[GRASS-user] Export of GeoTIFF

Wed Oct 10 18:56:43 EDT 2007

GRASS Data To ArcView
This document will show the procedure to export GRASS raster and vector data to
ArcView.
GRASS Vector Data to ArcView 2.1/3.0
1) In GRASS use the v.out .ascii command on the vector file you wish to export.
2) In GRASS use the v.out.dxf command on the ascii file you created above. When
GRASS prompts you for a dxf file name, type in the name with extension(i.e.
soils.dxf). The .dxf extension will be needed for ArcView.
Please note that dxf files can only be displayed in ArcView 2.1(MS Windows) and
ArcView 3.0(UNIX and MS Windows).
3) To display the dxf file in ArcView you first need to open a VIEW then add a
theme(Feature Data Source). The dxf file should be selectable on the screen. Open
the dxf file. You have to convert the dxf file to a shapefile in order to change
projection etc.
GRASS Raster Data To ArcView 2.1/3.0
This procedure will georeference a raster image within ArcView!
1) In GRASS use the r.out.tiff command on the Raster file you wish to export. Use
defaults for the command! In particular DO NOT use the LZW compression! This
may make your file unreadable in ArcView. The GRASS generated TIFF file should
have a tiff extention(i.e. photo1.tif)
2) After making the TIFF file goto your "cellhd" sub-directory!
3) Cat the raster cellhd file you exported! You will use the information in this file to
build a world file. A world file is a ascii file ArcView uses to georeference information
for the TIFF file you created. With the world file your TIFF file will be georeference in
ArcView.
4) Start a vi session, name the file the same as your TIFF file except with a different
extention! Use the extention .tfw (i.e. photo1.tfw ). You will enter six lines of
information in your vi session. You can use this file as a base for future world file.
Below is the possible contents of a typical world file.
10.0
0.0
0.0
-10.0
590005
4927995
Below is the possible contents of a typical GRASS cellhd file.
proj: 1
zone: 16
north: 4928000.000000
south: 4914000.000000
west: 590000.000000
east: 609000.000000
n-s resol: 10.000000
e-w resol: 10.000000
format: 1
compressed: 0
Below is the information you will need to create the above world file(tfw). Please note
that the world file contains information in your GRASS cellhd file! Information on the
world file can be found in ArcView 3.0 manual on page 301.
World File GRASS Cellhd File Description
10.0 "e-w resol:" Size of pixel in x direction.
0.0 N\A Rotation term for row(usually 0).
0.0 N\A Rotation term for column(usually 0).
-10.0 "n-s resol:" Size of pixel in y direction(- sign is needed!)
590005 "west" + 1/2 "e-w resol" The x coordinate of pixel in upper left corner. *
4927995 "north" - 1/2 "n-s resol" The y coordinate of pixel in upper left corner. *
Pixel 1,1 * ArcView georeferences the center of the pixel while GRASS
uses the NW edge in the cellhd file. Thus a slight adjustment is
needed to correctly georeference a TIFF file in ArcView. For these
lines you need to add one half the pixel resolution(west) and subtract
one half the pixel resolution(north).
5) Place your TIFF and world file in the same directory. These files now can be used
in ArcView and should be georeferenced correctly!.
A sample world file call be found at the NCG FTP Site! The NCG FTP is listed below.
ftp.ftw.nrcs.usda.gov (goto the /outgoing directory! and get the file "base.tfw")
If You have any questions please contact me at your convenience.
Tony Kimmet
(817)-334-5212 x3062
tkimmet at ftw.nrcs.usda.gov

Michael Barton <michael.barton at asu.edu> wrote:Re: [GRASS-user] Export of GeoTIFF     ESRI needs special GeoTiff options to be enabled. These are documented on the r.out.gdal manual page--near the bottom where I missed them too awhile back.

 Michael

 On 10/9/07 11:58 PM, "christian.braun at tudor.lu" <christian.braun at tudor.lu> wrote:

 Dear list, 

 I have serious problems exporting GRASS DCELL rasters to GeoTIFF. 
 I used r.out.gdal with type=Float32 and set the compression to LZW. 
 What I got later on in ArcView 3.3 is pure noise fort he picture and in ArcGIS 9.2 I get some strange results. 
 The NULL values of the picture get a cryptic code like -1#QUAN1 and if there are pixels with value 0 they become NoData in ArcGIS. 

 I need to have them as GeoTIFFs for the easy im- and export. I am aware that I can also use r.out.ascii but then I have to do an import procedure in ArcGIS. For nearly 1000 images that is a bit hard to do. 

 Any hints for the export options? 

 Thx in advance, 
 Christian 

 _________________________________________

 Dipl. Geogr. Christian Braun
 Tel: +352- 425991-608
 Mobil: +49-179-6845896
 Mail: christian.braun at tudor.lu

 Resource Centre for Environmental Technologies,
 Public Research Centre Henri Tudor,
 Technoport Schlassgoart,
 66 rue de Luxembourg,
 P.O. BOX 144,
 L-4002 Esch-sur-Alzette, Luxembourg

 __________________________________________
 Michael Barton, Professor of Anthropology
 Director of Graduate Studies
 School of Human Evolution & Social Change    
 Center for Social Dynamics & Complexity
 Arizona State University

 phone: 480-965-6213
 fax: 480-965-7671
 www: http://www.public.asu.edu/~cmbarton 

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