Fix for shifted values in interpolation plugin

mhugent · mhugent · commit a994d5531b08 · 2009-10-06T18:36:44.000Z
git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@11759 c8812cc2-4d05-0410-92ff-de0c093fc19c
diff --git a/src/analysis/interpolation/qgsgridfilewriter.cpp b/src/analysis/interpolation/qgsgridfilewriter.cpp
@@ -55,7 +55,7 @@ int QgsGridFileWriter::writeFile( bool showProgressDialog )
   outStream.setRealNumberPrecision( 8 );
   writeHeader( outStream );
 
-  double currentYValue = mInterpolationExtent.yMaximum();
+  double currentYValue = mInterpolationExtent.yMaximum() - mCellSizeY / 2.0; //calculate value in the center of the cell
   double currentXValue;
   double interpolatedValue;
 
@@ -68,7 +68,7 @@ int QgsGridFileWriter::writeFile( bool showProgressDialog )
 
   for ( int i = 0; i < mNumRows; ++i )
   {
-    currentXValue = mInterpolationExtent.xMinimum();
+    currentXValue = mInterpolationExtent.xMinimum() + mCellSizeX / 2.0; //calculate value in the center of the cell
     for ( int j = 0; j < mNumColumns; ++j )
     {
       if ( mInterpolator->interpolatePoint( currentXValue, currentYValue, interpolatedValue ) == 0 )

Original file line number	Diff line number	Diff line change
`@@ -55,7 +55,7 @@ int QgsGridFileWriter::writeFile( bool showProgressDialog )`
`55`	`55`	`outStream.setRealNumberPrecision( 8 );`
`56`	`56`	`writeHeader( outStream );`
`57`	`57`
`58`		`- double currentYValue = mInterpolationExtent.yMaximum();`
	`58`	`+ double currentYValue = mInterpolationExtent.yMaximum() - mCellSizeY / 2.0; //calculate value in the center of the cell`
`59`	`59`	`double currentXValue;`
`60`	`60`	`double interpolatedValue;`
`61`	`61`
`@@ -68,7 +68,7 @@ int QgsGridFileWriter::writeFile( bool showProgressDialog )`
`68`	`68`
`69`	`69`	`for ( int i = 0; i < mNumRows; ++i )`
`70`	`70`	`{`
`71`		`- currentXValue = mInterpolationExtent.xMinimum();`
	`71`	`+ currentXValue = mInterpolationExtent.xMinimum() + mCellSizeX / 2.0; //calculate value in the center of the cell`
`72`	`72`	`for ( int j = 0; j < mNumColumns; ++j )`
`73`	`73`	`{`
`74`	`74`	`if ( mInterpolator->interpolatePoint( currentXValue, currentYValue, interpolatedValue ) == 0 )`