introduction to gis and preparing a base...

Introduction to GIS

Base Map Preparation Tutorial Part I

PLAN 211 Digital Visualization for Planning Fall 2006 Prof. David L. Phillips

Introduction to GIS Base Map Preparation Tutorial

PLAN 211 Digital Visualization for Planning 1

Introduction to GIS and preparing a Base Map Preface: A wealth of digital data exists for many jurisdictions. Charlottesville is typical of many small to mid-sized cities. Many of the legacy paper documents have been digitally updated. Others have been totally digitally generated. We will be using both to prepare a series of Base Maps for recording field observations on a neighborhood, recording pedestrian accessibility features, begin a photographic inventory and beginning planning graphics. To access this digital map data you will be using the ArcGIS software from ESRI that is available in the labs and studios throughout the University. Initially the software will be used for map construction and display. Later in the course we will do some analysis and digital visualization with the software. You will be producing documents that you will save digitally and printing for use in fieldwork. This document describes the products, the sources of data and the procedures for using the software to accomplish this project. Products:

A series of 8 x 11 printed maps of regular portions of the neighborhood in the vicinity of Gordon Avenue

A series of maps for use as underlays for field tracing.

These maps will show:

Air Photograph of the neighborhood Planimetric features: roads, sidewalks, other paved surfaces, buildings, tree groupings, Parcels of land ownership Reference Grids for aligning different layers of non-digital information.

Sources of Data: (all available in the Classes folder)

Orthographically corrected panchromatic digital air photographs of neighborhood. Planimetric features digitized from air photographs into CAD files. Parcel lines showing land ownership from tax assessment maps, surveys and recorded deeds

assembled by the City of Charlottesville. (2002) Procedure: Step- I. Acquiring Access to digital files with map data:

Establish a storage (not a workspace) on the Home2/Courses Home Directory Service. Log in to the Home Directory Service, but choose the Home2/Courses option from the drop down list

Note: Plan 211 students have already done this in the introductory session.



Navigate to the Plan/Plan211-Phillips folder and FILE>NewFolder and give it a name with your userid as the first characters. (e.g. abc6xStore) If you get an error message that you cannot create a folder, contact the instructor to check the permissions for your userid on this server.)

Navigate to the Home2/Courses/Plan/211_Phillips/DataforExercises directory and copy and

paste the GordonAveBase folder to the storage location you established above. Select the entire folder, right click, select PROPERTIES and uncheck the READ-ONLY permissions.

If asked whether to change the permissions on folders and files below this folder in the file

hierarchy, say YES. COPY the folder, then… Navigate to a working space on your workstation (T:/Temp for example) and Paste the

GordonAveBase folder and its contents in this workspace. Change its name to something like myGordonAveBase Our strategy is to work totally within this working folder and then backing it up in its entirety to the Home2/Courses server.

Normally planners would acquire data from their primary sources: the local government mapping department, regional, state or national agencies, contract for data, or use public services like Uva’s GEOSTAT center in the Library. Here we simply make it available to you.



STEP II. Identify the study are within the city. Digital Orthophotos and Planimetrics are arranged by the City of Charlottesville in a GRID with N/S and E/W numbering. The grid sections we will be using are N2W2 and N3W2 as shown below:

Step III: Working with Image elements in ArcMAP.

Start the application ArcMAP from the Start>Programs>GIS>ArcGIS menu sequence. A ArcMap dialog box will open on the screen suggesting that you begin with an EMPTY MAP. OK, the first time you work with information this is what you want. If you want to work with a

previously created map document, you would Browse for it in your workspace. Set up the page of the map using File>PageSetup>choose a B*W printer and LANDSCAPE

mode. To add the digital Orthophotos to your map, Use the ADD DATA command or BUTTON:



This produces a dialog box where you browse to find the orthophoto files. To aid in this, ArcMap

allows you to construct a direct path to your working directory. This is helpful:

Having browsed to your working space GordonAveBase and within that Orthos select one of the ortho.tiffs and click the ADD button to add it to your map:

If you are asked to Build Pyramids, respond positively as this will speed redraw time as you pan and zoom on the map.

Repeat this process for the two images in the study area. You may do this individually or as a

group using the usual SHIFT or CNTL key combination to make multiple selections from the Add Data dialog list.



