataset it’s possible
to calculate the areas of all polygon features.
Open the Attribute Table of the Business_Block you digitized.
Click on the table Options button in the left top corner of the attribute table and choose
Add field.
Add a field to the attribute table of this dataset. Name the field Area (data type =
double, precision = 10, scale = 2). And click Ok.
A new field with name “Area” is added into the attribute table.
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Type of field: According to what data you want to put in the added field: Short Integers or
Long Integers, when you add numbers without decimals. Float or Double, when you add
numbers with decimals. Text, when you want to add text. Date, when you want to add a date.
Right-click the field heading for this new area field and click Calculate Geometry.
The Calculate Geometery dialog box opens.
Check the unit and click Ok.
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4. Spatial Analysis with Vector data
Selecting features by using a query expression
A query expression is a precise definition of what you want to select. Building a query
expression is apowerful way to select features because an expression can include multiple
attributes and operators.The expression contains logical operators: Boolean (AND, OR etc.)
and relational (=, <, >, <> etc.). Theoutput of the query expression is therefore TRUE or
FALSE. The features for which the querycondition is TRUE are selected; the features for
which the condition is FALSE are not selected. When you select features, they are
highlighted. Features remain highlighted until you make a differentselection, or when you
deselect them. When you open the attribute table, the table records for the features you
selected are also highlighted.
Purpose
The aim of this exercise is to describe the difference between tabular dataset and spatial
dataset queries. Queries are processes that extract information from a GIS by making
selections from tabular and spatial datasets.
Data
The dataset that is going to be used with this exercise is found in your working directory
already saved as (D:\MU_GIS\Spatial Analysis \Queries\).
Open the attribute table of the dataset you want to query.
Go to Options Select by Attributes you can also click Selection in the Menu bar and
click Select by Attributes.
The Select by Attributes window Appears.
In the Method field the selection type can be defined.
Double click the attribute to define on which attribute the selection is based. This
attribute appears in the text field.
Specify the condition in this text field by using the operators (=, >, <, etc.).
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Type a value into the expression, or Click on the Get Unique Values to retrieve all
values of the selected attribute.
Now you have built a single query. To Build a compound query you have to use the
‘And’ or ‘Or’ operators. If you want to build a compound query, use the ‘And’
operator when both expressions must be true. Use the ‘Or’ operator when at Least one
expression must be true.
Click Apply to make the selection.
Click the Clear Selection button to clear the selection. This button is available in the
attribute table under the button Options.
To find out how many features fulfill the conditions in your expression, or to review the
attributes of the selected features open the attribute table. The number of records that are
selected is displayed at the bottom of the attribute table!!
Select features from dataset ‘Main River’ that have a length of more than 4000meter.
a. How many features are selected?
b. Write the query of exercise down according to the formal structure of a SQL query.
Select
From
Where
Sorting attributes
By sorting an attribute table you can list the features in order of importance.
In the table, right-click the header of the field you wish to sort the attribute values for.
Select the Sort Ascending button to sort the attribute values, smallest values first or in
alphabetical order.
Select the Sort Descending button to sort the attribute values, highest values first or in
opposed alphabetical order.
Feature selection by spatial relationship
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The Select by Location functionality can be used to select features (target features) that are
within aspecified distance to user-defined source features in the same or a different dataset.
When you use the Select by Location functionality, select first the source features with a
tabular data query before youstart to use the tool.
Select the source feature(s).
Click in the menu bar: Selection Select by Location.
In the window that appears certain choices have to be made. For instance, you want to
select the Cities feature that is intersect to Main river feature. First select the Cities
feature of your interest. Then open the Select by Location tool.
Make sure the ‘Use selected features’ is checked.
Click Apply.
Select the features from the dataset ‘Main river’ that are within 4000 meters from the Cities
feature withCities name, "Z_NameF" = 'Mekele Especial Zone'. How many features of the
Main river dataset are selected?
