I am attempting to create an underwater scene in order to assess the effect of water caustics upon tracking ability of objects. The scene comprises, from an overhead camera, a complex rock base, a patterned hemipshere and noisy waves that are all contained within a cyclindrical test area. I have produced caustics before (using an online tutorial) using an iray renderer, but find that, although I manage to get good water caustics, the quality and user-friendliness of everything else is lost completely (jpeg attached). Hence, I change tact and reproduced the same environment with the mental ray renderer. However, I now find that, although the user-friendliness and quality is impeccable, I am completely unable to visualise the water caustic effect (jpeg number 2)! I am very new to 3DS Max so would appreciate any help that can source my issue for producing caustics with mental ray!