Hi Radim, thx for explain. Your explanation of extimated strategy could explain why the extimated is more precise rather than the actual strategy. I guess are the null values to produce a wrong "actual" results.
Can you say me in which file I can found the code for the extimate and actual strategy to verify my hypotesis.? Thx. 2015-08-12 11:22 GMT+02:00 Radim Blazek <[email protected]>: > On Tue, Aug 11, 2015 at 3:09 PM, Andrea Peri <[email protected]> wrote: >> Hi, >> trying the rendering of a raster floating point using the cumulative count >> cut. >> I see it is quite good if I set the values 2.0,100.0% (not 98%) and >> use the accuracy at value "estimate". >> Instead always with the same values for cumulative count cut, but >> using the accuracy "actual". >> The result is really poor. The image became totally black with only >> few isles of grey. >> >> This is a surprise for me because the accuracy "actual" take a long >> time and the name seem to say more precision. >> >> I like to know what is the strategy used for actual: estimate and the >> strategy for accuracy: actual. > > Actual takes all pixels, estimate takes 250000 pixels (whole data > extent with resolution giving approximately 250000 pixels). Some > providers may use different approach to get estimated values, e.g. > GDAL provider may use approximated values returned by GDAL, IIRC. > > Radim > > >> >> Many thx. >> >> -- >> ----------------- >> Andrea Peri >> . . . . . . . . . >> qwerty àèìòù >> ----------------- >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user -- ----------------- Andrea Peri . . . . . . . . . qwerty àèìòù ----------------- _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user
