Markups distorted when zoom isn't constant along different axes

Development
1

Hi,

It is probably predictable that markups may work incorrectly with 3D view where zoom along different axes is different (in the animation Z-axis zoomed 8 times).
Does somebody know where to find methods that are responsible for this?
markups_with_inequal_zoom

5

I created a draft pull request but I need help to finilize it.

The idea:
As markups orientation is updated everytime camera is modified, the same way compensate scaling. Introduce vtkSmartPointer<vtkDoubleArray> GlyphScaleArray; and set this->GlyphMapper->SetScaleModeToScaleByVectorComponents();.
As orientation is updated in UpdateControlPointGlyphOrientation, I introduce UpdateControlPointGlyphScale function (in vtkSlicerMarkupsWidgetRepresentation3D.cxx).

The problem:
Camera scaling is in global coordinate system.
Markups points always oriented away from the camera: X-to the left, Y-up, Z-away from camera.
To compensate camera scaling I need to correctly project scaling from global coordinate system to markups point coord system (I don’t have enough knowledge what is quaternion and it seems I do that incorrectly).
markups_with_inequal_zoom_problem

6

To avoid parallel discussions, let’s talk about this in the pull request.

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