[Gdal-dev] Importing ESRI .hdr Labelled raster via r.in.gdaldisplays strange aliasing pattern

[Patton, Eric]

I've figured this one out...I had to use r.in.bin, and explicitly declare the extents, null value, number of bytes, rows, and columns for each input flt file.

Sorry for clogging the bandwidth.

~ Eric.


-----Original Message-----
From: gdal-dev-bounces at lists.maptools.org on behalf of Patton, Eric
Sent: Fri 5/11/2007 2:35 PM
To: gdal-dev at lists.maptools.org
Cc: grassuser at grass.itc.it
Subject: [Gdal-dev] Importing ESRI .hdr Labelled raster via r.in.gdaldisplays strange aliasing pattern 
 
I'm importing an Arc Floating-point raster using the 'EHdr/ESRI .hdr Labelled' driver in gdal:

$ gdalinfo 45_04_N_66_44_W_BATHY.flt

Driver: EHdr/ESRI .hdr Labelled
Size is 2641, 3721
Coordinate System is `'
Origin = (2481609.500000000000000,7340725.500000000000000)
Pixel Size = (1.000000000000000,-1.000000000000000)
Corner Coordinates:
Upper Left  ( 2481609.500, 7340725.500) 
Lower Left  ( 2481609.500, 7337004.500) 
Upper Right ( 2484250.500, 7340725.500) 
Lower Right ( 2484250.500, 7337004.500) 
Center      ( 2482930.000, 7338865.000) 
Band 1 Block=2641x1 Type=Byte, ColorInterp=Undefined
  NoData Value=-99999.999

The projection is New Brunswick Double Stereographic (EPSG #2953). I have set up a Location with these projection parameters.
Th import seems to progress fine with no errors, but the imported raster doesn't display any data, just a jagged, greyscale grid. (A screenshot of the imported raster was too big to attach, but I can provide it in a separate email attachment if anyone is interested.)  

I suspect, but am not sure, that I need to use gdal_translate instead and pass some CREATOPT parameters? 

Also noteworthy is the fact that I had to do a tiny hack to the hdr file as per Frank Warmerdam's suggestion through the GDAL bugtracker:
(Background: I was received a malloc error when trying to import the ESRI Floating-point raster. See http://trac.osgeo.org/gdal/ticket/1573)

>From Frank Warmerdam:

"The problem is related to initialization when the NBITS keyword is missing
from the .hdr file.  In 1.4.0 a bunch of new code was introduced for NBITS
< 8, but it also added a dependency on having the keyword present.

The workaround is to add "NBITS 8" in the .hdr file.

Fix is to default to 8 in the code.  The fix has been committed in trunk,
and 1.4 branch and it should be released in 1.4.2."


I have added the above fix to the hdr file prior to using r.in.gdal to import the raster.

Any help appreciated!


~ Eric.

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