Is RT worth pursuing for high end interior CGIs?

[tricky]

We have a number of projects at the moment that are calling for high quality photorealistic renders. They are interiors of high-end apartments. Lots of furniture. Lots of lights. Lots of polygons. Candles. Curtains...you know the sort of thing...

We have reasonably fast workstations and a small render farm. They are based around i7 processors with 16GB RAM. The graphics cards are mid-end geforce cards in the workstations. However, we are finding that performing distributed renders (using standard Vray) are taking a while, particularly during the 'test-render' phase (Applying textures and rendering regions. Adding geometry and rendering regions. Adding lights and rendering regions...). With the number of images we are producing, I am looking at ways to significantly speed up production.

We have always struggled to get off the ground with RT, chiefly because some of the plugins we use aren't supported (Bercon and Multitexture for example). However, I would consider changing our workflow so that we use only methods that are supported by RT if I knew that RT would speed things up for us.

I have seen a number of threads and pictures with machines with more than 1 GFX card in them - often 3 or 4 (or more!!!). I am wondering if it would be worth spending the time and money building one of these 'rigs'. Is anybody seriously using RT for production renders?

This is the type of thing I am talking about.



We do a lot of post production 'painting' using various render elements.

(I guess one of the reasons for my concern of investing in RT is that most/all demos using RT have been for simple scenes, such as a car. They look great, but a straightforward car with a couple of lights, a couple of shaders and a vraysun is not as complex as an interior scene with many lights and lots of bouncing GI)

[Alan Iglesias]

Tricky, if you can possibly afford it I would suggest you go ahead and grab a 6GB Titan and do some testing with your typical files. Render them to your noise level satisfaction and do some simple math regarding what the times would be with more GPUs. Unless you are comparing Fermis to Keplers, they seem to scale in a very linear manner. Further, you will be able to see how much RAM your typical file will take to render on the GPU which will give you more valuable information regarding rendering with RT/GPU in your future.

Even if you do not decide to go with rendering on the GPU for final work right now, you will still have an excellent board for quickly designing materials and lighting that you can add to the GPU fray in the future, and you only spent around 1000$US.

Alternately, I do have a friend who just installed 2x 6GB Titans in his workstation. If you could ftp me one of your typical files perhaps we could do some test renders for you and let you know render times per noise level, RAM usage, etc. We would have to make sure the file is GPU compatible of course so if we do this, we could talk a bit about how we could go about doing that.

Best,

-Alan

[Morbid Angel]

There is a couple of things to consider here. If you browse the forum one of the biggest problems in my opinion is the drivers. Nvidia comes out with drivers as often as you take out your trash! and I read that this causes stability issues of all kinds. Also my latest understanding is that the render elements are not supported by the cpu or the gpu to date (vlado can correct me here of course). Then there are obvious things like, shaders do look different in some cases dramatically between cpu/rt cpu/rt gpu versions, so I read that if you start a project strictly in gpu you should stay there, going back to regular vray would cause different results, something you may not like during production. Then there is obvious stability issues since its such a new product and new drivers all the time, create unstable environment, I guarantee you often crashes and whatever else (vlado can correct me here too if this is incorrect) my experience is based on several not so modern cards, including quadro 4000 and geforce 580.

As for texture/procedural workflows, you can of course use regular texturing methods, but it may create more work for you...and if you sum things up from above, it may just be as slow as your regular work methods...Of course as I posted in another thread, few years from now this will be a totally different story...but we must wait!

[tricky]

Tricky, if you can possibly afford it I would suggest you go ahead and grab a 6GB Titan and do some testing with your typical files. Render them to your noise level satisfaction and do some simple math regarding what the times would be with more GPUs. Unless you are comparing Fermis to Keplers, they seem to scale in a very linear manner. Further, you will be able to see how much RAM your typical file will take to render on the GPU which will give you more valuable information regarding rendering with RT/GPU in your future.

