V-Ray RT GPU 3.5 Review

This is a part of the article originally published on Dabarti site. For full article go here.

It has been over 7 months since the release of earlier Service Pack and we will be getting another free upgrade in Q1 of 2017. It’s now in public Beta stage. In this post I point out and review newest features and improvements of upcoming V-Ray RT GPU 3.5. I will focus only on GPU side of the engine as I think it deserves way more exposure than it gets. While it may seem like a small addition to V-Ray CPU (Adv) it’s in fact full-blown production rendering engine that paves the way for better and faster rendering workflow.

Over the course of last months I’ve been crazy enough to keep installing latest Nightly builds of V-Ray RT GPU on regular basis and abusing the hell out of it. As I’m sharing all the my testing data, bug reports and improvements ideas with Chaos Group team I also feel partly responsible for its current shape.

I. Adaptive Lights

First time I’ve got familiar with the concept of better multi-light rendering back in July 2016. At the time I was pointing out poor performance of many lights rendering and I got promised that it will get faster. Adaptive Lights took few months to develop and from what I know it’s quite innovative approach that yields very good results. I’m super happy about that feature as V-Ray RT 3.4 wasn’t effective with many lights and this improvement helps a lot. It did turn out better than expected as it not only made rendering faster for RT GPU, but also for V-Ray CPU Adv.

Pros:

• Speed improvement is very big. In some cases it render times dropped from 1 hour to few minutes. If you like data, here are my tests with some notes: Google Sheets.
• Lighting looks more accurate.
• Render elements like “Lighting” or “Global Illumination” look a bit different now, but much closer to what Adv is outputting.
• Works with both Brute Force and Light Cache as secondary GI engine.
• It looks very cool with BF+BF when it optimizes the settings and switches to Adaptive Lights:

Cons:

• This doesn’t affect the VRayLightMtl which is still a bit sluggish. It’s better to use mesh lights instead.

Usage:

Based on my tests so far it always performs better with Adaptive Lights turned on. It’s also turned on by default so there is no reason to switch it on when you use “fresh” settings. In case you need to change it for some reason. In 3ds Max you can use it from Production Renderer settings under Global Switches rollout. You may to change settings type “Advanced” or “Expert” if it’s invisible.

II. Aerial Perspective

Pros:

• Super fast.
• Easy way of adding realistic Aerial Perspective without the need of doing it at compositing.
• V-Ray sky and sun system is closely connected with Aerial Perspective settings. For example, low visibility will also block some of the sun intensity.

Cons:

• It’s still not perfect for all cases, as it won’t generate volumetric rays (god rays, etc.).

Usage:

• In 3ds Max it’s available under the Environment -> Atmosphere as Effect you can add it at any time.
• I would recommend using it for basically all outdoor big scale environments.
• It’s useful to add VRayAtmosphere Render Element if some adjustments are needed.
• Best used with Affect environment rays turned on.

Example of using aerial perspective for underwater shot. Effect setup starts at 2:50.

III. Procedural Shading

I just love procedural shading, but I’ve missed some things for procedural bump. Around 2 Months ago I compiled a list of things that didn’t work as expected and sent it to Chaos Group, after few weeks most of the issues were gone and I’ve produced this series of cool looking shaders:

Pros:

• You can create very complex bump maps using composite, mix, gradient, output and noise maps. You have pass everything trough VRayColor2Bump.
• Mapped gradient ramp works now very well and can help with creating diffuse color maps from grayscale bump maps.
• It is sampled quite effectively so it doesn’t slow the rendering heavily when compared with bitmap based bump maps.
• Procedural 3D maps use very little memory and don’t need UV mapping.

Cons:

• There is no good way of mixing VRayColor2Bump with VRayNormalMap. With so many good normal bump maps available it’s a must have for more complex shading.
• Usage of VRayColor2Bump isn’t very obvious for new users. While this map works great inside bump slot of VRayMtl it doesn’t work inside VRayBumpMtl or as additional bump slot of VRayNormalMap.
• There are limits to number of maps you can use on GPU. For example you can use only 6 layers of composite. You can worked around that by using composite inside composite.
• More complex procedural noises are missing. Any kind of Worley noise would be most welcome, even simple Cellular would do for most shaders. Bercon maps would be perfect. But I would love to have unified V-Ray procedural noise map that would work across all 3D packages.

Usage:

• Everywhere. You can use procedural techniques to enhance your shaders in so many ways that it would be hard to write about all of them.
• Mix procedural noise with tile-able bitmaps to make it look more random.

For some ideas how to create this kind of shading, check the video below:

Want to know more? Read the rest of the article on Dabarti site!