Scene with only reflection and refraction. Any way to speed up render times?

[MikkoK]

Hello

I have made few scenes with only a glass vase and few lights. It is completely black scene and the shape of the vase comes from reflections and refractions. The result looks totally awesome, but I was thinking is there any way to speed up the render times? With Vray RT one full hd frame takes from 1 min 30 secs to few minutes and that's a bit too much to render totally about 10 000 frames. Do you people have any recommendations what I should do to speed up renderings or is there anything to do? I've tried denoiser, but I need to separate the lights to their own elements and denoiser does not denoise those LightSelect elements. There's a link to one of the scenes below if you would like to check it up.

Thank you for any tips!!

Mikko

[Svetlozar Draganov]

Try to increase Max. Noise value a bit and notice the change in the render times versus quality.
This is the main parameter that controls the balance between both, if you would like to cut render times increasing it will help but be careful since it will also affect the quality of the image.
You may try to increase it to 0.01 and if the quality is too poor try something in between of 0.01 - 0.005, if quality is still fine you may try values above 0.01.

[MikkoK]

I was hoping there are some other parameters to change because there are not any diffuse or shadows to render. Only reflections and refractions. Even Max. Noise value 0.01 gives a bit too noisy results. I tried to render the same scene with Scanline renderer and with only the reflections it takes only 2 seconds to render. I was hoping the refractions with Vray RT wouldn't take minutes to render.

[MikkoK]

By the way. Is there any way to use denoise to different render elements? I have this LightSelect render elements for all the lights and I would like to use denoise for those. Is it somehow possible?

[Svetlozar Draganov]

I was hoping there are some other parameters to change because there are not any diffuse or shadows to render. Only reflections and refractions. Even Max. Noise value 0.01 gives a bit too noisy results. I tried to render the same scene with Scanline renderer and with only the reflections it takes only 2 seconds to render. I was hoping the refractions with Vray RT wouldn't take minutes to render.

V-Ray is very well optimized under the hood to calculate only properties that are visible in the final rendering, if diffuse or shadows are not it won't spend much time on those but focus on what's visible and noisy.
Max Noise (and Max Time and Max Paths) is the main parameter to control the render speed, if the noise after certain value becomes too much just backup a step or two and this would be the best render time for the quality.

V-Ray Denoiser is another tool that could be used to speed up the rendering. Instead of clearing all the noise during the rendering you may leave some fine noise and clear that with the denoiser.

Comparing Scanline vs V-Ray is a whole new topic. I'm sure that Scanline could render that scene for 2 seconds but proper comparison means to compare the quality of the image as well and I doubt that Scanline produce image quality similar to V-Ray.

[Svetlozar Draganov]

By the way. Is there any way to use denoise to different render elements? I have this LightSelect render elements for all the lights and I would like to use denoise for those. Is it somehow possible?

It's not possible in 3dsMax but it is possible to do that with Standalone Denoiser tool which comes with the installation.
It's also preferable to use that tool when denoising animation frames since it has an option to take into account not only the frame being denoise but also its neighbor frames which give better results.

V-Ray Denoiser tool in Nuke also allows to denoising render elements separately.