Min/Max values of raster changed after converting to COG about rio-cogeo HOT 7 CLOSED

Is there any way I can modify the band overviews without breaking COG?

no, you need to do a full re-write of the COG!

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Hi @hnagrath09,
Can you share the command you use to create the COG ?

could you also confirm that pixel values are the same within QGIS or share the files.

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IIRC, QGIS uses overviews to compute min and max, so the values shown are approximate. I would suggest you read the full raster in rasterio and compute the min and max by hand to see if they really are different.

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@hnagrath09 is the issue solved ?

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Hi @hnagrath09,
Can you share the command you use to create the COG ?

could you also confirm that pixel values are the same within QGIS or share the files.

Hi Vincent,

I am simply using
rio cogeo create <input> <output>

I have checked with one more DSM. It also shares the same problem. Also, the value tool is giving different values for both raw and COG tif. I haven't checked with rasterio yet. It may be due to the reason mentioned by @dionhaefner because values are more precise at greater zoom levels.

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because values are more precise at greater zoom levels.

so there is no real bug, QGIS uses overview to get data values, feel free to re-open @hnagrath09

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Hi @vincentsarago. I need to update the COG file to have same min/max overviews as the original raster. But using either GDAL or RasterIO as below breaks COG.

With RasterIO:

orig = rasterio.open('original_dsm.tif')
cog = rasterio.open('cog_dsm.tif', 'r+')

cog.update_tags(1, **orig.tags(1))
cog.close()

With GDAL:

orig = gdal.Open('original_dsm.tif')
cog = gdal.Open('cog_dsm.tif', gdal.GA_Update)

orig_band1 = orig.GetRasterBand(1)
cog_band1 = cog.GetRasterBand(1)
stats = orig_band1.GetStatistics(True, True)

cb1.SetStatistics(stats[0], stats[1], stats[2], stats[3])
cog = None

Is there any way I can modify the band overviews without breaking COG?

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