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University of Nebraska–Lincoln


Purpose

In this activity, you will create a surface profile using a raster grid and elevation values. This surface profile will help you analyze the topography of an area.


Background: Remember

Raster grids are composed of separate bits of data. Each piece of data has a measured value.


Materials:

  • Macintosh Computer
  • ClarisWorks Software (or other word processor)
  • NIH Image Software


Procedure:

  • 1. Open a word processing file in ClarisWorks. Enter the following elevation values, in order, reading "across each row." Remember, you must "space once between each value."

    100-110-110-100-80

    100--90--70--80--80

    100--90--60--70--80

    100--80--40--70--90

    100--60--20--50--70

  • 2. Select "Save as" from the File Menu. From the ClarisWorks window, pull down and select "Text." Now, name your work and add ".txt" to the end of the name. Quit ClarisWorks.
  • 3. Open the NIH Image software and follow the directions from Activity 1-Creating a Simple Raster to create your raster grid.
  • 4. Once you have your raster grid for the elevation values, select "Surface Plot" from the "Analyze" Menu and click "OK."
  • 5. At this point, answer questions numbered 1, 2, and 3 from the "Discussion" section.
  • 6. Looking at the screen, notice the "Tools Palate" shown down the left side. To measure distance, "click" on the "Measuring Tool."
  • 7. In order to measure distances using this tool, click on the icon and draw a line whose distance you can use to set a scale. For this practice any line drawn on the surface profile will do. Practice drawing lines.
  • 8. When you are ready to set a scale, draw a line, select "Measure" from the "Analyze" menu. Now, select "Set Scale" from the "Analyze" menu. Choose "Miles" and fill-in the "known distance as 1."
  • 9. Now watching the data displayed in the "Lower Left" corner of the screen, practice measuring distances.
  • 10. Another useful tool is the angle tool. Try clicking on its icon and then again watching the data in the lower left of the screen, practice measuring angles found on your surface profile.
  • 11. A summary of all your measurements can be found by selecting "Show Results" from the "Analyze" menu.
  • 12. Now, complete the rest of the questions in the "Discussion" section below.

  • Discussion: Copy and answer on you own paper.

  • 1. Using the surface plot, explain how rainfall would drain off the land in this region.
  • 2. Where are the highest elevations located?
  • 3. If you could look at an aerial photograph of this area, what would you expect to see?
  • 4. Describe how the "measuring tool" could be used to analyze surface profiles.
  • 5. Where on your surface profile is the steepest slope? What was the angle of this slope?