Saving your selection into a new vector dataset
You have seen that there are many possibilities to make a selection. In many applications you
might want to use this set of selected data for further analysis. So it can be convenient to store
this set of data as a new dataset (shapefile). Note that by doing this, there is no change in
geometry and attribute information.
a. Select 'Mekelle Especial Zone’ from the dataset Woreda.
b. Export the selected features to a new dataset.
Select features of your interest.
Right-click the dataset with the selected features and click Data Export Data.
A dialog box appears. Click the Export dropdown arrow and choose if you want to
export the selected features or the complete dataset.
Specify the name and output location (workspace) of the new dataset.
Click OK.
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Append
Appends multiple input dataset into an already existing target dataset. Input datasets can be
point, line or polygon feature classes, tables and raster data sets.
Open a new, blank map by clicking on the “New Map” button in the upper left
corner of your screen below the “File” button.From your (C:\MU_GIS\Spatial
Analysis\Append\) folder, add the “Enderta” and “Mekelle” shapefiles
In Arc Toolbox select: Data Management ToolsGeneralAppend
Choose the input Datasets; define the name and location of the output dataset.
Click OK
Append ‘Enderta’ and ‘Mekelle’ data set.
Topological overlays
With topological overlays you integrate geometry and attribute data spatial datasets. In this
way you create new spatial data that gives you new information. ArcGIS offers a variety of
overlay tools (the Analysis toolset in Arc Toolbox). There are different types of vector
overlays: Intersect, union, Erase and clip etc.
Intersect
The Intersect function computes a geometric intersection of the input features and a tabular
join of theattribute tables. Features or portions of features which overlap in all dataset layers
will be written to theoutput dataset.
Union
Union is a topological overlay of two or more polygon spatial datasets that preserves the
features thatfall within the spatial extent of either input dataset; that is, all features from both
datasets are retainedand extracted into a new polygon dataset and a tabular join of the attribute
tables is computed
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Erase
Erase creates a new feature class by overlaying two sets of features. The Erase Features
polygons define the erasing area. Input Features or portions of input features that overlap the
Erase Features are not written to the output feature class. Input Features can be points, lines,
or polygons, but Erase Features must be polygons.
INSTRUCTIONS:
1. Display the datasets you want to intersect.
2. Select the features you want to intersect. If no features are selected, all features will be
used in the intersection.
3. In Arc Toolbox select: Analysis ToolsOverlay Intersect. A dialog box opens
Choose the input features; define the name and location of the output dataset.
4. Click OK (leave the other options on default).
Intersect dataset from (D:\MU_GIS\ Spatial Analysis\ Intersect) Intersect‘Mekelle’ with
Soil type. Save the output dataset in your workspace.
a. How many polygons features does the output dataset contain?
b. Recalculate the area of the features of the intersect output dataset. What is the total area
of the output dataset?
Clip
The clip operation uses one input layer to change the feature geometry of a second layer. This
process works like a cookie cutter and creates a new layer by clipping the first layer, called
the input layer, with a clip layer so that features from the input layer that fall.
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INSTRUCTIONS:
1. Select the features which define your clip feature
2. Open ArcToolbox, click Analysis Tools>Extract>Clip
3. In the next dialog screen select your input
4. Select your clip features
5. In the box “output feature class” you can specify the name and location of the
output.
6. Press OK
From (D:\MU_GIS\ Spatial Analysis\Clip) Add Road and Mekelle datasets Clip the road of
Mekelle from the Road dataset.
Reclassification
1. Open a new, blank map by clicking on the “New Map” button in the upper left
corner of your screen below the “File” button.
2. From your (D:\MU_GIS\Spatial Analysis\Reclassification\) folder, add the “health”,
“Roads” and “Woreda” shapefiles. Double click on your “Woreda” layer in order to
open up the “Layer Properties” window. And choose the “Symbology” tab.
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3. Click on the “Graduated Colors” under the Quantities option on the left side of the
Layer Properties window.
4. Choose TOT_POP in the Value Field, which is the population count
per woreda in 2007.
5. Classify your data accordingly by clicking on the “Classify” button and
choosing classifications for your values (Click on the arrow to the right
of “Classes” and choose 6. Click on the arrow to the right of “Method” and choose
“Manual”).
