Geography 241
Lab Activity 2a - Creating and Integrating Shape Files

This lab activity has two distinct parts.  As is normal, you are free to work with one partner on this activity.  In the first part you will get some experience with digitizing and drafting using the drafting and design capabilities of ArcGIS and you will create new attributes for the features you draw.  The second section (part 2b - presented shortly) will allow you to use GPS to survey a small part of the DePaul campus.  Before starting this activity you should read the following sections from the ArcGIS Help system:

• overview of editing process
• Shapefiles, creating
• working with tables

Part A - Creating Shapefiles from Scratch

This first section introduces notions of digitizing (drafting) and the creation of new shapefiles using a georeferenced image as a background.  The intent is to show the way you can create shape files using digital raster graphics as a source document.  In this lab you'll build your understanding of the integration of RASTER and VECTOR filetypes, as well as learn about the creation of new themes and the digitizing interface contained within ArcGIS.  Read the complete lab before you begin.   Use this data for this lab activity.  you will need to open this zip compressed file and extract the data to a folder on your flash drive.  When this is done you can begin the activity.  The files in this folder present a decent beginning as a base GIS for the Lincoln Park Campus of DePaul University.

1. We start by creating the Shapefiles that we will need in the ArcCatalog module (remember that from Lab 1?).  Open ArcMap then open ArcCatalog .

2. In the Catalog, navigate to the folder you copied.  Open the folder and use the file menu to create a new shapefile as seen here:

This will present the Create New Shapefile dialog.  In this dialog you must name the new file and select the appropriate feature type.  You are going to create two shapefiles, one named buildings_new of type polygon, and one named sidewalks of type polyline.  As you are creating these you should select a spatial reference system that matches the reference system used in the image we will be using as a base.  It will work for our purposes here without doing this but if you intend to use this layer with other georeferenced datasets you should do this now.  The coordinate system used in the image file you are using is NAD_1983_UTM_Zone_16N (this can be seen by looking at the Metadata tab of the image layer in ArcCatalog).  You can select the correct reference system as you are creating the Shapefiles by using the "Edit..." button and clicking "Select" then opening Projected Coordinate Systems, UTM, and selecting the appropriate system.

When you have completed this and are satisfied that you know where everything is located in the folder go back to your ArcMap window.

3.  Back in ArcMap, make certain that the Editor Toolbar is open.  If not, use the View - Toolbar menu to open this toolbar:

Here is some basic information about editing features in ArcMap:

You can create three main types of features with the Editor toolbar: points, lines, and polygons.  To create a line or polygon, you must first create a sketch. A sketch is composed of all the vertices and segments of the feature. Vertices are the points at which the sketch changes direction, such as corners; segments are the lines that connect the vertices.  You can create a sketch by creating the vertices and segments that make up the features. Vertices are marked in green, with the last vertex added marked in red.  The Sketch tool is the tool you will use most often to create a sketch. It has an accompanying context menu that helps you place vertices and segments more accurately. The Arc tool, the Distance–Distance tool, and the Intersection tool (located with the Sketch tool on the tool palette) also help you create vertices and segments using other construction methods.

When you're creating a new feature, the target layer determines to which layer a new feature will belong. The Target Layer dropdown list (shown below) contains the names of all the layers in the datasets with which you're working. Subtypes are also listed, if applicable. For instance, if you set the target layer to "Buildings: Commercial", any features you create will be part of the "Commercial" subtype of the "Buildings" layer.  You must set the target layer whenever you create new features—whether you're creating them with the Sketch tool, by copying and pasting, or by buffering another feature.

4.  Open the files in the Lab 2 folder that you copied at the start of the lab activity.  There should be three shapefiles and inside the folder 85256079 there is a georeferenced TIF orthoimage at 1-meter resolution of the Lincoln Park campus in 2002.  The TIF file (85256079.TIF) is is part of the project covering the entire city of Chicago being made available by the USGS.  These files contain georeferencing information that allows them to be referenced to the UTM coordinate system.  The shapefiles are named in a self-explanatory fashion - these are part of the GIS dataset from the City of Chicago.  Feel free to explore these.

