[GRASSLIST:2039] Re: MrSID conversion

[Markus Neteler]

On Thu, Dec 11, 2003 at 06:42:26PM -0500, Christopher Fonnesbeck wrote:
> Does anyone happen to know of a good conversion utility for MrSID files 
> so that I can import some ortho photos into GRASS? I found one called 
> mrsiddecode, but it doesnt use the projection information in the header 
> file, making it virtually useless.

There is hope: gdal_translate.

Example: Spearfish aerial images in MrSID format, e.g. from
http://data.geocomm.com/catalog/US/61050/326/group129-3.html
Spearfish, SD (44103d7)
Deadwood South, SD (44103c6)

mrsiddecode -tif -input i44103d7_a.sid -output i44103d7_a.tif 
gdalinfo i44103d7_a.tif
#[reports what you have seen, missing coordinate system]

#Assigning a Spatial Reference System (a_srs) to fix the missing raster map
#projection info (UTM/NAD83), get info from MrSID header file:

#check EPSG file: /usr/local/share/proj/epsg for EPSG code:
gdal_translate -of GTIFF -a_srs '+init=epsg:26913' \
               i44103d7_a.tif i44103d7_a_NAD83.tif

gdalinfo i44103d7_a_NAD83.tif
#reports NAD83 now, file fixed.

#Reprojecting maps ("warping") to different projection/geodetic datum
#(UTM/NAD27) to make ready for Spearfish location import:

gdalwarp -t_srs '+init=epsg:26713' i44103d7_a_NAD83.tif \
                 i44103d7_a_NAD27.tif

gdalinfo i44103d7_a_NAD27.tif

#in Spearfish sample dataset
r.in.gdal in=i44103d7_a_NAD27.tif out=i44103d7

I recommend to use GDAL from CVS.
Hope this helps,

 Markus

-- 
Markus Neteler     <neteler at itc.it>       http://mpa.itc.it
ITC-irst -  Centro per la Ricerca Scientifica e Tecnologica
MPBA - Predictive Models for Biol. & Environ. Data Analysis
Via Sommarive, 18        -       38050 Povo (Trento), Italy