scene size and limitation . Experience feedback please

[fraggle]

Dear Vray user,

We would like to introduced live GPU preview rendering during client meeting to gain time on the decision path (artistic part). Camera angle, lighting, material & color are endless and we expect GPU preview to save us a lot of time .

We work only on houses interior scene, still image, and we have the folowing process in mind :
- Live preview on GPU
- Production on CPU (with pass etc...)

Now several questions arise :
- Scene size: what kind of interiro scene can fit on 4Gb of ram? can you post your GPU rendering of interior scene witht he amount of ram available on your computer)
Do you advice to work with 2 differents texture resolution and different poly model (low vs high) from preview to prod to be able to fit the scene into the GPU ram (means twice the work!)
- light/shader : What can't be done in GPU that can be done on the CPU. Is there a comparaison chart beetween the 2 system somewhere?
- Any other issues we should be aware of?

Better to ask your feedback before investing in a couple of GPU.
Thanks for your help.

PS : As per octane user, their is not GPU ram limitation on octane as it used the Vram intead of the GPU ram.On their forum it is advice to have 5 time the amount of Vram than the amount of GPU. Gpu with 4 GB ram will request 20 Gb of ram. Why should Vray be limited by the GPU Ram and not octane? Something to do with code?

[Alan Iglesias]

Although I do not have a 4GB card (only 3GB), I will at least try to give you something to work with. Hopefully others will chime in.

Your GPU preview ideas sound very good, and in fact I have been doing some of this myself. Clients are definitely digging the real-time feedback as we look at different colors, textures, camera angles, etc.

• As I mentioned, I am working with 3GB cards, so I cannot be completely precise here for your situation. Buit I can tell you that GPU RAM needed is less than what Max reports after a normal rendering. How much lower? Hard to say exactly but I am currently rendering a scene (1.75 million faces) that Max reports takes 4.5GB to render. The GPU does it using only 765MB, clamping texture resolutions at 512 (which is currently the default).

• It should be noted that texture maps can be a big part of your RAM usage, but luckily with RT you can quickly keep map resolutions down to save RAM compared to CPU-based, high-resolution renders. And at display resolutions things tend to look pretty good even with lower-res maps. If someone out there with a 4GB card could max it out and see what Max reports, it would be a big help. Hopefully you'll be able to get the most important parts of your scene into GPU RAM for previews without actually making lower-resolution versions of your models!

• Most of the things that RT/GPU cannot do yet have to do with pre-render set-up operations like procedural maps and topographical displacements. It's looking like many of these things are being worked on as we speak. It well may be quite easy to substitute bump maps and bitmaps for your preview materials until RT/GPU supports all of these things. There is no chart that I know of, but there is some information here: http://www.spot3d.com/vray/help/rt10...d_features.htm

The best thing you can do now is grab at least one 4GB board and do some testing with your files! Things are changing rapidly and people are very excited about the possiblities of GPU rendering so any experience now will be of great help in the future.. Even if you find you cannot use it for complete, comprehensive previews yet, you could at least use the card to quickly preview basic materials, lighting, exposure, camera composition, etc., etc., likely speeding up your workflow considerably.

I hope you have fun,

-Alan

[fraggle]

Thanks for this very detailled feedback.
As per the link http://www.spot3d.com/vray/help/rt10...d_features.htm, can someone from Chaos group upated it or make a chart and keep it up to date. That will be very helpfull.
For example, there is not information regarding vray plane and or Vray Portal light in the link but I find out on this forum that such light are not working properly.

Thanks

[fraggle]

Thanks for this very detailled feedback.
As per the link http://www.spot3d.com/vray/help/rt10...d_features.htm, can someone from Chaos group upated it or make a chart and keep it up to date. That will be very helpfull.
For example, there is not information regarding vray plane and or Vray Portal light in the link but I find out on this forum that such light are not working properly.

Thanks

What about vraysoftbox, or hdri or texture light. Is it working?

[vlado]

I believe that they are working in the latest builds, yes. HDRI and texture lights for sure.

Best regards,
Vlado

[tricky]

These are questions that we too are starting to ask. I have just started a thread (before reading this one!) that asks similar things.

We are involved with interior scenes, and I am wondering if we should invest more heavily in RT. I need to check out exactly what is/is not supported I think. Are bumps not supported in RT GPU? I will have a read...

[mario74]

for usage of memory i want to jump in here:

i have here a model that get rendered at interior and exterior scenes, depending on interior up to 20 mio Polys, while MAX takes around 18 GB for rendering, i never run out of the 4 GB i have on my GTX 680.

once loaded (loading bitmaps takes the most time, even if they are stored local) - changing color or update the bitmap on some material works well and fast.

i use 2.40.03 and latest driver from nvidia here. it only happend once since update to 2.40.03 while changing a material, RT quitted work and i had to restart MAX.

cause of missing render-elements, i dont use RT for production.

[tricky]

What is the deal with RT GPU and render elements? Is it likely to be implemented in the near future? Is it even possible?

I wonder if a simple 'hack' way could be implemented by the development team in the meantime, maybe some presets for each of the main render elements where there is a sort of global material overide to simulate RawReflection, VrayLighting etc?

[vlado]

What is the deal with RT GPU and render elements? Is it likely to be implemented in the near future? Is it even possible?

This is actually mostly done and working in our internal builds... still needs a bit of polish though.

Best regards,
Vlado

[tricky]

This is actually mostly done and working in our internal builds... still needs a bit of polish though.

Best regards,
Vlado

That's good to know. Any kind of ETA? We are just about to start a new project and I am thicking of taking the bull by the horns and using RT GPU entirely. Initially we will start with our existing machines (GTX670) but if all goes well, we will upgrade to dual titans (or similar).

[mario74]

multi-subobject dont come out well in RT (looks like too much bump), but for interiors you may need the include/exclude list of lights much more often.

anyway, with the render-elements we will give a try also for production.

[3LP]

Yeah the render elements are definitely one of the main reason why we are still not switching to RT for production render (in addition to the maps/scripts maps/etc no supported that are still blocking the migration).
A ETA would be great

Stan

[Guest]

Render elements and excluded lights are the big ones for me.

[tashko.zashev]

Hi all,

Render elements support for the RT engine is a complex but major upgrade on the RT functionality.
It's hard to say a specific release date at this stage, but the work is in progress.