RT Question and a matter of cards

[padre.ayuso]

Hi there,

This question may be answered somewhere else and if someone knows the thread and can direct me, great. Otherwise, here we go:

I currently have two GTX970. I saw that I can render a scene in RT while working on my next scene, on my same computer, which is quite nice. However, my workstation is up for an upgrade. Say I want to go the RT route and get myself two Titan X and a computer that can handle these I'd be able to go through my scenes like lightening speed. However, say I'm processing RT on my computer and I'm working on another scene and it is time to light my second scene. With two Titan X I'm dedicating one card per scene. One to render, one to work on. However, I know that when I'm rendering and both my cards are taken, I can barely move around my scene. Suppose I take my current GTX970 and add it to my new computer with the two Titans, would I be able to dedicate the 970 to run anything else other than rendering while my two Titans are both rendering? Thus, I expect to remove the problem of not being able to move on the scene while using RT in Active Shade View on my second scene.

Hope that made sense.

[yavor.rubenov]

Hello,

In V-Ray 3.30 we've added option to pick which GPUs to use for rendering:



that way you can have only one GPU rendering from the current Max session.
A few things to note:

• You should be using In-Process RT for this to work. (It is possible to do it with out of process but requires some more configuration).
• The setting for the active GPU is saved in a global environment variable when Max closes - so the last Max you close will overwrite the settings from the other ones. So you should check it the next time you start Max.
• Rendering on the GPU requires CPU (host) RAM as well.

Best regards,
Yavor

[padre.ayuso]

Hello,
[*]You should be using In-Process RT for this to work. (It is possible to do it with out of process but requires some more configuration).

Thanks Yavor. I think that answers the question I had. Now, what is In Process RT and what do you mean by out of process?

[yavor.rubenov]

Again something we've added in 3.30

In-Process RT means that the RT Engine runs inside the 3ds Max process - there is no separate V-Ray console that starts when rendering as was the case in 3.20. When In-Process the RT engine can share some data with Max (leading to somewhat less memory required) and also can transfer the resulting data a bit faster.

Out of process RT is the way RT ran in 3.20 and before - the rendering happened in a separate process.
There is a checkbox in the RT settings that controls that - default is In-Process RT engine.

[padre.ayuso]

Thanks Yavor, that makes sense and yes, I use 3.3 so I guess I'm using the In Box settings.

So I have pretty much decided I'm not getting a motherboard that supports the 3 Graphics Cards that I mentioned, I'd need to get one that supports 4 GPUs of this size and the jump is quite high, so I'll pass this time, perhaps on my next upgrade.

But tell me again Yavor, what do I do, in the case I have a scene rendering in the background in RT and I'm using one GPU and I'm using the other GPU to work on my second scene and I need to light and I don't want to be all sluggish and be able to move on my second scene Active Shade View while lighting?

[yavor.rubenov]

If you want to use the display GPU for rendering you should lower the "Rays per pixel" and/or the "Ray bundle size parameters" (http://docs.chaosgroup.com/display/V...useV-RayRTGPU?)

[padre.ayuso]

Thanks Yavor. Will take this into account when I get the new rigs.

[savage309]

Also you can check our FAQ http://docs.chaosgroup.com/display/V...X/V-Ray+RT+FAQ. It is pretty short and my save you some time .