Volume quality worsens when pressing mouse down and rotating


I’m rendering some volume in my application. I noticed a phenomenon of volume quality inconsistency with and without holding down mouse button.

Without pressing down the button:

With pressing down the button, it becomes dimmer:

And the detail flashes when rotating the volume:

This is the stable volume rendering people want to see using some very old OpenGL:

Initially I guessed that it might have to with the ‘desired update rate’, so I increased the value through vtkRenderWindowInteractor::SetDesiredUpdateRate(), but it became even worse. I’m developing a application for people in my institute to inspect mouse neuron 3D volumes and these volumes often present very dense and busy neuronal structures. Such an instability in the volume rendering quality makes people’s eyes hurt to look at it for a long time. It’s very much appreciated if anyone can guide me how to remove this condition.

Thanks very much,