You have three options, you can use all, but the first one is the most important:
- crop your input volume to the region of interest & resample to have sufficiently high resolution using the
Crop volumemodule: specify your ROI, selectIsotropic spacing, select sufficiently lowspacing scalevalue (the lower the value, the more details you can preserve during segmentation, but more memory and processing time you will need; typically 0.5 … 0.2 should work), select bspline interpolator - smooth the labelmap representation using
Smoothingeffect in Segment editor module - smooth the generated surface: in Segment editor module, click on the small arrow on the “Show 3D” button, choose
Set surface smoothing, and increase the smoothing value. (in older Slicer versions, this setting was only available in Segmentations module: clickUpdatebutton in the row ofClosed surfacerepresentation inRepresentationssection, click onBinary labelmap -> Closed surfacerule, increaseSmoothing factorvalue)