Having added one image, the ArcMap window should look something like that below. The window has two major sections: The Table of Contents which lists the LAYERS in the map and the current MAP DATA FRAME on the right showing the content of the current map. [There is another way to view the map called Layout View which we will use later to “print the map”]

Also shown below is the Tool Bar for working on the Map. The usual zoom tools, pan tools and

“Full Extent” tools are the top six tools. Forward and Back allows you to move quickly to zoom extents already defined. The other tools are labeled below. You may want to try each of these out.

Select Identify Search Measure

[Digression] In the image on the next page shows two images are shown in the map. Notice that the mapping program aligns these images in their appropriate locations. Unlike a photo image program that simply treats the photos as images without spatial location, GIS places the images in known coordinate locations. While we did not pause to view the actual files in the ORTHOs folder, each image was in TIFF format (a raster methods of storing the image with little compression and no image quality loss). The image was accompanied by a .TFW file (called a TIFF World File) which contained information about the location of one corner of the image in real world coordinates, the size of each cell of the image raster and the rotation of the image if any. ArcMap reads the TFW and calculates where to place the image.



If you were to do this in a photo manipulation program you would have to create separate layers and then move and perhaps rotate the images into their exact location. This is time consuming and error prone.[End of Digression]

Maps have scale and projection

parameters that allow features on the round surface of the globe to be projected in coordinates on a flat surface (page or screen). You will now tell the ArcMap program what the parameters are for the data acquired from the city. Use the arrow cursor to select the

LAYERS label for the data frame as shown on the left. RIGHT mouse click to get the action menu and choose PROPERTIES.

This will yield a multi-tab dialog box where you will set the projection and units of measure:

First, in the GENERAL tab, set the Units of Measurement to FEET for both the Map and Display:



Second, in the Coordinate System tab, select the PROJECTED COORDINATE SYSTEM option

and browse down to find the STATE PLANE NAD 1983 (Feet) definitions and the Virginia SOUTH definitions.



The map window will now have a SCALE in the top status line and the coordinates in the bottom status line will be in true feet in the NAD 1983 State Plane Virginia South FIPS 4502 Feet coordinates.

If you have not already done so, SAVE your map. Use the FILE>MapProperties command to set the DATA SOURCE OPTIONS to RELATIVE PATH NAMES.



Then using the FILE>SAVE command. Place the map document in the same working folder GORDONAVEBASE (or what ever you named it) Here the tutorial has given it a name of BaseStart.mdx

STEP IV. ADDING FEATURES TO A MAP Add the neighborhood study boundary and sub-areas in the Geodatabase and add it to your

map: o Use the ADD Data button as before.

o Navigate to the Geodatabase o Drill down to find the Neighborhood and sub-area features within the Study Areas

Feature Data Set:

o o Zoom to the Neighborhhood by right clicking on the Neighborhood layer and selecting

“Zoom to Layer”.

o o Symbolize the Neighborhood as an outline only by clicking on the symbol below its name

and changing the fill color to “none” and select an outline color and thickness:

o



STEP V: Printing a map and Exporting Images Up to this point you have been creating a spatially related set of images in a “Data Frame”, but have not really produced a “MAP” that could be printed. These next operations will prepare the LAYOUT page for publication.

In the Table of Contents, create a “Photos” GROUP LAYER and place all of the images into this group. To do so, right click on the Data Frame “Layers” in the TOC and choose New Group Layer

Select and drag the different TIFFs under the Group. You will now be able to turn on and off all of

the layers in the Group at the same time.

Move from the Data Frame View to the Layout View by choosing the Layout button in the lower left corner of the major map window:

Your images should now appear inside of the Landscape oriented “page” you set up with Page Setup at the beginning of the exercise.:



Adjust the size of the Data Frame to fit the Page leaving some room at the top and bottom for other map elements. Do this by grabbing the handles on the frame and dragging to new position. Notice that the map does not become distorted if you move the frame by the side or top handles. The fact that the data is “projected” and not an image allows the software to maintain the proportions within the frame. (This is unlike resizing in pictures in Office, Powerpoint, Photoshop etc where you have to deliberately maintain proportionality by using the corner handles.)

In the Scale box of the Button Bar, set the scale to exactly 1:10,000:

Insert a Scale Bar onto your map document using the INSERT>SCALE BAR command.

