gis orsop - home | umass amherst basics.pdf · the real world in this example, our landscape...

GIS Workshop Spring 2016Evonne Gong ([email protected])1/ 14

GISGeographic Information System. An integrated collection of computer software and data used to view and manage information about geographic places, analyze spatial relationships, and model spatial processes. A GIS provides a framework for gathering and organizing spatial data and related information so that it can be displayed and analyzed. In GIS, there are 2 basic spatial data types representing the real world, Vector & Raster.

IMPORTATNT!!!!!!• Use_an_underscore_instead_of_a_space as file names in ArcGIS.• Keep your data in one place!!! External hard drive, thumb drive.....ArcGIS references data files, it

doesn’t store them in your map (it treats the data files like an Xref in AutoCAD). If you move the reference data files or try to open your map on a different computer, all your links will be broken and no data will display. Package map, when sharing.

• Be organized!!! Each Shapefile is actually a collection of 5- 7 files with extensions like .dbf, .prj, .xml, and .sbn. GIS needs all of these files to be in the same location (file folder) in order to understand how to display the data. Don’t move them around or delete any by accident.

The Real WorldIn this example, our landscape consists of

• rolling hills• grassland• lake• rivers• forest stands• marsh

It can be represented as a series of raster layers and/or vector layers.

Raster DataIn the raster data model, land cover is represented as single square cells. Each cell will have a value corresponding to its land cover type. Raster data are good at:

• representing continuous data (e.g., slope, elevation, chemical concentrations)

• representing multiple feature types (e.g., points, lines, and polygons) as single feature types (cells)

• rapid computations (“map algebra”) in which raster layers are treated as elements in mathematical expressions

• analysis of multi-layer or multivariate data (e.g., satellite image processing and analysis)

• hogging disk space

Vector DataIn the vector data model, features on the earth are represented as

• points• lines / routes• polygons / regions• TINs (triangulated irregular networks)

Vector data are good at• accurately representing true shape and size• representing non-continuous data (e.g., rivers, political boundaries, road lines, mountain peaks)• creating aesthetically pleasing maps• conserving disk space


Where to find DATA - MassGIShttp://www.mass.gov/anf/research-and-tech/it-serv-and-support/application-serv/office-of-geographic-information-massgis/datalayers/layerlist.html

Open & SaveOpen ArcMap - New Map - Blank MapSave the map file to your drive

Add data

ArcGIS icon GIS map file icon

If you can’t find your data folder, click “ Connect to Folder“


1. Simple ChangeDouble click the symbol in the layers panel

2. Change symbol according to attribute field valuesRight click layer tile - Open attribute tableThis file is the .dbf file that forms the shapefile and can be opened in MS Excel. The MassGIS website contains the “metadata” that explains what each of these attributes means. Each feature (row) has an entry for each attribute (column). You can choose to display features by their attributes.

Edit Symbols & Labels


Double click on the layer title - layer properties - SymbologyYou can also change the layer opacity and labels in layer property.

Add Base Map


Pick a basemap

Go to Layout View

Right click on the paper - Page and print setup - Change paper sizeClick on the viewport to move it around or re-size it.Use the hand tool to move the map around within the data frame.

or

Map Layout


Add Map Elements• Add Data Frame (e.g. locater)• Title• Legend• North Arrow• Scale bar

Creating a dynamic locator mapRight click on the new data frame - Properties - Extent Incicators


Exporting / Sharing


• INPUT FEATURE is the layer you would like to buffer (usually streams or wetlands, sometimes roads or other features). Choose from the drop down menu of layers in your map or browse folders using the folder icon.

• OUTPUT FEATURE is the new shapefile that will be created. The default is to save the new file in the same folder. You should use the folder icon to navigate to your drive and rename/save the file accordingly.

• Enter the DISTANCE you would like to buffer and the unit (i.e. 200 ft.)

• Accept all other defaults and click OK.

Geo-processing

Buffer


Clip

• INPUT FEATURES is the shapefile to be clipped.

• CLIP FEATURES is the shapefile that is the boundary of the clip.

• OUTPUT FEATURE CLASS is the new shapefile that will be created. Remember NO SPACES IN FILE NAME.

• OK. The system will process and then give you the choice to add your new shapefile to the map.


Creating & Editing a layer

ArcCatelog - navigate to the folder where you want to save your new shapefile - right click on the folder - New - Shapefile...


Name your shapefile (no_spaces!!!)

point, line, or polygon...

Set the coordinate system of the new shapefile. This coordinate system should match the coordinate system of other layers in your map. Click Edit.

Import shapefile you already have in your map. Go through projected coordinate systems/state plane/ NAD 1983 (US Feet) to find NAD 1983 StatePlane Massachusetts FIPS 2001 (US Feet).prj


Start Editing - Choose the layer - OK

Choose the Construction Tool, and begin drawing on your map.

Double click/ right click - Finish Sketch to complete the shape.

Stop Editing.


Edit & Add info to the Attribute TableRight Click on the layer at the Layer panel - Open Attr Table

Table Option (Top left) - Add field

Right Click on the field we just added - Calculate Geometry


Two ways to select features1. Left click + Shift key on map/attribute table2. Select by attributes

Create layer from selected features

Code Description can be found at the data download page.

Selecting & Exporting Features

gis orsop - home | umass amherst basics.pdf · the real world in this example, our landscape...

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