MULTIPLE ATTRIBUTES FOR RASTER FILES

[Jerry Thompson]

> 
> > 
> > 
> > 
> > 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
> > 
> 
> We are currently working on a GRASS-RDBMS interface which will enable
> multiple attributes to be associated with either raster/vector or
> polygonal features. The current version of the interface is designed 
> to be used with INFORMIX RDBMS products. However, the software 
> design has been developed with an ey towards easy implementation
> with any ANSI SQL product. The beta release for this code will be 
> decided during the users group meeting in Denver. I expect that
> a date in June or July is realistic for Beta code.
> 
> jaf
> 
> 
> ==================================================
> 
>  James A. Farley	email: jim at moray.uark.edu
>  Technical Director
>  CAST			voice: (501)-575-6159
>  University of 		fax:   (501)-575-3846
>  Arkansas
>  Fayetteville, AR 72701
> 
> ==================================================
> 
Currently we distribute teh SQL-like dbms RIM with GRASS. Using it (you will
need a Fortran compiler) you can access multiple attributes. It is fairly easy
to write shell scripts that use RIM and v(s).db.rim. One such is:

#!/bin/sh

# usage: dbqueryi data-base vect-map normal-color highlight-color

dbname=$1
file=$2
ncolor=$3
hcolor=$4

d.vect $file c=$ncolor

while true
do
echo
echo "Select a point on the graphics screen with the mouse..."

set `d.where -1 | tr "." " "`

echo "Getting the record from the data base and highlighting the vector..."

v.db.rim $dbname <<EOF
.output /dev/null
.find
$1 $3  1
.vector_map temp.vect
y
!d.vect temp.vect c=$hcolor >/dev/null
.output
.print
.output
.ex
EOF

echo
echo "Enter Q to Quit:"
echo "or ENTER to continue"
read line
d.vect temp.vect c=$ncolor >/dev/null

if [ "$line" = "Q" ]
then
        exit
fi

done


You use v.db.rim to build the data base. It will work with either polygonal,
line, or site vector files, or site_list files.


Jerry Thompson
Spatial Analysis Systems Team, USACERL