A Scale Bar Selector dialog box allows you to choose the style of scale bar you wish to use and if you chose PROPERTIES, you will have access to modify the bar to your own style if necessary



(no need to do so on your first map.) Accepting your choices will result in the placement of the BAR somewhere on the LAYOUT. You will have to select and drag it to the location you wish:

Insert a North Arrow on the page using the INSERT>NORTH ARROW command. Make your

choices from the dialog box and place the arrow on the page. Insert a TITLE on the Map and a Text Box with you name and date. Editing the objects of text is

similar to most other windows applications. Double click on the object and work in the dialog box:



Notice that the data frame has a dark line around it. If you wanted to change this, choose the Frame, Right Click to get the menu for that object and choose PROPERTIES. You can then change the line thickness, color, shape, background color and any shadow drop you wanted to highlight your frame.

Save your working document being sure that the sources are saved as relative paths. (see above).

Print your map to a black and white printer. This should be a normal operation. You will

get some previews as you go. (The printer in the lab is 5si105)

Often you do not necessarily need a hard copy of your map. You may want to place your map in a powerpoint presentation or make it available on the internet. To do so FILE>EXPORT MAP command gives you the options of what types of digital image files you would want to preserve.

Useful to have an OUTPUT folder in your workspace.

EMF is good for Office Pictures (Power Point) PDF is good for printing and transmitting on JPEG is okay for small web images TIFF retains most detail for moving to photoshop but is big.



STEP VI: Adding Planimetric Data to your map. Planimetric data consists of a drawing of different observable physical features plus some references lines. Often these are generated from air photographs. Usually these are produced in CAD drawings with different features on different layers. As with the air photographs, a city cannot maintain only one planimetric drawing for the entire city, but divides the city up into “tiles”. We will examine one tile, but then work with data that has already been converted to GIS format.

Select one planimetric tile from the Planimetric Folder. (N2W2.dwg). Do not add the entire drawing itself, but drill down and choose the POLYLINE (not polygon) objects in the drawing.

Place this layer ABOVE the PHOTOS in the Table of contents. Notice how this draws the new layer ON TOP OF the image in the map.



Use the Zoom tool to locate the intersection of Rugby Road and Gordon Ave. Set the scale to 1:1,200.

Notice that the planimetric matches the photographs. Currently all of the lines are rendered the same color so it is not easy to determine what they represent. Next let us symbolize these lines by their CAD layers. Double click on the Drawing Layer or right click and choose PROPERTIES.

Choose the Drawing Layers TAB, DISABLE ALL and then reselect: Grid, Parking, Driveway, Roads, Structures and Vegetation.



You now have a cleaner Image and the features are more obvious on the planimetric. Return to the Layer Properties Dialog Box, Go to the SYMBOLOGY TAB and choose the

CATEGORIES Unique values option for symbolizing these lines:

Choose the LAYER as the Value Field and ADD ALL VALUES. Unclick the <all other values> so they will not be colored. Choose a Color Scheme.



This symbology box is where you might spend 50% of your time in making maps. This is how the cartographic quality of your maps are defined.

This map looks wild in color.

Turn off the Photo Layer:



Shift to the Layout Mode and observe your document:

You may want to specify the scale to 1:1200. Note how the scale bar made an automatic

adjustment. The scale bar is mathematically linked to the data in the data frame and the size of the paper. Insert a Legend onto the map using the INSERT>LEGEND command. You may want to right

click and change the PROPERTIES of the legend to give it a white background and may want to remove undisplayed layers from the legend. Print this map Export this map File SAVE your ArcMap document something like FirstPlan.mdx



STEP VII: SAVING YOUR WORK !!!! (BACKUP… BACKUP) You have already printed your map and have exported images of your map. You have also saved a file called FirstPlan.mdx or something like this. All of this saving should have been done in the workspace you created (BaseMap) on the temporary drive of the computer you are working on. You will now want to save all of this work to the servers for future use—potentially even on a different computer. Remember, right now all of the work you have been doing is on the local computer.

Be sure you have saved your ArcMap document with a File Save command. Be sure it is in the local workspace you have been using. Exit ArcMap Use Windows Explorer to COPY the entire WORKSPACE, not just the mdx document and

PASTE it back to your account on the server.( Home2/Courses/Plan/Plan211/ )… These files are large enough that you will not be able to save them to your regular home

directory. For safety, you may want to copy the FirstPlan.mdx file to your own home directory and perhaps the Output folder.

Again, copy and paste the ENTIRE WORKSPACE !! END OF EXERCISE 1 What is coming next? In preparation for our field work we will need to have much larger scale maps with selected details so we can make notes and use as trace backgrounds. We will define a study area and sub-neighborhoods. We will divide into six teams to examine the sub-neighborhoods.

introduction to gis and preparing a base...

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