An exercise to introduce ARC/INFO with grid data structures

This exercise uses ARC/INFO software. Many commands are (very) peculiar to ARC/INFO. Clever students will use a mouse to cut and paste commands from this page to their command windows. It beats the socks off the GUI.
  • log into cliff in X-windows as user class. (Ask Harvey for the password.)
  • mkdir mydir make a temporary directory (give it a unique name)
  • echo $DISPLAY If X-windows does not want to write to your display, set it straight.
  • xterm& Now can can copy and paste from this window (if your X server is supporting Motif correctly).
  • cd mydir
  • arc Congratulations, you are in ARC/INFO
  • [at Arc: prompt]grid Enter the mode for raster analysis (and display of all features)
  • display 9999 Create an X-windows canvas. This command has nothing to do with unix DISPLAY.
  • mapextent ../sub Define world coordinate window for drawing
  • gridshade ../sub elevation = 1 -> white, elevation = 2 -> red ... elevation = 17 -> white, etc. What's wrong with this picture?
  • shadeset rainbow a built-in set of 256 colors
  • gridshade ../sub The colors wrap around every 256 meters
  • gridshade ../sub # linear linear stretch The # is a placeholder for a default argument
  • setwindow * ../sub The * means click twice with the mouse to select an interesting area. The second argument is just for snapping.
  • demi = ../sub This is almost as simple as map algebra can get. It is non-trivial because you have set a non-default analysis window.
  • lg or listgrids for the verbose
  • describe demi
  • list demi.vat This is interesting. You actually have a grid of pointers into a database file of elevations.
  • &sys ls -l * ARC/INFO precedes every ArcMarcoLanguage keyword with an ampersand. You are simply submitting an operating system command to list all files. Note that your workspace looks different to unix than to the ARC/INFO environment.
  • gridshade demi # linear You created this grid. Enjoy it.
  • mapextent demi Reset your area of drawing interest.
  • gridshade demi # linear You can always type clear if you want
  • arcs ~topog/areas/alleg/contours and there are hundreds of things we can do with points, lines, and polygons.
  • slope If you need more information, type help to launch the online manual.
  • sloppy = slope(demi,.3048,PERCENTRISE) You have a grid of slopes.
  • gRiDshAde sloppY # LINEAR I am just emphasizing the fact that ARC/INFO is mostly case-insensitive.
  • mushy = focalmean(demi) ARC/INFO is not a real image-processing package, but it can do this. How would you list the many useful arguments of the focalmean function?
  • mape * Pick a small area.
  • gridshade demi Look at your DEM.
  • gridshade mushy Compare to the smoothed version.
  • cellvalue sloppy * Click on a point to read it's slope. The grid does not have to be visible to be accessed.
  • &workspace .. Change workspace. (A workspace is a directory with ARC/INFO stuff.)
  • &run model Start Harvey's fancy macro.
  • click on RUN MODEL Calculate critical rainfall. How much rain (percolating through the soil and concentrating in the hollows) does it take to make an area fial?
  • adjust a parameter slider Design a soil. Note: soil depth of -1 is a flag for measured non-uniform depth.
  • click on RUN MODEL Some grids have been precalculated. Some are being created.
  • type "1" after "Run:"
  • click on "plot left" Your result appears on the left side of the window.
  • Type "2"
  • click on "plot right" and on the right side.
  • Continue to fool around Experiment. You probably cannot break anything.
  • click on "Clean and Quit" Be neat.
  • quit out of the grid module
  • quit out of ARC/INFO
  • cd .. get out of tess
  • rm -fr tess Delete your test files.
  • logout leaving unix