On Thu, Oct 11, 2012 at 6:50 PM, Frank Warmerdam <[email protected]> wrote: > Radim, > > I gather the problem is that GDAL cannot tell whether saved statistics in > metadata are exact or not, right?
It should be possible, at least .aux.html has <Approximate>1</Approximate>. In any case, if it is not sure that cached stats are exact, it should return CE_Warning if bApproxOK=false and bForce=false, I think. > I don't have any real plan to resolve > this unfortunately. I ticket might be prudent. https://trac.osgeo.org/gdal/ticket/4857 Radim > Best regards, > Frank > > On Thu, Oct 11, 2012 at 8:39 AM, Radim Blazek <[email protected]> > wrote: >> >> GDALGetRasterStatistics API doc: >> "Returns the minimum, maximum, mean and standard deviation of all >> pixel values in this band. If approximate statistics are sufficient, >> the bApproxOK flag can be set to true in which case overviews, or a >> subset of image tiles may be used in computing the statistics. >> If bForce is FALSE results will only be returned if it can be done >> quickly (ie. without scanning the data). If bForce is FALSE and >> results cannot be returned efficiently, the method will return >> CE_Warning but no warning will have been issued. This is a >> non-standard use of the CE_Warning return value to indicate "nothing >> done"." >> >> >> My understanding is that if it is called with bApproxOK=false and >> bForce=false and exact statistics (from all raster pixels) are not >> available/cached, it should return CE_Warning. Instead, it is giving >> estimated (from sample) cached statistics and it returns CE_None. >> >> Is it expected? If it is, how can I test if exact statistics (from all >> raster pixels) are available/cached (to avoid >> GDALComputeRasterStatistics() if not necessary). Also, the meaning of >> both params should be probably better described in doc. >> >> Radim >> _______________________________________________ >> gdal-dev mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/gdal-dev > > > > > -- > ---------------------------------------+-------------------------------------- > I set the clouds in motion - turn up | Frank Warmerdam, > [email protected] > light and sound - activate the windows | http://pobox.com/~warmerdam > and watch the world go round - Rush | Geospatial Software Developer > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