6. Change all of your labels following the graphic above. Then click out of the labels box
and press Apply and OK to return to the mapping screen.When finished, press Apply
and Okay.
7. Make sure that your “Roads” layer is on and that you have classified your roads in
hierarchical order.
8. It is interesting to note spatially how population follows critical road infrastructure and
service and facilities too. But, is population counts an appropriate measure to
understand relationships between infrastructure/service and facilities and
demography? Let’s experiment with a different measurement to understand the
differences and then create a map of both.
9. Right click on the “Woreda” shapefile name in the table of contents and press copy.
10. Scroll to the top of the Table of contents and right click on Layers tab
and choose “Paste Layers”. This will copy the same layer that you have already built
on population count into the Table of Contents.
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You will now have two of the
same “Woreda” layers in your
table of contents.
11. Now, double click on
the new “Woreda”
layer that you just
copied into your table
of contents and Click
on the “Graduated
Colors” under the
Quantities option on
the left side of the
Layer Properties window (as you did before in step 5 above).
12. Choose Pop_Dens (this is the population density: average people per square kilometer
by woreda).
13. Classify your population density data by clicking on the “Classify” button
andchoosing classifications for your values. See the picture to the right under the label
“Range” which shows how we classified our data. (Look at step 5 above if you need
help). When finished, press Apply and Okay.
14. Left click on the Symbol tab above the color squares and choose Properties for all
Symbols. Under the Outline Color tab, choose No Color for your outline color and
then press OK until you exit Layer Properties.
15. Notice how population density changes the further away one gets from the main
infrastructure corridors. Turn off and on the “Roads” layer in order to see the Density
differences under the “Roads” corridors.
16. Now add your “Regions” shapefile. Left click on the colored square underneath the
layer in the table of contents in order to open the Symbol Selector window. Choose the
“Hollow” option and press okay.
17. Turn off the “Roads” layer and just look at the differences between Population Density
and Population Count. You can do this by turning off and on the Population Density
“Woreda” layer. The layer beneath it is the Population Count layer.
18. Looking at the Population Density map, we can see that parts of REGION have very
high population density (see two maps below). In these high population density areas,
what does the road infrastructure look like? Are they well connected?
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Buffering
The Buffer tool is used to identify or define an area within a specified distance around a
feature. For example, you may create a buffer to define an area around a river to identify land
that should not be developed, or, you may want to
create a buffer to select features within a specified
distance of a feature (Rural Access Indicator – 2 km
from a road).
In this section we will create exclusion zones around
the main rivers in the region. Suppose a Regional
bureau wants to evaluate areas where natural water
areas should be cleaned to preserve freshwater and
increase water flow and would like to know how
many cities are within 5 km of a stream or river, and what the total population of these cities
is in order to analyze affected population and model economic impact.
Open a new ArcMap session. Click on the new map icon .
From (D:\MU_GIS\Spatial Analysis\Buffering\” folder, add the “Regions”, “Cities”
and “MainRivers” shapefiles.
Since you are starting a new Exercise, save your mapfile
as: Buff_YOURNAME.mxd
Activate ArcToolbox by clicking on the toolbox icon.
Choose Analysis Tools Proximity Buffer.
Populate your buffer wizard following the example to
the right, making sure to save your output to your
“Buffering” folder.
Click OK.
The output should automatically add to the
data frame.
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Now that you have determined the 5 km buffer zone.
If you display your “Rivers” layer on top of
the buffer layer and you zoom to a specific
area, you will see how the buffer has created a
5 kilometer area around the river (see right).
Now you will now isolate the communities
that lie within this 5 km of this buffer zone.
From the main menu click on the “Selection”
dropdown menu, and choose the “Select by
Location” option.
Select features from “Cities” that intersect
“MainRivers_buffer”
Click OK.
The appropriate cities should now be highlighted in your map.
To export these as a separate file, right click on the “Cities” layer, scroll to “Data” >
“Export Data”, and save to your “Buffering” folder as “Cities_5km”
Now turn off all layers except the “Regions”, MainRiver_buffer”, and “Cities_5km”.
