Shifting problem in model slice display

[alientex (Tex)]

Hi,

I created a segment and exported it into a model. When I turn on slice display visibility, I notice an extreme contour shift, as shown in the images below.

Why is this happening?

[cpinter (Csaba Pinter)]

The labelmap consists of 3D boxes, and compared to that the surface is a continuous representation. I think simply the slice position you look at is not at the center of the labelmap voxel. Btw I wouldn’t call a half voxel discrepancy extreme. It’s similar to the partial volume effect.

[MJamal (SamS)]

I am also facing this problem. In my case, it varies from system to system. I tried checking on another system, but I didn’t see the same effect (or shifting issue) there.

Is it system-dependent?

[lassoan (Andras Lasso)]

Please use the latest version of Slicer, we have managed to reduce the effect of smoothing causing slight shift.

If you have problems with accuracy (some details not accurately preserved) you can always work on a smaller region of interest and increase the resolution of the binary labelmap representation of the segmentation.

[MJamal (SamS)]

@lassoan

Please use the latest version of Slicer, we have managed to reduce the effect of smoothing causing slight shift.

Could you please share the commit link for these changes? I’d like to take a look at it.

@lassoan

tpu can always work on a smaller region of interest

Sorry, I didn’t quite understand—what is tpu?

[lassoan (Andras Lasso)]

@MJamal

Could you please share the commit link for these changes? I’d like to take a look at it.

I had to make this fix at VTK level. See all the details here:

Slight offset in vtkWindowedSincPolyDataFilter if normalization is enabled

@MJamal

Sorry, I didn’t quite understand

You can reduce the ROI and increase the resolution as described here. “Specify geometry” function is described here.