You can now preview mental ray rendering interactively in 3dsMax: camera navigation, adjustments to light and material parameters, and object creation are immediately reflected in the ActiveShade window using mental ray. The rendering provides an accurate look overtime – just as what you will get in the final frame.
mental ray takes advantage of the ActiveShade improvements that are released with 3dsMax 2015: Many changes are captured more frequently offering finer grain updates. These changes include: viewport navigation, switching between viewports, adjustments to light parameters, and certain other scene changes (Creating, moving, or deleting objects).
Pascal
[vimeo 94391571 w=800 h=600]
Inside mental ray 
It seems to crash a lot for me after a few minutes, and I have to force kill it and restart.
Any word about future developments? This would be more interesting.
We are sorry to hear about these issues. Unfortunately we have already identified few problems with Max 2015 Active Shade rendering but it could help if you could log the issues.
ActiveShade has its own limitations which impact usability and interactivity within 3ds Max.
Regarding future developments of mental ray, we plan to further improve (reduce) response time of progressive rendering when interactively manipulating the scene.
And of course, using modern lighting techniques and materials (based on BSDF known to the renderer) will help speed up progressive rendering going forward.
Thanks, Pascal, it’s nice to hear the plans you have for future development! One question, where would you like it logged, with AD, or on the Nvidia forum? Many thanks.
Better to log through Autodesk, thanks.
Thank you for sharing your info. I truly appreciate your efforts and I am waiting for your next write ups
thanks once again.