Summarizing a field
You can get more statistical information for all records in a table or just selected records by
using the Summarize option. Summarize creates a separate table that contains the statistics for
a field by unique value or category.
First let’s see how much
population per Region will be affected.
Open your “Cities_5km” attribute table.
Right click on the column title “Z_NameF”
and click on “Summarize”. Fill out the
summarize window as you see to the right.
Save your table to your “Buffering” folder as
pop_sum. When finished, click OK.
Now right click on your table that you added
to your screen and open the attribute table
and look at the various columns that were
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created.
The Count_Z_NameF column tells you how many cities/Cities per zone are within 5
km of a river. The remaining 4 columns gives you the minimum, maximum, average,
and sum of populations in the cities that are within 5 km of a major river by Zone. (see
below)
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Section V: GPS data collection and Management
Introduction:
A Global Positioning System (GPS) device allows you to quickly find your position within
several meters. It is a satellite-based navigation system that sends and receives radio signals.
A GPS receiver acquires these signals and provides you with information. There are different
types of GPS devices. For this training, we will use the Garmin eTrex Vista GPS.
By the end of this exercise, you should be able to:
1. Be familiarized with Garmin eTrex Vista GPS;
2. Collect point data using GPS
3. Import the collected data in to ArcGIS:
(i) Manually, and
(ii) Automatically using DNR Garmin software
4. Convert the point data in to shape file
The Garmin eTrex Vista GPS
Major buttons of the Garmin eTrex Vista GPS
Figure 1. The major buttons of a Garmin eTrex Vista GPS
• POWER button allows you to turn the unit on or off.
• PAGE button allows you to move through the four different GPS screens
• UP/DOWN allows you to move through menus, increase or decrease settings, flip through
options
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• ENTER allows you to select an option or open a menu
• To Turn the GPS Unit On/Off:
• Press the POWER button. (Please do not forget to turn the unit off whenever it is not in
use as the batteries run down quickly)
• You will get a message, “Wait…tracking satellites”(A good signal needs 4 satellites—
takes up to 5minutes)
• Getting a good signal:
-Moving around, especially in a straight line, helps the satellites locate you faster
-If you are under a dense canopy, it helps to track satellites in a nearby open area
first, then bring unit (with the power still on) back to the plant population
• Accuracy: GPS unit will show accuracy at the top of the screen when you first turn on the
unit. Try to get about 8m accuracy in open areas (if the error is a very large number at
first, keep the unit on and wait a few minutes for the error to reduce as you walk around)
To Check/Adjust Settings before Taking a Reading (crucial before recording
coordinates):
The first time each GPS unit is used, the data formats may need to be changed to conform
with the required standards and interest of the researcher.
• Press the Page button on the right side of the unit until you reach the Menu page, and
• Scroll down to Setup using the Up/Down Buttons.
• Scroll down to Units and change them using the Up/Down Buttons to scroll and Enter
to select.
• There are six settings: “Position format,” “Map Datum,” “Units,”, “Distance/speed”,
“Elevation”, “Depth” and “Pressure”.
• Select “POSITION Format,” and using the UP/DOWN buttons highlight “UTM
UPS,”
• Press ENTER to select this option
• Select “MAP DATUM”, and using the UP/DOWN buttons highlight “WGS 1984”
press ENTER
• Select “DISTANCE,” and using the UP/DOWN buttons highlight “METRIC,” press
ENTER
• Select “ELEVATION,” and using the UP/DOWN buttons highlight “METERS,”
press ENTER.
• Select “DEPTH”, “METERS”
• Select “PRESSURE”, “MILLIBARS”
COLLECTING POINT DATA USING GARMIN ETREX
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The following is a step-by-step guide to collecting points using the Garmin Etrex.
(i) Finding a Suitable Location
You should find a suitable location in collecting data using GPS. In urban areas, a street
corner or other open area is best, as far away from tall buildings as possible. Alternatively, a
reading can be taken from a rooftop.
In rural areas, the location should be in a clearing, outside of the tree canopy, as far away
from buildings or mountains as reasonably possible.
