[vtkusers] vtkFixedPointVolumeRayCastMapper related help

[Alark Joshi]

Hello,

I have three volumes that are all located in the same space and I would like to see regions where they overlap and so on. 

On trying to using raycastMapper/texture2d/texture3d, I found that the last vtkVolume that I added to the renderer always dominated the visualization. Basically, if I order the volumes as 

ren->AddVolume(v1);
ren->AddVolume(v2);
ren->AddVolume(v3);

then volume v3, dominates the visualizations and occludes everything behind it. I tried this with the "nut.slc" and "bolt.slc" too, in my earlier attempts. Then I found  "vtkFixedPointVolumeRayCastMapper" that allows, as per the specification "intermixing with geometric data". 

I was able to get one volume and one actor (in the example of the nut and bolt), to work perfectly. But, it does not work as well with my real world data, since I need the actor to be translucent. As soon as I change the opacity of the actor, the volume again dominates the visualization and the 3-dimensionality is lost. 

Ideally, I would like to be able to render all these 3 volumes and I have a feeling that vtkFixedPointVolumeRayCastMapper has the answer and I may not be using it properly. The class specification mentions "It works with all input data types and up to four components." 

Please let me know if anyone has any suggestions/ideas. Thanks. 

Regards,

Alark