timothyhanson

Vray training series... http://www.max-depth.com

Have you tried "Clamp max ray intensity"? also you can leave your other settings the same and try just increasing the samples in your refraction which are very low at a value of 8 from what you posted in the other forum. Try 32 in your refraction.

If you are having ram issues, try using tiled exr's and converting your geo to proxies. These two techniques alone will improve memory usage, and decrease render times by 10 to 30% on average.

RT is only meant for preview purposes for near-realtime look dev. By default it first undersamples the scene so that it may give you instant feedback giving a very grainy image, and then continues to refine with pass after pass ultimately leading to a clean image much like the "Progressive" image sampler option in your render globals. http://www.max-depth.com

Francisco is correct, refraction by it's very nature needs something to refract for you to see its values. Your second image is refracting the ground which is clearly visible beneath the glass, but in your first image it is refracting the black void behind. If you think about it, unless there is a color value to the fog parameter of the refraction all any glass or water material has to use for it to be visible is what it can reflect or refract from the environment around it.

Since the release of Vray 3 you really don't need to use light caching hacks anymore. Go brute force / brute force for everything because it is fast enough to handle it. Not only will you never have flickering in your animations, but it is a smoother render. Give that a try, and also look into clamping max ray intensity to 20 in your global advanced options.

Perhaps the OP doesn't know how the physical cam works in that the default f-stop of 8 would take a dimly lit scene and make it seem black to someone that doesn't know how to expose an image with a real camera. Set the f-stop to 1, if it doesn't illuminate the scene then the problem is not the physical cam. Process of elimination.

Vray 3.1 for Maya: Advanced Production Workflow and Techniques is an in depth training series from VFX Supervisor Timothy Hanson with over 5 hours of advanced training covering major topics such as... Vray Frame Buffer Settings Global Options Image Sampler Render elements RT Engine Vray Proxy (creation and export) Vray Volume Grid (opendVDB) Object Property Nodes Vray Fur Vray Displacement Lighting (Dome, Area, Point, IES, Sun, Mesh-light) Shaders (Standard MTL, Blend, SSS, Light Material, MTL Wrapper) Physical Camera