Hello,

I am following up on my previous post hoping to get some advise on the use of **segmentation effects** programmatically.

I am currently running a smoothing operation (gaussian), two subtractions, and an additional smoothing (median). This is the section of my code that calls the effects;

```
# Define master volume using the geometries within the segmentation... This is needed for the implementation of any effect!
masterVolumeNode = segNode.GetNodeReference(segNode.GetReferenceImageGeometryReferenceRole()) #----> if there is a failure point, it is here!
# According to the 3D Slicer documentation, this is the most appropriate way of implementing the effects, using the widget calls
segmentEditorWidget = slicer.qMRMLSegmentEditorWidget()
segmentEditorNode = slicer.vtkMRMLSegmentEditorNode()
slicer.mrmlScene.AddNode(segmentEditorNode)
segmentEditorWidget.setMRMLSegmentEditorNode(segmentEditorNode)
segmentEditorWidget.setSegmentationNode(segNode)
segmentEditorWidget.setMasterVolumeNode(masterVolumeNode)
segmentEditorWidget.setMRMLScene(slicer.mrmlScene)
segmentEditorWidget.setSegmentationNode(segNode)
inputSegmentIDs = vtk.vtkStringArray()
segNode.GetDisplayNode().GetVisibleSegmentIDs(inputSegmentIDs)
segmentEditorNode.SetOverwriteMode( slicer.vtkMRMLSegmentEditorNode.OverwriteNone )
# Essentially, the index for the segments is given by the order in which the segments were created or imported
# Only visible segments are read, but visibility is set to True by default, so all of the segments will be read
#
# Now we apply the effects on each segment...
# ...Firts, we run a median filter operation on the splint!
splintSegmentID = inputSegmentIDs.GetValue(0)
segmentEditorWidget.setCurrentSegmentID(splintSegmentID)
segmentEditorWidget.setActiveEffectByName("Smoothing")
effect = segmentEditorWidget.activeEffect()
effect.setParameter("SmoothingMethod","GAUSSIAN")
effect.setParameter("KernelSizeMm",str(1.0))
effect.setParameter("ApplyToAllVisibleSegments",str(1))
effect.self().onApply()
# ...After applying the filter, we subtract both the maxilla and the mandible sequentially
maxillaSegmentID = inputSegmentIDs.GetValue(1)
mandibleSegmentID = inputSegmentIDs.GetValue(2)
segmentEditorWidget.setCurrentSegmentID(splintSegmentID)
segmentEditorWidget.setActiveEffectByName("Logical operators")
effect = segmentEditorWidget.activeEffect()
effect.setParameter("Operation", "SUBTRACT")
effect.setParameter("ModifierSegmentID", maxillaSegmentID)
effect.self().onApply()
# ...subtract mandible
segmentEditorWidget.setCurrentSegmentID(splintSegmentID)
segmentEditorWidget.setActiveEffectByName("Logical operators")
effect = segmentEditorWidget.activeEffect()
effect.setParameter("Operation", "SUBTRACT")
effect.setParameter("ModifierSegmentID", mandibleSegmentID)
effect.self().onApply()
# ...finally, one additional smoothing operation
splintSegmentID = inputSegmentIDs.GetValue(0)
segmentEditorWidget.setCurrentSegmentID(splintSegmentID)
segmentEditorWidget.setActiveEffectByName("Smoothing")
effect = segmentEditorWidget.activeEffect()
effect.setParameter("SmoothingMethod","MEDIAN")
effect.setParameter("KernelSizeMm",str(0.5))
effect.setParameter("ApplyToAllVisibleSegments",str(1))
effect.self().onApply()
```

When I run this sequence, the splint segment (green) seems to converge towards the edges of the volume at the front and the sides. If I am not mistaken, this happens when a gaussian or median filter is applied near the end of the master volume. **If this is the case, how do I avoid this?**