GIS Survey Class
 

Assignment 5: Screen Digitizing to create a new feature map from an image theme (updated 10/29/2008)

I realize that for some of you this seems like a lot of materials being presented. However, do your best. If you have problems turn-in whatever you managed to complete.

Assignment Requirements:

Part 1: Activities

1. Digitize at least 2 polygons, 2 lines, and 2 point features and convert them to shapefiles. These features can be anything within the bounds of the aerial photos (data location is J:\GEO\GEO_data\BHAM\AirPhoto_Bham\1997_color  (we used r380331.jpg) or feel free to cruise the other air photos for Bellingham or anywhere else (check with me if you want to go outside of the Bellingham data) – make sure in ArcView that the "data source types" are set to "image data source" – this tells ArcView to look for raster based images) and also that you have the Jpeg Extension turned on. (see PowerPoint notes for help).

Extra Credit:  Those that would like 5pts extra credit can use an air photo as a base map for a field study.  Print out the air photo then go out to the location and add your new "data" directly to the photo (things that are currently not on the photo).  Bring that back to the lab and eyeball it in by digitizing onto the original jpeg photo at your computer screen.  If you have questions regarding this please come see me.

2. Make a complete map showing all six shapefiles by using the Layout command. Make sure that all shape files stand out (i.e. the lines are thick enough, points large enough... to see in the printed copy of the layout use translucent colors for your polygons). Also, be sure under View/Properties to set the Map Units to feet and also the Distance Units to feet if using the 1997 data set.  Place a second inset map in your final Layout with only the digitized materials clicked on.  That means you will have a main map with both your air photo and vector data and second in-set map that only shows the vector data (air photo not included).

Part 2: Write Up

1. Definitions (in your own words provide definitions and discussion for each of the following):

• On screen digitizing - What is it and what is it used for?
• Shape files – What are they? How are they used? (see Some Definitions on the Web Page to learn about this)
• Image files -- What are they? How do they differ from shape files?

2. Objective:

• What is the purpose of your map?
• What features will you digitize? Why these?

4.  Final Map: From your Layout, create a very neat, concise, complete and clear final map and include a second map as an inset that contains only your digitized points, lines and polygons.  (If you can't get the inset to work then you can make this second map as a second layout).

5.  Results and Discussion:

• What are your results? Discuss, describe, explain...

 

6.  Critique:

• Are the results what you expected?
• Did you have any problems?
• How could you improve your map?

7.  Store an electronic copy of your Layout:  In the following location -- J:\saldata\SAL_temp\Egeo250 -- maps for posting\Layouts from Digitizing Assignment\ place a copy or your final layout map in a jpeg format.  The file name for your layout should be: egeo250-your last name-digitizing   for example: egeo250-buckley-digitizing.jpg

8. ProcLib: Write a short ProcLib for inserting a second map onto a Layout.

9. EXTRA CREDIT  Add some attribute data to your digitized data, and make a layout with the attribute data inset into the final layout.