[gdal-dev] Save min/max values in TIFF

[Even Rouault]

Le 11/11/2022 à 19:12, Javier Jimenez Shaw a écrit :
> Hi
>
> I am creating a GeoTIFF file with C++. It is a large DSM (one band of 
> Float32). Because I am generating it, I already know the min and max 
> values.
> I would like to store the min and max values directly in the TIFF, not 
> in a sidecar file. Is there any gdal metadata (stored in the TIFF) 
> that can be used? That way, when I open it in QGIS, the range of the 
> band will be accurate.

yep, see https://gdal.org/user/raster_data_model.html#raster-band

Demo:

$ python
from osgeo import gdal
ds = gdal.GetDriverByName('GTiff').Create('test.tif', 1, 1)
ds.GetRasterBand(1).SetMetadataItem('STATISTICS_MINIMUM', '0')
ds.GetRasterBand(1).SetMetadataItem('STATISTICS_MAXIMUM', '1')
ds.GetRasterBand(1).SetMetadataItem('STATISTICS_MEAN', '2')
ds.GetRasterBand(1).SetMetadataItem('STATISTICS_STDDEV', '3')


$ gdalinfo test.tif
Driver: GTiff/GeoTIFF
Files: test.tif
Size is 1, 1
Image Structure Metadata:
   INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (    0.0,    0.0)
Lower Left  (    0.0,    1.0)
Upper Right (    1.0,    0.0)
Lower Right (    1.0,    1.0)
Center      (    0.5,    0.5)
Band 1 Block=1x1 Type=Byte, ColorInterp=Gray
   Min=0.000 Max=1.000
   Minimum=0.000, Maximum=1.000, Mean=2.000, StdDev=3.000
   Metadata:
     STATISTICS_MAXIMUM=1
     STATISTICS_MEAN=2
     STATISTICS_MINIMUM=0
     STATISTICS_STDDEV=3

$ tiffdump -m 1000 test.tif
test.tif:
Magic: 0x4949 <little-endian> Version: 0x2a <ClassicTIFF>
Directory 0: offset 8 (0x8) next 0 (0)
ImageWidth (256) SHORT (3) 1<1>
ImageLength (257) SHORT (3) 1<1>
BitsPerSample (258) SHORT (3) 1<8>
Compression (259) SHORT (3) 1<1>
Photometric (262) SHORT (3) 1<1>
StripOffsets (273) LONG (4) 1<402>
SamplesPerPixel (277) SHORT (3) 1<1>
RowsPerStrip (278) SHORT (3) 1<1>
StripByteCounts (279) LONG (4) 1<1>
PlanarConfig (284) SHORT (3) 1<1>
SampleFormat (339) SHORT (3) 1<1>
42112 (0xa480) ASCII (2) 244<<GDALMetadata>\n  <Item 
name="STATISTICS_MAXIMUM" sample="0">1</Item>\n  <Item 
name="STATISTICS_MEAN" sample="0">2</Item>\n  <Item 
name="STATISTICS_MINIMUM" sample="0">0</Item>\n  <Item 
name="STATISTICS_STDDEV" sample="0">3</Item>\n</GDALMetadata>\n\0>

Even

>
> Thanks.
> .___ ._ ..._ .. . ._. .___ .. __ . _. . __..  ... .... ._ .__
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> hay infinitos pensamientos irracionales.
>
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