>From grass-lists-owner@max.cecer.army.mil Fri Dec 4 07:39:13 1992
Date: Fri, 4 Dec 92 07:29:14 CST
From: grass%alla@amber.cecer.army.mil (grass)
Message-Id: <9212041329.AA08398@alla>
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To: grassu-list@amber.cecer.army.mil
Subject: Re: ERDAS to GRASS conversion
Cc: grass%alla@amber.cecer.army.milThe ERDAS to GRASS conversion can be relatively straight forward.
If the ERDAS file (either GIS or LAN) is in the 7.3 format (cvt73) and is 8 bit data then use r.in.erdas. I've had much success with this.
If this is not the case then it can be a bit more difficult but not much.
With ERDAS 7.5 the DPDATA command will allow the user to write the output
to a file.
If the Erdas file is a GIS file either BIL or BSQ will work.
For a LAN file use BSQ. The resultant file will have a .blk extension.
Move this file to the GRASS cell directory.
Edit a header file in the cellhd directory to match the output from LISTIT with
the compression set to 0.
for 8bit files the format is 0 for 16bit files the format is 1
The file is now ready for r.support.
The GRASS file will have exactly the same data as the ERDAS file._____________________________________________________________________
| |
| Tom Nelson |
| Corps of Engineers |
| Fort Worth, Texas |
| (817) 334-2095 |
|____________________________________________________________________|
I agree with Tom's point that "r.in.erdas" works fine and pretty straight
forward. There are several alternatives you can make ERDAS to GRASS conversion,
including r.in.erdas (7.3 format), r.in.sunrast (7.4 format), r.in.ASCII (read
ERDAS DATATAB ASCII output) and direct conversion from ERDAS DPDATA output (as
Tom indicated in his mail).
If "r.in.erdas" doesn't work on your site, I prefer to use DPDATA command to
convert ERDAS data into GRASS, and I think it works very dependable. Tom
introduced a straight forward way to convert data, but I think the way he
described is to convert a single band file (either GIS or LAN file). When ERDAS
converts its GIS (always single band) or LAN files to BLK files, they could be
in BIL or BSQ or BIP format without any header records in them. The ".blk"
format is a file format just as the raw tape format without header. When data
converted from LAN to BLK format, it could contain multi-band data. The way Tom
described to convert data from ERDAS to GRASS will work fine with any GIS file
and single band LAN file if I understand it correctly. However, by using GRASS
"i.tape.other" command (you can read a disk file instead of tape), you could
read multi-band ERDAS ".blk" file directly with either BSQ or BIL formats, GRASS
will handle this file as an image group, that will give you some flexibility to
deal with ERDAS data. All information you need to run "i.tape.other", could get
from the output of ERDAS LISTIT command.
****************************************************************************
# # ## # # #### Wang Song (wang)
# # # # ## # # # Research Assistant
# # # # # # # # Center for Advanced Spatial Technologies
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## ## # # # ## # # University of Arkansas
# # # # # # #### Fayetteville, AR 72701
INTERNET: wang@spock.uark.edu Tel: (501) 575-6159
- or - wang@kirk.uark.edu FAX: (501) 575-3846
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