Integration over quad cells should be more accurate
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
Currently, integration over a quad cell is done in vtkIntegrateAttributes.cxx, which cuts a quad to two triangles along a diagonal, integrate over each triangle and returns the sum. The result is not very accurate.
One better algorithm is suggested by Samuel Key (see attached file).
Edited by Mathieu Westphal (Kitware)