Gaussian smoothing to reduce staircase artifact

[mlavik1]

The volumes have quite obvious staircase artifacts:

See a discussion about this topic here: https://discourse.slicer.org/t/volume-rendering-staircase-artifacts/14666

Maybe we can reduce this artifact by smoothing the volume dataset a bit.

Even using a naive box filter I managed to reduce the artifact a bit:

[SnowWindSaveYou]

i think use the cubic sampling also a good way to solve this problem.... one main reason of staircase result is that dataset is not 1:1:1. in this case if we sampling dataset as its ratio, we would get a better result. （ but impact efficiency due to more sampling count)

for example a dataset has 5mm slice thickness

use cubic sampling for raycast ( this result not use cubic sampling for gradient )

[mlavik1]

Thanks a lot for the suggestion! That's a good idea. I did a really quick test, and it really does improve the visuals quite a lot. Before:

After:

I'll add a separate task for this, and see if I can push something soon. I will keep this task open, since it would be nice to have an optional setting for gaussian smoothing as well (as a cheaper alternative, for performance constrained platforms). Thank you!

[SnowWindSaveYou]

did you analysed what kind of filter is suitable for it? i tried to add a bilateral filter for smoothing in my fork, but i'm not sure is this a suitable filter to smoothing it. i use bilateral filter is because of i want to save its displayed edge after smoothing, but it still got a lot impact, maybe i need to change to other filter or carefully adjust parameters.

[mlavik1]

Hi again! Sorry, recently I've been occupied with so many other things so I haven't had the opportunity to experiment with this yet, but I should probably try to prioritise it soon. I'm not sure what filter would be best for this, though I was thinking of experimenting with the filters offered by SimpleITK (which you can use form Slicer 3D I think?) first, to get some experience with them.