[gdal-dev] Alpha band masking
Even Rouault
even.rouault at spatialys.com
Tue Nov 17 08:50:54 PST 2015
Le mardi 17 novembre 2015 10:19:59, Mutlu Ozdogan a écrit :
> Yes I have removed the xml file sorry I forgot to include that
Try also adding "-co alpha=no -overwrite" to the gdalwarp command line,
although it shouldn't have any influence on the pixel values at that stage.
>
> Sent from my iPhone
>
> > On Nov 17, 2015, at 3:04 AM, Even Rouault <even.rouault at spatialys.com>
> > wrote:
> >
> > Le mardi 17 novembre 2015 04:08:41, MUTLU OZDOGAN a écrit :
> >> Dear Even,
> >>
> >> The result of the gdalinfo -mm command is this:
> >>
> >> Driver: GTiff/GeoTIFF
> >> Files: pr026029_5m.tif
> >>
> >> pr026029_5m.tfw
> >>
> >> Size is 35921, 41035
> >> Coordinate System is:
> >> PROJCS["NAD83(HARN) / Wisconsin Transverse Mercator",
> >>
> >> GEOGCS["NAD83(HARN)",
> >>
> >> DATUM["NAD83_High_Accuracy_Reference_Network",
> >>
> >> SPHEROID["GRS 1980",6378137,298.2572221010002,
> >>
> >> AUTHORITY["EPSG","7019"]],
> >>
> >> AUTHORITY["EPSG","6152"]],
> >>
> >> PRIMEM["Greenwich",0],
> >> UNIT["degree",0.0174532925199433]],
> >>
> >> PROJECTION["Transverse_Mercator"],
> >> PARAMETER["latitude_of_origin",0],
> >> PARAMETER["central_meridian",-90],
> >> PARAMETER["scale_factor",0.9996],
> >> PARAMETER["false_easting",520000],
> >> PARAMETER["false_northing",-4480000],
> >> UNIT["metre",1,
> >>
> >> AUTHORITY["EPSG","9001"]]]
> >>
> >> Origin = (296789.742753763101064,562520.115095380693674)
> >> Pixel Size = (5.000000000000000,-5.000000000000000)
> >>
> >> Metadata:
> >> AREA_OR_POINT=Area
> >>
> >> Image Structure Metadata:
> >> INTERLEAVE=PIXEL
> >>
> >> Corner Coordinates:
> >> Upper Left ( 296789.743, 562520.115) ( 92d51'25.45"W, 45d30' 1.70"N)
> >> Lower Left ( 296789.743, 357345.115) ( 92d46' 5.00"W, 43d39'20.14"N)
> >> Upper Right ( 476394.743, 562520.115) ( 90d33'30.53"W, 45d32' 5.47"N)
> >> Lower Right ( 476394.743, 357345.115) ( 90d32'27.79"W, 43d41'16.23"N)
> >> Center ( 386592.243, 459932.615) ( 91d40'51.66"W, 44d36' 1.34"N)
> >> Band 1 Block=35921x1 Type=Byte, ColorInterp=Red
> >>
> >> Computed Min/Max=0.000,255.000
> >>
> >> Mask Flags: PER_DATASET ALPHA
> >>
> >> Band 2 Block=35921x1 Type=Byte, ColorInterp=Green
> >>
> >> Computed Min/Max=0.000,255.000
> >>
> >> Mask Flags: PER_DATASET ALPHA
> >>
> >> Band 3 Block=35921x1 Type=Byte, ColorInterp=Blue
> >>
> >> Computed Min/Max=0.000,255.000
> >>
> >> Mask Flags: PER_DATASET ALPHA
> >>
> >> Band 4 Block=35921x1 Type=Byte, ColorInterp=Alpha
> >>
> >> Computed Min/Max=0.000,255.000
> >>
> >> the exact commands I used are:
> >>
> >> gdal_translate pr026029_5m.tif tmp.tif -co alpha=no
> >
> > --> Did you remove tmp.tif.aux.xml as I mentionned before ?
