[FWTools] Gdaltranslate ESRI grid to GeoTIFF: pixel values are blown up.

Frans Knibbe frans at geodan.nl
Mon Oct 2 04:49:32 EDT 2006


I am trying to prepare elevation grids for display and query with the 
UMN MapServer. The source data are ESRI floating point grids. As I 
understand geoTIFF to be a good format to use with MapServer I use 
gdaltranslate (from FWTools 1.0.5) to convert the grids to geoTIFFs. The 
problem is that in the resulting geoTIFF images the pixel values are 
somehow blown up. Gdalinfo does not report the minimum and maximum 
values of the GeoTIFFs, but opening a file in ArcMAP reveals the minimum 
value to be 1.17E-38 and the maximum value to be 3.4E38, when the 
original values were -6.96 and 30.5.

When I use ArcMap to convert the grids to TIFF, the pixel values do seem 
correct, but somehow those TIFFs are not drawn by MapServer. MapServer 
does draw the files made by gldaltranslate. Can anyone help me with 
getting the pixel values right?


Frans Knibbe,

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