(ii) Marking the Location and Naming the Waypoint
• Press the Page button on the right side of the unit until you reach the Menu page.
• Use the Up/DownButtons to select Mark at the top of the screen and then press the
Enter button.
• Use the Up/Down Buttons to highlight the waypoint ID number in the flag.
• Press Enter. Note that the first digit of the waypoint ID is highlighted and ready to be
edited.
• Use the Up/Down Buttons to select the number you want, then press Enter.
• Repeat this process until you have renamed the waypoint.
(iii) Saving and Recording the data
The GPS reading should be saved in two places:
- on the GPS unit and
- on a paper form.
GPS units can be broken or lost, and experience has shown that a hardcopy backup is
essential. In addition, the paper form provides a backup should the data in the GPS unit be
changed, deleted, or misidentified (i.e., the operator names the waypoint incorrectly in the
unit). The paper form is also where notes should be made in cases where multiple points are
taken for one waypoint.
Each saved position is called a waypoint, and each waypoint has a unique name. When a
waypoint is saved, the receiver assigns it a default name. When the point is saved in the GPS
unit, the default name must be changed to the right name and ID number.
• Record the coordinates shown at the bottom of the GPS unit screen onto the paper
GPS waypoint Position Form.
Waypoint X Y Altitude Description
001 551504 1491895 2500 P1
002 551224 1491844 2501 P3
003 551001 1491704 2006 P4
004 550924 1491792 2008 P5
005 550901 1491737 2003 P6
006 551021 1491715 2007 P7
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Table 4.3.1 GPS waypoint Position form
•Record the coordinates into the GPS unit by using the Up/Down Buttons to highlight the
word OK, then pressing Enter. Your waypoint is now saved.
(IV)To check the waypoint location after it has been saved
• Press the Page button until you reach the Menu page.
• Use the Up/Down Buttons to highlight the FIND option and press the Waypoints
option and press Enter.
• Use the Up/Down Buttons to select the waypoint for the point you are in and press
Enter to select.
(IV) To turn off the unit, press the Power button for several seconds.
Import the collected data in to ArcGIS
Importing manually
Record the GCPs points on Excel file and save it in D:/MU_GIS/ArcGIS and name it GCPs
● Add the Excel file in ArcMap
●Add the data in ArcMap
●Right Click on the layer (table)
●In the menu that comes click Display XY Data….
In the Display XY Data window click Edit
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●In the Spatial Reference Properties window, select the coordinate system appropriate for the
data. Edit > select > Projected coordinate system > UTM > WGS 1984 >WGS 1984
UTM Zone 37N. Prj> add > apply > ok> ok> ok.
●The point spatial data (your GPS data) will be displayed in the map window of ArcMap.
● In order to save the data permanently, right click on the layer added during the previous
process. In the menu that appears click Data > Export Data
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In the export data window browse to the location where you want to save the shapefile and
name it “GCP.shp” In this case, D/MU_GIS/ArcGIS/GCPs.
●Ok
● Click “yes” to add the shape file as a layer
● Now, you can remove the other displayed layers and keep only the shape file.
● Done (now, your GCPs have been converted in to shape file format. Next time, you
can directly add the shape file using the add button.
Importing GPS data in to ArcGIS automatically
If the number of GPS data you have collected are very large, it may be time consuming and
tedious to enter the data manually in to a computer. In that case you should have to connect
the GPS in to a computer and load the data on it automatically. To do so, the first requirement
is to have the software for the GPS in which the data has been collected. Therefore, before
trying to load the GPS data in to a computer system, first you should have to have the
application software of the GPS you are using. Each of the different brands of GPS software
has their own application software. Thus the procedure employed to load GPS data in the
computer system will depends up on the type of GPS and the Brand that manufactures the
GPS. So the best way to practice loading GPS data in to a computer system is to read the User
manual of the GPS you are using.
In this training, we will use DNR Garmin software for importing the GPS data in to the
ArcGIS software.
Connecting the Garmin GPS unit to a computer
● Connect the GPS to the computer using the USB cable provided.
