Raster quantile: increase sample size

Fixes #35465 (part two)
qgis · Apr 19, 2020 · ebdb546 · ebdb546
1 parent 970149f
commit ebdb546
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Showing 2 changed files with 9 additions and 5 deletions.
diff --git a/src/core/raster/qgscolorrampshader.cpp b/src/core/raster/qgscolorrampshader.cpp
@@ -204,11 +204,12 @@ void QgsColorRampShader::classifyColorRamp( const int classes, const int band, c
     {
       // Quantile
       if ( band < 0 || !input )
-        return; // quantile classificationr requires a valid band, minMaxOrigin, and input
+        return; // quantile classification requires a valid band, minMaxOrigin, and input
 
       double cut1 = std::numeric_limits<double>::quiet_NaN();
       double cut2 = std::numeric_limits<double>::quiet_NaN();
-      const int sampleSize = 250000;
+      // Note: the sample size in other parts of QGIS appears to be 25000, it is ten times here.
+      const int sampleSize = 250000 * 10;
 
       // set min and max from histogram, used later to calculate number of decimals to display
       input->cumulativeCut( band, 0.0, 1.0, min, max, extent, sampleSize );

diff --git a/src/core/raster/qgsrasterinterface.cpp b/src/core/raster/qgsrasterinterface.cpp
@@ -352,16 +352,19 @@ void QgsRasterInterface::initHistogram( QgsRasterHistogram &histogram,
       // Because it is easier to define fixed lower value for the chart, we calc optimum binCount
       // for higher resolution (to avoid calculating that where histogram() is used. In any any case,
       // it does not make sense to use more than width*height;
-      myBinCount = std::min( 2000, histogram.width * histogram.height );
 
       // for Int16/Int32 make sure bin count <= actual range, because there is no sense in having
       // bins at fractional values
       if ( !mInput && (
              mySrcDataType == Qgis::Int16 || mySrcDataType == Qgis::Int32 ||
              mySrcDataType == Qgis::UInt16 || mySrcDataType == Qgis::UInt32 ) )
       {
-        if ( myBinCount > histogram.maximum - histogram.minimum + 1 )
-          myBinCount = int( std::ceil( histogram.maximum - histogram.minimum + 1 ) );
+        myBinCount = std::min( histogram.width * histogram.height, static_cast<int>( std::ceil( histogram.maximum - histogram.minimum + 1 ) ) );
+      }
+      else
+      {
+        // This is for not integer types:
+        myBinCount = std::min( 2000, histogram.width * histogram.height );
       }
     }
   }