Downstream Effects of Changing SegmentEditorWidget Source Volume

Development
, , ,
1

Hello,

I would love some help understanding the effect changing the source volume has on the SegmentEditorWidget. I recently ran into an issue where, after changing the source volume with setSourceVolumeNode(), the Threshold effect didn’t update its default MaximumThreshold parameter to the maximum voxel intensity of the new volume. I know that I could identify the new maximum intensity and set it programmatically, but I wondered if there was a method by which I could make sure all default parameters similar to MaximumThreshold would update as soon as I changed the source volume. I’ve seen the sourceVolumeNodeChanged() function pop up in a couple places in the documentation, but I don’t really know how that might factor into this.

For context, here’s a bit of my code:

Initially Defining the SegmentEditorWidget

## Define master volume node
masterVolumeNode = slicer.mrmlScene.GetFirstNodeByClass("vtkMRMLScalarVolumeNode")

## Create segmentation
segmentation = slicer.mrmlScene.AddNewNodeByClass("vtkMRMLSegmentationNode")
segmentation.CreateDefaultDisplayNodes()
segmentation.SetReferenceImageGeometryParameterFromVolumeNode(masterVolumeNode)

# Prepare to edit the segment
segmentEditorWidget = slicer.qMRMLSegmentEditorWidget()
segmentEditorWidget.setMRMLScene(slicer.mrmlScene)
segmentEditorNode = slicer.mrmlScene.AddNewNodeByClass("vtkMRMLSegmentEditorNode")
                                                      
segmentEditorWidget.setMRMLSegmentEditorNode(segmentEditorNode)
segmentEditorWidget.setSegmentationNode(segmentation)
segmentEditorWidget.setSourceVolumeNode(masterVolumeNode)

Later, I create a new volume with the exact same features as the masterVolumeNode except that I’ve squared (or otherwise transformed) its voxel intensities.

Setting the New Source Volume

newSourceVolume = slicer.mrmlScene.GetFirstNodeByName(newVolumeName)
segmentEditorWidget.setSourceVolumeNode(newSourceVolume)

Then, I check the MaximumThreshold parameter:

Checking MaximumThreshold

segmentEditorWidget.setActiveEffectByName("Threshold")
effect = segmentEditorWidget.activeEffect()
effect.parameter("MaximumThreshold")

But it ends up being the old maximum intensity.

Any help understanding if I could add something after setting the new volume that would cause the MaximumThreshold parameter to update on its own would be very much appreciated.

Thanks!