I am a research assistant at the University of Houston Clear Lake.
I am currently working on a project that involves GRASS. I need to know
the following question regarding GRASS. If this is not possible to answer
please be kind enough to refer me to someone who can answer the question
below.
QUESTION: 1) What is the data structure used inthe GRASS data file. In
other words how is the data stored
2) What compression technique is used to compress the data files in GRASS.Thanking You
Shameek
This is a very simplistic answer, but will hopefully get you started.
Raster, site and vector files are handled differently in GRASS.
Raster files are either compressed or uncompressed. Uncompressed
raster files are just plain ascii values stored in a row by column
method. I think compressed raster files are stored using a
RLE (run length encoded) method. There are library routines in grass
to read both as well as to compress/uncompress as needed.
I do not know about the vector files. Sites files are just
ascii tables using the correct column delimiters.
Ken Sibley
USDA-SCS "Hell, if you understand everything I say,
ksibley@ncg.scs.ag.gov you'd be me!" - Miles Davis
----- End Included Message -----
From grass-lists-owner%max.cecer.army.mil@munnari.oz.au Wed Jun 8 07:59:17 1994
Date: Tue, 7 Jun 94 15:40:34 CDT
From: ksibley@ncg.scs.ag.gov (Ken Sibley)
Sender: grass-lists-owner@max.cecer.army.mil
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Subject: Re: grass
Cc: grassp-list@max.cecer.army.mil
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> I am a research assistant at the University of Houston Clear Lake.
> I am currently working on a project that involves GRASS. I need to know
> the following question regarding GRASS. If this is not possible to answer
> please be kind enough to refer me to someone who can answer the question
> below.
> QUESTION: 1) What is the data structure used inthe GRASS data file. In
> other words how is the data stored
> 2) What compression technique is used to compress the data files in GRASS.
>
> Thanking You
> Shameek
>
This is a very simplistic answer, but will hopefully get you started.
Raster, site and vector files are handled differently in GRASS.
Raster files are either compressed or uncompressed. Uncompressed
!! raster files are just plain ascii values stored in a row by column
=======================
method. I think compressed raster files are stored using a
RLE (run length encoded) method. There are library routines in grass
to read both as well as to compress/uncompress as needed.
I do not know about the vector files. Sites files are just
ascii tables using the correct column delimiters.Ken Sibley
USDA-SCS "Hell, if you understand everything I say,
ksibley@ncg.scs.ag.gov you'd be me!" - Miles Davis
Uncompressed raster files are BINARY not ASCII ! Values in raster files
may be byte,integer*2 or integer*4.
Rod Paterson
Aberfoyle Resources Ltd
Phone: 61-3-8822226
Fax: 61-3-8131086
Email: rgp@aberfoyle.oz.au