No scale on vol ren scalar opacity mapping
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
For unstructured volume rendering, it is important to have a scale parameter for the opacity mapping that defines what a unit length with respect to the opacity value means with respect to the model. ParaView 2 had this parameter, but it is missing in ParaView 3.
To see the need for the parameter, first create a wavelet source, convert it to an unstructured grid (filter it with Clean to Grid) and volume render it. The result will be an appropriately fuzzy image. Now run that through the transform filter to scale each dimension by 100. Volume render the result and it will look very opaque. This is because the opacity is now accumulating 100x as much as before the scaling.