On Thu, Jun 14, 2018 at 10:55 PM, Even Rouault <even.roua...@spatialys.com> wrote: > > > > Wanna take a crack at implementing this ? > > > > Too many API changes required, starting with GDALGetRasterStatistics(), > > GDALComputeRasterStatistics() and all else following. There must be an > > easier solution. But thanks for your offer:-) > > We don't necessary need to change the API. The function could just set the > metadata item, and the client would read it with GDALGetMetadataItem()
Thinking about it, I do not want to support approximate statistics, therefore something like STATISTICS_VALID_RATIO does not work for me, only something like STATISTICS_N_VALID which requires exact statistics. Approximate statistics are confusing for users, unless it is made clear that these statistics are approximations. E.g. a user calculates exact statistics with some software other than GDAL and then wonders why results are different between gdalinfo and that some software known to calculate exact statistics. > > > Enhancement request: set STATISTICS_APPROXIMATE=UNKNOWN if it is unknown. I > > checked with some externally provided sample data and GDAL 2.3.0 does not > > report STATISTICS_APPROXIMATE. > > I didn't want to pollute statistics with STATISTICS_APPROXIMATE=NO when exact > computation has been done. So basically you have STATISTICS_APPROXIMATE=YES or > no STATISTICS_APPROXIMATE at all when exact computation has been done (which > is the normal assumption) Looking at random samples, the normal assumption must be STATISTICS_APPROXIMATE=YES if STATISTICS_APPROXIMATE is not set. IMHO, GDAL should set STATISTICS_APPROXIMATE=YES unless GDAL itself has computed exact statistics. If in doubt set STATISTICS_APPROXIMATE=YES. I am aware it's a conflict between providing results quickly to users and providing exact results to users which might take longer to get. I am for exact results. Markus
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