Fiducial markers hidden when cropping ROI disabled, and shown when cropping ROI enabled

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1

I created a fiducial maker that was located just outside a cropping ROI.

  • When cropping ROI is enabled and displayed, the external fiducial marker isn’t shown (this is logical).
  • When cropping ROI is enabled but not displayed, the external fiducial marker is shown (this is not logical).
  • When cropping ROI is not enabled and not displayed, the external fiducial marker is shown (this is logical).
  • When cropping ROI is not enabled but is displayed, the external fiducial marker isn’t shown (this is not logical).

This occurs in version 4.13.0-2022-01-19 of Slicer.
Display of the 3D volume is tied to enabling of the cropping ROI, not display of the cropping ROI (that is logical).

—DIV

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2

Sorry, I have mischaracterised the problem.
It is not due to external location of the marker. When the marker is far outside, it can be seen always.
Rather, it seems to be due to unfortunate conflict between the marker and the light-grey handles at the corners of the cropping ROI, or (similarly) the coloured handles in the centre of the faces of the cropping ROI.
So, it’s still unexpected/undesirable behaviour, although the actual behaviour/mechanism is different to how I initially interpreted it.
—DIV

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3

Markups control point labels are only displayed for visible points. Visibility is determined only for the centerpoint position, not for the entire point glyph, therefore, as you noted, a line can occlude a point. It would be computationally too expensive to check visibility of all (or many) points of a glyph, so it is not likely that we will change this behavior.

If you must always see the labels then you can enable Occluded visibility (in Markups module → Display → Advanced → 3D display section).

4

Thanks. Actually, I didn’t notice the ROI box line occluding the markups, only the ‘handles’ on the ROI box.

As you guessed, retaining the label would be sufficient to avoid the main cause of confusion for me.