> >
> > Note: given the use of gdalwarp you make, you could also just use
> > gdal_translate -projwin instead (caution: the order of arguments is not
> > the same since -projwin expect upper_left_x upper_left_y lower_right_x
> > lower_right_y)
> >
> >> then
> >>
> >> gdalwarp -te 422861.999 225313.018 489606.999 308903.018 -tr 5 5 tmp.tif
> >> out.tif
> >>
> >> The results of the out.tif is the problematic output as all the bands
> >> are zeros as in:
> >>
> >> Driver: GTiff/GeoTIFF
> >> Files: out.tif
> >> Size is 13349, 16718
> >> Coordinate System is:
> >> PROJCS["NAD83(HARN) / Wisconsin Transverse Mercator",
> >>
> >> GEOGCS["NAD83(HARN)",
> >>
> >> DATUM["NAD83_High_Accuracy_Reference_Network",
> >>
> >> SPHEROID["GRS 1980",6378137,298.2572221010002,
> >>
> >> AUTHORITY["EPSG","7019"]],
> >>
> >> AUTHORITY["EPSG","6152"]],
> >>
> >> PRIMEM["Greenwich",0],
> >> UNIT["degree",0.0174532925199433]],
> >>
> >> PROJECTION["Transverse_Mercator"],
> >> PARAMETER["latitude_of_origin",0],
> >> PARAMETER["central_meridian",-90],
> >> PARAMETER["scale_factor",0.9996],
> >> PARAMETER["false_easting",520000],
> >> PARAMETER["false_northing",-4480000],
> >> UNIT["metre",1,
> >>
> >> AUTHORITY["EPSG","9001"]]]
> >>
> >> Origin = (422861.999000000010710,308903.017999999981839)
> >> Pixel Size = (5.000000000000000,-5.000000000000000)
> >>
> >> Metadata:
> >> AREA_OR_POINT=Area
> >>
> >> Image Structure Metadata:
> >> INTERLEAVE=PIXEL
> >>
> >> Corner Coordinates:
> >> Upper Left ( 422861.999, 308903.018) ( 91d11'47.57"W, 43d14'48.02"N)
> >> Lower Left ( 422861.999, 225313.018) ( 91d10'55.54"W, 42d29'38.70"N)
> >> Upper Right ( 489606.999, 308903.018) ( 90d22'27.90"W, 43d15' 8.35"N)
> >> Lower Right ( 489606.999, 225313.018) ( 90d22'11.62"W, 42d29'58.50"N)
> >> Center ( 456234.499, 267108.018) ( 90d46'50.60"W, 42d52'26.06"N)
> >> Band 1 Block=13349x1 Type=Byte, ColorInterp=Red
> >>
> >> Computed Min/Max=0.000,0.000
> >>
> >> Mask Flags: PER_DATASET ALPHA
> >>
> >> Band 2 Block=13349x1 Type=Byte, ColorInterp=Green
> >>
> >> Computed Min/Max=0.000,0.000
> >>
> >> Mask Flags: PER_DATASET ALPHA
> >>
> >> Band 3 Block=13349x1 Type=Byte, ColorInterp=Blue
> >>
> >> Computed Min/Max=0.000,0.000
> >>
> >> Mask Flags: PER_DATASET ALPHA
> >>
> >> Band 4 Block=13349x1 Type=Byte, ColorInterp=Alpha
> >>
> >> Computed Min/Max=0.000,0.000
> >>
> >> Thank you so much.
> >>
> >> Mutlu..
> >>
> >>
> >>
> >> On Nov 16, 2015, at 3:21 AM, Even Rouault
> >> <even.rouault at spatialys.com<mailto:even.rouault at spatialys.com>> wrote:
> >>
> >> Le samedi 14 novembre 2015 22:26:48, Mutlu Ozdogan a écrit :
> >> Dear Evan
> >> Thank you so much for the input. I actually tried exactly those steps
> >> and unfortunately I still get 0s in the output file. Thank you again
> >>
> >> Could you post the result of "gdalinfo -mm your_input_file.tif" and the
> >> exact GDAL commands you use ?
> >>
> >> Mutlu
> >>
> >> Sent from my iPhone
> >>
> >> On Nov 14, 2015, at 1:00 PM, Even Rouault
> >> <even.rouault at spatialys.com<mailto:even.rouault at spatialys.com>> wrote:
> >>
> >> Le samedi 14 novembre 2015 19:49:02,
> >> ozdogan at wisc.edu<mailto:ozdogan at wisc.edu> a écrit : Dear All
> >> I have a 4-band air photo image in which the 4th band is the NIR band
> >> but it has also been designated as an alpha band. It is the geotiff
> >> format. For some reason whenever I reproject this file (using gdalwarp)
> >> or resize it (using gdal_translate) all four bands of the resulting
> >> files have zero values. It is as if the alpha band is being used to
> >> mask all band values. Any help reprojecting or windowing this large
> >> file without making while retaining all 4 band values would be much
> >> appreciated. Thank you
> >>
> >> Mutlu,
> >>
> >> The issue is probably indeed the NIR band being recognized as an alpha
> >> band. You can remove the alpha interpretation with :
> >>
> >> gdal_translate in.tif tmp.tif -co alpha=no
> >> rm tmp.tif.aux.xml (or del tmp.tif.aux.xml on Windows)
> >>
> >> The removal of tmp.tif.aux.xml is important otherwise the alpha
> >> interpretation would be kept in this XML file
> >>
> >> And then you can gdalwarp this tmp.file with the arguments you need :
> >>
> >> gdalwarp tmp.tif ...
> >>
> >> Even
> >>
> >> --
> >> Spatialys - Geospatial professional services
> >> http://www.spatialys.com
> >>
> >>
> >> --
> >> Mutlu Ozdogan, Ph.D.
> >> Associate Professor
> >> Department of Forest and Wildlife Ecology &
> >> Nelson Institute for Environmental Studies
> >> t: (608) 262-0873
> >> e: ozdogan at wisc.edu<mailto:ozdogan at wisc.edu>
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