Dear Grass Users,
importing Ascii-File to Erdas Gis - exporting as Grass -File
I have created a map (DEM) in Erdas by reading an ASCII-File. The
data type is Float Single and the projection is Transverse Mercator.
Exporting this map as a Grass-file, Erdas gives the warning that
float data can only be exported as integer.
If I accept and create a location and mapset it can only be imported
into Grass without any projection (plane) although it is exported as
Transverse Mercator.
1. Is Grass not able to manage float data maps ?
2. How can I save the projection TM during the transfer from Erdas to
Grass ?
Stephan
********************************
Dr. sc. agr. Nicola Fohrer
Wissenschaftliche Assistentin
Institut fuer Landeskultur
Senckenbergstr. 3
35 390 Giessen
Tel:0641/99 37385
Fax:0641/99 37389
email:Nicola.Fohrer@agrar.uni-giessen.de
From: "Nicola Fohrer" <Nicola.Fohrer@agrar.uni-giessen.de>
I have created a map (DEM) in Erdas by reading an ASCII-File. The
data type is Float Single and the projection is Transverse Mercator.
Exporting this map as a Grass-file, Erdas gives the warning that
float data can only be exported as integer. If I accept and create a
location and mapset it can only be imported into Grass without any
projection (plane) although it is exported as Transverse Mercator.
1. Is Grass not able to manage float data maps ? 2. How can I save
the projection TM during the transfer from Erdas to
Grass ?
GRASS is unable to use floating point maps unless you have compiled
in the floating point extensions. I seem to recall one of the Solaris
compiles has them compiled in, but I don't know.
The TM projection is set when you create the location, not when you
import a file.
Good Luck!
Angus Carr.
Nicola Fohrer wrote:
Dear Grass Users,
importing Ascii-File to Erdas Gis - exporting as Grass -File
I have created a map (DEM) in Erdas by reading an ASCII-File. The
data type is Float Single and the projection is Transverse Mercator.
Exporting this map as a Grass-file, Erdas gives the warning that
float data can only be exported as integer.
If I accept and create a location and mapset it can only be imported
into Grass without any projection (plane) although it is exported as
Transverse Mercator.
1. Is Grass not able to manage float data maps ?
2. How can I save the projection TM during the transfer from Erdas to
Grass ?
Stephan
********************************
Dr. sc. agr. Nicola Fohrer
Wissenschaftliche Assistentin
Institut fuer Landeskultur
Senckenbergstr. 3
35 390 Giessen
Tel:0641/99 37385
Fax:0641/99 37389
email:Nicola.Fohrer@agrar.uni-giessen.de
My experience with GRASS is somewhat limited, but I can tell you for
certain that a GRASS raster file can only be an integer type. For my
data sets, where the float value is very important, I pre-process the
ASCII data by mulitplying such that the floating point becomes an
integer which contains all necessary values. For example, 25.9 bcomes
259 - I also have to adjust my standardized color scale (in the colr
directory) and my category file to accomodate this change. Hope this
info will be useful to you.
Sharon Mesick
mesick@dolphins.ssc.nasa.gov