● On the back of the GPS there is an input for the USB cable in the lower left corner of the
unit; connect the smaller end of the cable here.
● the larger end of the USB cable must always be plugged into the uppermost USB port of
the computer itself (or if the CPU tower is on its side, the port furthest to the right).
● Turn on the GPSmap76CSx if you have not already done so. If a window does pop up
asking you to install network drivers say yes and complete the process.
● After you connect your GPS, browse the start menu and open DNR Garmin.
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Opening the DNR Garmin
● Double click the DNR Garmin icon on your desktop to launch the program.
● The software should automatically detect your GPS unit (GPS must be a Garmin
brand GPS). If it does not automatically detect your GPS, Select GPS from the
main menu bar, then select SET PORT, and then choose the appropriate port that
the GPS cable is plugged in to (USB if plugged in with USB cable).
• Once the software recognizes the GPS unit it should say Connected in the lower left
corner of the screen. The first time that the software is used, you will need to set up
some software parameters, beginning with the default Datum and Projection that the
software will use. Click on File, then click Set Projection.
• File > set projection > None (the red one) > WGS_1984_UTM_Zone_37N
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• Next we will configure default parameters for waypoints, tracks, routes, real-time
waypoints, ArcMap, and Units. Click on File, then click General Properties. Begin by
setting the Units parameters. Select Meters for measurement units. Select +3
(Baghdad) for time zone. Note: Ethiopia is found at +3 time zone.
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- Click on the ArcMap tab and review the settings.
- Click on the Route tab. Uncheck the fields which you do not need.
o OK.
o To download your GPS Data, click Waypoint > download (Note: if you have
collected track or route data, click the right button).
o Now all the GPS data you collected will be displayed in a tabular form
• File > Save to > File
• Select a File Name where you want to save your shape file
• Name the file “ GCP1”
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• Select “ArcView shapefile (projected) (*. Shp) from the popo down menu
• Save it in C/MU_MU_GIS/ArcGIS
• Now, you will be informed that “ File was written successfully to
D/MU_GIS/ARcGIS/GCP1
• Ok.
• Done. Now you have already converted your GPS data in to shape file.
Importing shape file to Arc Map
• Now the Add button in ArcMap to add the shape file “GCP1”
• The GCPs will be displayed now
• Done
Group Exercise
Instruction
At this stage, the trainees will be divided in to 4 groups of five members. Each group will get
a GPS and will collect GPS points and finally prepare the maps of different blocks in
Kedamay Weyane Sub City
Specific activities:
1. Five areas are selected and traines will be assigned to each of these selected areas.
Then, they will collectPoint Data, linear data and polygon data using GPS.
Note: Trainees should record the GPS reading in the following format.
Waypoint X Y Altitude Description
101 5554524 1378901 1801 St. Mary Church
102 5554599 1378976 1902 C1B1
103 5554351 1378965 1905 C2B1
104 5554565 1379000 1906 C3B1
105 5554598 1379701 1904 C4B1
106 5554577 1379705 1904 XX elementary school
107 5555487 1379888 1900 Mosque
108 5556783 1378965 1899 Node 1
109 5556799 1378999 1898 Node 2
etc
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2.Importing GPS data in to ArcGIS (both manually and automatically)
3. Making polygons (for buildings and blocks), line features (for roads) and point data
(schools, churchs, Mosques etc).
4. Overlaying the polygon, line and point features on Quick bird image of the the Kedamay
Weyane sub city
5. Preparing a lay out for the point, line and polygon features
Remarks
• Features like schools, churchs, mosques etc are represented by a single dot.
• For, linear featurs like roads and streams, trainees could collect two point data ( Eg.
Node1 and Node 2 in the table above; both at the beginning and end of the
roads/streams) and would convert them to linear features later in ArcGIS by
connecting the two point data.
• For polygons (Eg. Blocks of buildings) they could collect atleast four readings from
atleast four corners of the blocks but depends on the structure of the blocks.For
example, in the table above, C1B1 stands for corner1block 1, C2B2 stands for corner
2 Block 1 etc.
The study areas selected for this assignment are indicated in the following figure.