FREC 682 Spatial Analysis

The GRASS CELL Monitor

The CELL monitor writes display commands to a GRASS raster file called D_cell in your current mapset instead of to a visible display monitor. It's basically a primitive screen dump utility. The GRASS installation on Strauss only has one CELL monitor. To use it, define its size in cells before starting your GRASS session, i.e.

	setenv GRASS_HEIGHT 400
	setenv GRASS_WIDTH 800

When you start the CELL monitor with the d.mon command, you won't see a display device. Any display modules you execute will "paint" to this invisible device. When you have displayed the things you want, use d.mon to stop the CELL monitor. At this point it writes a raster map called D_cell to your mapset. Open a conventional display monitor, change your region to this map with g.region rast=D_cell, erase the display monitor and display D_cell with d.rast. CELL is most useful for creating 3D images including vector lines (roads and streams) superimposed on a raster image.

The old GRASS p.map utility is not supported by any hardcopy devices available from Strauss.

The GRASS ps.map utility generates Postscript files for printing to any Postscript-capable printer, and has largely displaced the p.map utility. You can run it interactively (where its capabilities are limited), or via scripts. Use the -r flag for landscape orientation. See the attached notes and manual pages for script commands. ps.map can generate the highest-quality cartographic output of any hardcopy utility discussed here. However, ps.map does not support printing of graphics from d.3d or d.histogram.

Associated GRASS Postscript modules include ps.icon, which lets you create your own icons for mapping site features, and ps.select, which lets you select which of several hardcopy devices or formats you want to print to. (These device drivers are easy to write, but CNS has not actually created any. The default device is standard 8.5x11 format.)

ps.map:

The GRASS module ps.map creates a postscript file which you can send to any postscript device.

The usual format is:

 	ps.map [-r] input=scriptfile output=mapfile.ps 

The r flag rotates the map to landscape orientation.

Use a text editor to create a scriptfile of ps.map commands e.g.:

 scale 7.5 inches
 rast elevation.dem
 maploc 1.3 1.0   (upper L corner of map)
 header
   file map.hdr   (separate title file)
   font HelveticaBold
   fontsize 14
   end
 colortable y
   where 8 1
   font HelveticaBold
   fontsize 7
   end
 vect streams
   color cyan
   width 1
   end
 vect roads
   color black
   width 1
   end
 ...   

Run ps.map using this input file.

Don't forget the -r flag if you want a landscape orientation. Since output files typically get big enough to choke your home directory disk allocation, direct the output file to

	/home/strauss/usrb/grass.data/print  

But please remember to erase your files as soon as you have your hardcopy! To view your file on the screen use Ghostscript:

 	gs mapfile.ps

For the color laser printer in the basement of Smith:

1. Remember to keep everything in the file within the printer's margin limits (maploc command in script, etc.):

   L=1.3" R=0.8" T=0.2" B=0.2" (landscape)

   T=0.8" B=1.3" L=0.2" R=0.2" (portrait)

2. Send it to the printer:

   qpr q smicolps mapfile.ps