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.
  • Bring up ARC/INFO workstation from the START menu.
  • w d:\class\cascade Change directory to the cascade directory.
  • [at Arc: prompt]grid Enter the mode for raster analysis (and display of all features)
  • display 9999 Create a drawing canvas.
  • mapextent dem Define world coordinate window for drawing
  • gridshade dem 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 dem The colors wrap around every 256 meters
  • gridshade dem # linear linear stretch The # is a placeholder for a default argument
  • setwindow * dem The * means click twice with the mouse to select an interesting area. The second argument is just for snapping.
  • demi = dem 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
  • log demi
  • list demi.vat This is interesting. You actually have a grid of pointers into a database file of elevations.
  • Open up a directory window and examine your files. ...
  • 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
  • Create contours. Look up how it's done. Type "help", bring up arcdoc from the start menu. See how 10-meter contours compare to 40-foot contours. Note: it is implied but clearly stated that the elevations in dem are stored in decimeters. Why not call the contour coverages (coverage is a technica term) cont10m and cont40ft?
  • image fortson.tif Draw the USGS quad sheet.
  • slope If you need more information, type help to launch the online manual.
  • sloppy = slope(demi,.1,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.
  • quit out of the grid module
  • quit out of ARC/INFO