Hello,
I attached a 3159 x 1685 screen capture of a VTK canvas (in a Qt desktop program). I can resize it to whatever size I want, hence, whatever issue you’re having it is certainly not caused by VTK. Maybe the GUI system that creates the default window that backs vtkRenderWindow. Maybe that’s the resolution of your screen.
VTK_in_4K_display.zip (799.6 KB)
regards,
Paulo