A couple of words about images in ArcMap:

An image is a graphic representation or description of an object that is typically produced by an optical or electronic device. Some common examples of image data include remotely sensed data, such as satellite data, scanned data and photographs. Image data is a form of raster data where each grid-cell, or pixel, has a certain value depending on how the image was captured and what it represents. For example, if the image is a remotely sensed satellite image, each pixel represents light energy reflected from a portion of the Earth's surface. If, however, the image is a scanned document, each pixel represents a brightness value associated with a particular point on the document.

Now, add the files that you just created in ArcCatalog to your data frame.  Begin using these to add features from the orthoimages.  Using the Editor toolbar, select the appropriate layer and begin creating features.  You start creating and modifying features by selecting the appropriate task in the Editor task list (see below).  I want you to do two things here:

• Using the buildings_new shapefile, and your knowledge of the area, add polygon features that are the outline or "footprint" of all buildings in the area between Fullerton, Belden, Kenmore, and Racine.
• Using the sidewalks shapefile, digitize the centerline of all sidewalks in this same area.

On the Sidewalks shapefile that you are creating you should use the "snapping" capability of ArcGIS.  This can be accessed and turned on in the Editor menu (seen to the right).  Selecting Snapping... opens a pane where you can turn on this function for vertices, edges, or ends of lines.  Try it out.  If you need more or less tolerance you can set the Snapping tolerance in the Options dialog under the general tab.  A good tolerance is somewhere around 7-10 pixels.  There are some neat tools here - I particularly like "snap tips".  Use snapping to create a really neat (as in clean) sketch of the sidewalks.  If you don't use it I will be able to tell.

Experiment with the different tools to determine how they work and what they do.

The most useful tool for creating features is probably the sketch tool (the little pencil).  Here is some useful information about the editing features in ArcMap used for creating new features:

• 1.      Click the Current Task dropdown arrow and click Create New Feature.

• 2.      Click the Target Layer dropdown arrow and click a line or polygon layer.

• 3.      Click the tool palette dropdown arrow and click the Sketch tool.

• 4.      Click on the map to digitize the feature's vertices.

• 5.      When finished, right-click anywhere on the map and click Finish Sketch.

Tips

• To delete a single vertex from a sketch, center the pointer over the vertex until the pointer changes. Right-click, then click Delete Vertex.

• To delete the entire sketch of the feature you're creating, position the pointer over any part of the sketch, right-click, and click Delete Sketch or press Ctrl + Num Del.

• To finish a sketch, you can also double-click on the last vertex of the feature or press F2.

• You can undo the last vertex you created by clicking the Undo button on the ArcMap Standard toolbar. Click the button again to undo the second-to-last vertex you created, and so on. Click the Redo button if you want to re-add the vertex.

• You can add the shape of a line or polygon feature to the sketch by right-clicking over the feature with the Sketch tool and clicking Replace sketch. The sketch will contain the shape of the feature you clicked over.

When you finish each of your Shapefiles (make sure you save your work as you go along) turn off the image layer in your view by clicking the check box in the table of contents.  Check your new themes by turning the image layer on and off.  Pay attention to where you are saving your files.  Make sure that you study the tables attached to each of the Shapefiles you’ve created, these can be used to attach attributes to each of the shapes in the three layers of data.  I want to remind you that if you need to save your work and take it with you with the intention of opening it again on a lab machine save all of your work including the data folder you downloaded and the new Shapefiles you are creating and editing as well as any "map" files you create in one place, preferably on your flash drive.

Do your best to produce neat work - you can use the lpc_buildings shapefile as a guide, but do your own work.  When you have finished, open the table for each layer and see what you've done.

5.  Having created these shapes, I want you now to edit the table for the buildings shapefile.  Print a black and white copy of your map and take a walk to see how you've done.  Jot on your map the number of stories (floors) for each of these buildings and the name of the building.  Bring these data back into the lab and add two attributes (fields) to the table that will contain the number of stories and the name of the building.  If you don't know the name use the address.  Save all this work on your flash drive, we may want to use it later.

Now, use the LAYOUT interface to create a Layout of your map that includes labels for the buildings.  Your layout should include a north arrow, scale, legend, and title.  Include the orthoimage and the two new shapefiles you have created ONLY.  Lay the map out in "C" size (17" x 22").  Signify your completion of Part a of this exercise by printing the Layout of your map on the Designjet Plotter.

Part a of this activity is due Monday October 12, at the end of class.