GEOG 485:
GIS Programming and Software Development

Project 1, Part II: Creating contours for the Fox Lake DEM

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The second part of Project 1 will help you get some practice with Python. At the end of Lesson 1, you saw three simple scripting examples; now your task is to write your own script. This script will create vector contour lines from a raster elevation dataset. Don't forget that the ArcGIS Desktop Help can indeed be helpful if you need to figure out the syntax for a particular command.

Earlier in the lesson you were introduced to the Fox Lake DEM in your Lesson 1 data folder. It represents elevation in the Fox Lake Quadrangle, Utah. Write a script that uses the Contour tool in the Spatial Analyst toolbox to create contour lines for the quadrangle. The contour interval should be 25 meters and the base contour should be 0. Remember that the native units of the DEM are meters, so no unit conversions are required.

Running the script should immediately create a shapefile of contour lines on disk.

Follow these guidelines when writing the script:

  • The purpose of this exercise is just to get you some practice writing Python code. Therefore, you are not required to use arcpy.GetParameterAsText() to get the input parameters. Go ahead and hard-code the values (such as the path name to the dataset).
  • Consequently, you are not required to create a script tool for this exercise. This will be required in Project 2.
  • Your code should run correctly from PythonWin. For full credit, it should also contain comments, attempt to handle errors, and use legal and intuitive variable names.

Deliverables

The deliverables for Project 1 are:

  • The .tbx file of the toolbox containing your Part I model. The easiest way to find it is to right-click your toolbox in the Catalog window, click Properties, and note the Location. If you can't browse to this path in Windows Explorer, you'll need to enable the Windows option to show hidden files and folders.
  • The .py file containing your Part II script.
  • A short writeup (about 400 words) describing how you approached the two problems, any setbacks you faced, and how you dealt with those. These writeups will be required on all projects.

Successful delivery of the above requirements is sufficient to earn 90% on the project. The remaining 10% is reserved for efforts that go "over and above" the minimum requirements. For Part I, this could include (but is not limited to) meaningful labels on and around model elements, analysis of how different input values affect the output, substitution of some other interpolation method instead of IDW (for example Kriging), documentation for your model parameters that appears in the side-panel help, or demonstration of how your model was successfully run on a different input dataset. For Part II, in addition to the Contour tool, you could run some other tool that also takes a DEM as an input.

As a general rule throughout the course, full credit in the "over and above" category requires the implementation of 2-4 different ideas, with more complex ideas earning more credit. Note that for future projects, we won't be listing off ideas as we've done here.  Otherwise, it wouldn't really be an over and above requirement. smiley

Finishing Lesson 1

To complete Lesson 1, please zip all your Project 1 deliverables (for parts I and II) into one file and submit them to the Project 1 Drop Box in Canvas. Then take the Lesson 1 Quiz if you haven't taken it already.