Rendering speed slower than "raw" Vtk

Hello, I am loading a CT volume 600x600x312 to slicer4, and playing with the same volume in raw VTK by using a modified Medical4 demo where I use VtkOpenGLGpuMapper (I guess it’s the same I get in slicer4 when I select Vtk GPU raycast), gradient opacity, same colormap as in the slicer4 test, shading disabled in both cases, so all in all should be the same settings.

Question 1: is there a way to share the settings exactly between slicer4 and a VTK c++ program?
Question 2: Slicer4 is way slower in rendering compared to a bare VTK render window. It’s slower during interaction, almost as if Slicer4 is always rendering full quality, and it’s much slower also in the final renders. Am I missing some settings, or is Slicer4 doing something different than VTK?


Rendering speed should be exactly the same as in any other VTK-based application.

There might have been a couple of weeks when the 4.11.x preview version always rendered in full quality. Try latest preview version and tune quality settings in Volume rendering module / Advanced / Techniques / Quality and Interactive speed.

I don’t know if it is related or not, but I always have been getting poor rendering performance when the quality is set to adaptive, and had better performance with ‘Normal’ quality.