MULTIPLE  FOR RASTER FILES

GRASS GRASS user
1

Hi.

I need to represent multiple attributes in GRASS raster files.
For example, surface roughness, dielectric constant, veg. cover, etc.
I can think of two ways to do this:

  1. create multiple raster maps for the terrain, one for
     each attribute. The attribute in each file stores the value
     for the original attribute.

  2. have the single attribute in the raster file store the
     values of all the attributes after encoding them, e.g.
     the first digit in the attributes represents roughness,
     the second, veg. cover, and so on.

I can understand that the second method is extremely dirty in terms
of simplicity, expandability, etc. But I would like to know if anyone
has tried it. ANY other comments are welcome.

-Raj

__________________________________________________________________

MOBILE AND PORTABLE RADIO rajguruc@vttcf.cc.vt.edu
  RESEARCH GROUP raj@mprg1.mprg.ee.vt.edu
Dept. of Electrical Engg. (703) 231-4160
VPI&SU
__________________________________________________________________

2

In a personal reply to <rajguruc@vttcf.cc.vt.edu>, what I consider
a minor shortcoming of GRASS came up.

If you've already got #1 done, then you may run into another problem
if trying to consolidate all maps into one. r.cross, again IMHO, is
brain-dead. When you make the cross, it puts filenames and category
numbers intead of attribute values in the consolidated map.

I wrote a shell script which fixes this (which is painfully slow), but
may I propose a better fix? Would anyone be interested in a command
line option to r.cross which, instead of putting layer names and
category numbers in its output, puts the original attribute? Has anyone
addressed this? Does anyone want to? (It should be only a hour or two
of code changes.) Is anyone against this?

This small change makes life a whole lot easier sometimes.

James Darrell McCauley Department of Ag Engr, Purdue Univ
mccauley@ecn.purdue.edu West Lafayette, Indiana 47907-1146