Heads up Digitizing

Introduction to Heads-up Digitizing

Follow these steps to digitize the roads around CSUF.

Start

If you haven't already done so:

You can build pyramids if you like.

You should see an air photo of the campus. Use the air photo as a guide to digitize the roads.

The image is projected in UTM Zone 11 NAD83 coordinates, but because spatial reference information is missing for this data, you could set the map units and display units to meters (as we did way back in Project 1). However, a better approach that will minimize "excitement" when you combine all your layers at the end is to run the Define Projection tool on csuf.tif before you continue.

Open the ArcToolbox by clicking the ArcToolbox button on the menu
Click the + next to Data Management Tools
Click the + next to Projections and Transformations
Double click the Define Projection tool
Select csuf.tif from the Input Dataset or Feature Class dropdown list
Click the button to the right of the Coordinate System box to open the Spatial Reference Properties dialog

Now enter the information about the existing coordinate system (this is where accurate and complete metadata comes in handy).

Double-click Projected Coordinate Systems
Double-click UTM
Double-click NAD 1983
Highlight NAD 1983 UTM Zone 11N
Press OK twice
Close the Define Projection dialog, if necessary, when processing has been completed

You have defined the projection for the raster layer. However, no .prj file was created since the projection data for this type of raster file is stored in the header of the .tif file itself. See when it was last modified.

Another important thing to note is that the coordinate system for the Data Frame has defaulted to "unknown." Use one of the techniques discussed in class to resolve this before going on.

Create a new shapefile for heads-up digitizing

In order to add the roads to a shapefile, you need to create a new, empty shapefile in ArcCatalog. ArcCatalog is the application within ArcGIS that allows you to browse, organize, and document your data. This is also where you create new empty tables or shapefiles. You can access ArcCatalog functions directly within ArcMap.

Open the Catalog window by pressing the Catalog window button on the menu.
Click the + next to Folder Connections
If you do not see C:\temp, click the Connect to Folder button and browse to it.
Right-click on the c:\temp directory
Select New - Shapefile
Name the new file Roads
Feature Type should be Polyline
Click the Edit button and set the Spatial Reference Properties to UTM as above
Press OK
Exit Catalog window if necessary

Add the empty Roads.shp layer to your data frame if it wasn't added automatically.

Open the attribute table for roads.shp
Add a new field in the table to indicate the name of the road (Select ‘text’ for type and make sure it is wide enough to accommodate the longest road name)
Move the table to a convenient location on the screen so that when you finish digitizing a road you can easily enter its name on the attribute table.

Open the Editor Toolbar by pressing the Editor Toolbar button on the menu.
On the Editor Toolbar Click Editor - Start Editing
Open the Create Features and Constructions Tools window(s) by clicking the last button on the right of the Editor toolbar
Click on Roads in the Create Features window
Then click on Line in the Construction Tools window
Back on the Editor toolbar make sure the Straight Segment tool is selected.

Snapping

Before digitizing any roads, we have to tell ArcMap that when we draw nodes in the same area, we want them to ‘snap’ together.
By default, the Snapping environment may not be appropriate for our project. We need to adjust the snapping functions.
Open the Snapping toolbar: Customize-Toolbars-Snapping
Click Snapping and make sure Use Snapping is enabled
Turn off Edge Snapping leaving the other three types on
Close the Snapping toolbar

Edit Table/Add Features

Use the Straight Segment tool to draw a line representing State College Blvd.
Click to enter each vertex. Be sure to make a vertex/node at any intersections
When digitizing the last vertex, double click to finish
Double click in the street name cell for the new feature and type State College Blvd in the name field. Then press <enter>
Next, you will draw Nutwood Ave. Since Nutwood intersects State College, make sure you move your cursor within the snapping distance of the State College node so the streets will intersect properly. NOTE: The nodes will snap together as you move the cursor to within the snapping distance and the tool tip will appear.
Activate the table window and add Nutwood Ave to the name field
Add the remaining roads bounding campus including the 57 freeway (hey, maybe you want to add another attribute field so you can classify roads vs freeways), following the steps above
When you are finished, STOP EDITING – and YES, you want to save your edits.

Bug Alert: There seems to be an annoying bug at this point in the editing process that was in ver. 9 and still exists in 10. You might have noticed that when you stopped editing one of the records in your data table disappeared. Try closing the Attribute Table and then open it again. If all your data is not there, contact your instructor.

You have successfully created a line layer of the roads around CSUF!

Make sure you save this new shape file to your external storage location before you clear temp again.