Erdas to grass conversion

[grass]

Erdas .gis files have a 128 byte header at the front of the file that contains 
the information pertaining to rows, cols, coordinate system etc. The rest of thefile follows also in 128 byte 'rows' and the last row is filled making the file slightly larger than rows*cols. 
Erdas image files are set in a BIL format 'Band Interleaved by Line', also in a 128 byte 'rows'.
the .gis files can be converted to gras by stripping off the header and 
reblocking the file. 
The only way I've found to deal with multiple band image files is to subset themout to their individual bands and convert the bands seperately. The informationfrom the ERDAS command LISTIT is helpfull in providing the rows and cols and 
color information  .
after the gis file is converted r.support must be run on it to make it complete.
I've included a short file that convert erdas .gis files to a grass cell file
without support 

this works for erdas  .gis 8bit files.



dd if=$1.gis ibs=128 skip=1 of=tmp.tmp obs=$2
dd if=tmp.tmp of=$1 bs=$2 count=$3
rm -f tmp.tmp

where $1 is the name of the .gis file without the  .gis extension
      $2 is the number of cols
      $3 is the number of rows

for 16bit single band (DEM) files 


rows=`expr \( 2 \* $3 \)`
dd if=$1.lan ibs=128 skip=1 of=tmp.tmp obs=$2
dd if=tmp.tmp of=tmp2.tmp bs=$2 conv=swab
rm -f tmp.tmp
dd if=tmp2.tmp of=$1 bs=$2 count=$rows
rm -f tmp2.tmp

the conv=swab is not always needed. it depends on the data
I know these are clumsey but they work 
and they are not too slow 
any improvements would be appreciated 

Tom Nelson
U.S. Army COE 
Fort Worth Texas