Slow paint speed with large (10GB) volume

I have a colleague with a fairly large micro-CT scan (10GB), and he is experiencing sluggish response times when painting with a sphere brush in the 2D slices (Show 3D not enabled). His machine is windows with 128GB RAM. Not sure on specs for the CPU.

Seems to me this is a pretty large volume, and it’s just a lot of data to go through for painting with intensity range turned on? Any suggestions? I’m thinking the best way to proceed is probably to chop it into a few pieces and work on it in sections.

Any ideas would be most appreciated - thanks!!


This volume is about 30-50x larger than average volumes, which exposes performance bottlenecks that we normally don’t perceive at all. A 0.5s operation may turn into a 20s operation.

Potential solutions:

  • crop and/or downsample: as you suggested, to work with smaller pieces at a time
  • use larger hardware: if it’s just a one-off case then you can try to rent a very powerful computer from a cloud provider and see if it makes the workflow fast enough
  • optimize performance: build Slicer in “release with debug info” mode and do the segmentation with a profiler attached; if you identify the performance bottlenecks then we can give advice about how to improve the update speed