[vtkusers] integrate variables filter in vtk

[Florian Bruckner]

hi, i would like to integrate sume functions of unstructed grid
variables (like the absolute value of magnetization vectors) over the
grid volume. In paraview this can be archieved by means of the
IntegrateVariables filter. 

Is there a vtk-specific way to do this? how could i access the volume of
individual tetrahedra (so that i could do the integration by hand)?

thanks
FloB