Why use V-Ray RT GPU?
Even though there is a more limited subset of implemented features for V-Ray RT GPU it doesn't mean that it's useless. It's possible to get much faster results rendering on the GPU compared to the CPU. Graphics cards are improving at a much quicker rate than CPUs and they are set to continue to do so. Graphics cards can also more easily be stacked to deliver even more power to your fingertips. V-Ray is also increasing the compatible features with every release, so it's only a matter of time before everything is supported.
Graphics cards are improving year on year with some very exciting developments in the pipeline of the major players.
What GPU should I get?
Tough question! If money is not an issue than something like the Titan X might be interesting for you. It's got 12GB of memory and would serve you incredibly well. AMD also has the Radeon R9 290X which should serve you just as well. If money is a little tighter but you're still serious about rendering on the GPU then NVIDIA is bringing out the GTX 980 Ti. This will be released at a more reasonable price point than the Titan X, but it only packs 6GB of memory. As with all these things, it comes down to money and your preference between NVIDIA and AMD, or other providers.
The NVIDIA Titan X is an exciting development in the world of computer graphics cards. Image courtesy of NVIDIA
Trace and GI Depths
Let's move onto some of the settings that V-Ray gives us to control our RT rendering. Firstly, we have a couple of settings that let us control the depth of trace and GI. According to V-Ray the trace depth ‘represents the maximum number of bounces that will be computer for reflections and refractions'. The GI depth on the other hand specifies ‘the number of bounces for indirect illumination'. Obviously the higher these numbers are the longer the render will take to calculate because more rays have to be calculated.
Being able to adjust the number of bounces that happen inside of the engine enables us to much more easily control how long our renders take
Ray bundle size and Rays per pixel
According to V-Ray ‘This controls the number of rays that are sent to the V-Ray RT render servers for processing.' It's not recommended to increase this beyond 512 and please remember that this is not the exact amount of rays, but proportional to it. The important thing here is in reference to distributed rendering. The smaller the number the more times that the client will need to communicate with the server. This could slow the rendering down. This is the same principal as with bucket sizes and distributed rendering.
Having control over these settings helps us manage how often our client machines communicate with server machines in a distributed context
V-Ray helpfully gives us the ability to control some of the features that are rendering when using V-Ray RT. These controls enable us to avoid rendering things like displacement and motion blur if we want to get a quicker result. Simple tick the check boxes for the features that you want to be rendered.
This shows the implemented features that can be turned on and off based on your particular needs
New Skin Shader
V-Ray 3.0 not only includes a new VRaySkinMtl shader with multi-layered subsurface scattering and reflections but you can also render the VRayFastSSS2 using VRay RT. Even the more complex and less-used features are becoming available in real-time, and this is a big plus. The sub surface scattering (SSS) material is brilliant, partly because it's fast (obviously, the name gives that away) but also because there are a set of presets which you can use as a starting point. There is even a ketchup preset! Utilize this material for skin, wax, marble and other similar materials.
The help section of the V-Ray website is really helpful for drilling down to what specific settings do
To wrap it up
I would highly recommend exploring the world of GPU rendering because it gives you an added dimension of flexibility when you are working through iterations of materials, lighting, and camera angles. And if your graphics card is super-powerful then you may find that you're able to utilize it on production renders. Some of the settings can seem a bit daunting but once you get your head around them, it's not all that scary.
Pro tip: Graphics card with multi memory slots
The next generation of graphics cards by both AMD and NVIDIA are likely to be able to stack memory on top of each other. This is a game-changer as it'll allow for access to an incredible amount of memory all on one card. It looks like NVIDIA will do this with a card codenamed Pascal, likely to be released in 2016.
Pro tip: Other GPU renderers
The last few years have seen a rapid expansion of GPU renderers hitting the market including Octane
, Furry Ball
. Free trials will help you explore which one is right for you.
Furry Ball wins the prize for the best named GPU renderer!
V-Ray 3.0: New Features - Faster Rendering
V-Ray 3.0: New Features: Interface and Frame Buffer
Download a V-Ray 3.0 free trial
V-Ray RT Supported Features
3ds Max Projects from 3dtotal