Inaccurate results from render_cam_view() on VTK versions 8.2+ about calcam HOT 6 CLOSED

This appears to be because of a change in behaviour of vtk.vtkRenderLargeImage(), when magnification is set > 1, from VTK 8.2 onward. I can't find any documentation that suggests this is an intentional change, or any way to work around it.

I've opened an issue about this against VTK: https://gitlab.kitware.com/vtk/vtk/-/issues/17964

from calcam.

I think there's a solution! Thanks to: http://vtk.1045678.n5.nabble.com/Offscreen-rendering-beyond-screen-resolution-with-WindowToImageFilter-magnification-td5724102.html . It looks like the answer is simply to use SetBorders(0) on the offscreen render window and then not use vtkRenderLargeImage at all.

from calcam.

Great! Does this mean the latest version of vtk is safe for Calcam now? (I'm about to request a python 3.9 distribution on freia with an appropriate version of vtk.)

from calcam.

Not the version on master yet, but very nearly...I'm working on it on a new branch called offscreen_render_dev. In a fever of optimism and ambition I took the approach of not just implementing the minimum laziest fix but trying to keep the code nice and clean at the same time....and now benchmarking that branch against master shows the wireframe alignment is coming out slightly different again, but I think that's a new bug which is a side-effect of what I've done.

I'm confident enough that the underlying problem is fixed that I'd say go ahead and request up-to-date VTK for the new python env, but if you want to hang on until I can confirm it's really fixed I'll try to look at it over the next couple of days.

from calcam.

Ok great, good to know. I'll go ahead and request the latest version then. Thanks Scott!

from calcam.

OK, as above - now merged on to master, the code on master tests OK for me on "old" VTK < 8.2 and also on VTK 9.0.1. I'm going to (finally) close this issue!

After I've delt with a few more issues I'll do a new release for this which will be Calcam 2.7 :)

from calcam.