John, The 'unscale' operation computes the real value of that pixel.
-90.8230819702148 is the value stored at the pixel. -200.277178508775 is the value of the pixel. On Tue, Jul 26, 2011 at 5:35 AM, jt2000 <thak...@nexgenwireless.com> wrote: > Frank, > > Does the unscale option work as advertised? > > I have a raster with offset and scale set. > > Driver: GTiff/GeoTIFF > Files: raster.tif > raster.tif.aux.xml > Size is 10295, 7735 > Coordinate System is: > PROJCS["unnamed", > GEOGCS["unnamed", > DATUM["North_American_Datum_1983", > SPHEROID["GRS 80",6378137,298.257222101], > TOWGS84[0,0,0,-0,-0,-0,0]], > PRIMEM["Greenwich",0], > UNIT["degree",0.0174532925199433]], > PROJECTION["Transverse_Mercator"], > PARAMETER["latitude_of_origin",0], > PARAMETER["central_meridian",-87], > PARAMETER["scale_factor",0.9996], > PARAMETER["false_easting",500000], > PARAMETER["false_northing",0], > UNIT["Meter",1]] > Origin = (246885.000000000000000,4726455.000000000000000) > Pixel Size = (30.000000000000000,-30.000000000000000) > Image Structure Metadata: > INTERLEAVE=BAND > Corner Coordinates: > Upper Left ( 246885.000, 4726455.000) ( 90d 5'15.87"W, 42d38'56.20"N) > Lower Left ( 246885.000, 4494405.000) ( 89d59'22.95"W, 40d33'42.29"N) > Upper Right ( 555735.000, 4726455.000) ( 86d19'10.68"W, 42d41'18.81"N) > Lower Right ( 555735.000, 4494405.000) ( 86d20'28.58"W, 40d35'54.87"N) > Center ( 401310.000, 4610430.000) ( 88d11' 5.93"W, 41d38'22.21"N) > Band 1 Block=10295x1 Type=Float32, ColorInterp=Gray > * NoData Value=0 > Offset: -200, Scale:0.00305185094759972* > > > when I do a gdallocationinfo on it, i get the value of -90.82 as follows: > > gdallocationinfo -b 1 raster.tif 3000 3342 > Report: > Location: (3000P,3342L) > Band 1: > Value: -90.8230819702148 > Descaled Value: -200.277178508775 > > Applying unscale > gdal_translate -unscale -of GTiff ~/raster.tif raster2.tif > > gdallocationinfo -b 1 raster2.tif 3000 3342 > Report: > Location: (3000P,3342L) > Band 1: > Value: -200.27717590332 > > I would have expected -90.82 as the value. Am I wrong? > > -- > View this message in context: > http://osgeo-org.1803224.n2.nabble.com/gdal-translate-unscale-option-tp4237854p6620565.html > Sent from the GDAL - Dev mailing list archive at Nabble.com. > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev > -- Best regards, Chaitanya kumar CH. +91-9494447584 17.2416N 80.1426E
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