Even if you do not decide to go with rendering on the GPU for final work right now, you will still have an excellent board for quickly designing materials and lighting that you can add to the GPU fray in the future, and you only spent around 1000$US.

Alternately, I do have a friend who just installed 2x 6GB Titans in his workstation. If you could ftp me one of your typical files perhaps we could do some test renders for you and let you know render times per noise level, RAM usage, etc. We would have to make sure the file is GPU compatible of course so if we do this, we could talk a bit about how we could go about doing that.

Best,

-Alan

That is a very kind offer. I will need to work out the logistics of this. I am certain some of the things we are using are not compatible with RT GPU.

[tricky]

There is a couple of things to consider here. If you browse the forum one of the biggest problems in my opinion is the drivers. Nvidia comes out with drivers as often as you take out your trash! and I read that this causes stability issues of all kinds. Also my latest understanding is that the render elements are not supported by the cpu or the gpu to date (vlado can correct me here of course). Then there are obvious things like, shaders do look different in some cases dramatically between cpu/rt cpu/rt gpu versions, so I read that if you start a project strictly in gpu you should stay there, going back to regular vray would cause different results, something you may not like during production. Then there is obvious stability issues since its such a new product and new drivers all the time, create unstable environment, I guarantee you often crashes and whatever else (vlado can correct me here too if this is incorrect) my experience is based on several not so modern cards, including quadro 4000 and geforce 580.

As for texture/procedural workflows, you can of course use regular texturing methods, but it may create more work for you...and if you sum things up from above, it may just be as slow as your regular work methods...Of course as I posted in another thread, few years from now this will be a totally different story...but we must wait!

These are all fair and valid points. The thing is, I could sit on the fence forever and not risk anything. There will be some things that work and some that don't. We get crashes quite regularly even now! I guess I just need to know if RT is worthwhile for interior scenes and not just damn cars!!!!

Are there differences between RT GPU, RT CPU and straightforward Vray Vlado? Because of our need for elements, I still think we will be doing the main renders overnight across our renderfarm, but we would want RT GPU to be used during material/lighting setup. If they are significantly different, this isn't going to work.

[alexyork]

One of the things I noticed that doesn't work in RT compared to normal VRay is environment and GI overrides. We use these a LOT so we can have custom images or gradient maps for the skylight override but use a high res photo for the environment, with yet another different map for reflection/refraction. Quite a common setup for photomontages. I hope this will make it over to RT soon because it's a bit of a deal-breaker for me at the moment.

The other thing is that when rendering with GPU I get a great deal of system hangs and it's not very responsive - a bit like things used to be with Mental Ray back in day, actually!

[tricky]

Thanks for these points Alex.

Most of the interiors we work with include some/all of the following:-

Vray2sided materials - do these work with RT GPU?
Bercon tile textures, with or without multitexture - I guess we would need to 'bake out' a large texture if RT GPU doesn't support this soon
Bump maps - does RT GPU support these - we sometimes use normal maps in the bump slot
Vray lights that include and exclude certain objects - almost a 'fill' light
Vray lights that are invisible to reflections

[Neilg]

Great for material & model work, not so good for final scenes in my experience. If all of the furniture is bespoke and you're modeling from photographs you'd use it a lot there. Also for initial lighting setups when it's an empty grey box. (or lighting changes, when you temporarily delete everything high poly to quickly throw together a dusk version)

[Morbid Angel]

I think the biggest problem of them all is that not enough people use RT in production, so there isn't a strong demand to develop it further faster (of course what do I know ) maybe Im wrong, but this is my impression. I'd say that nothing wrong with getting a single Titan and giving it a go, be sure to send Chaos lots of feedback on things...and see them improved who knows...maybe soon it will be possible!

[Alan Iglesias]

That is a very kind offer. I will need to work out the logistics of this. I am certain some of the things we are using are not compatible with RT GPU.

Yes, there would probably be a bit of "massaging" to be done and perhaps a work-around or two. But I have done it on a few files already, so I'm kinda used to it. I wouldn't mind taking the time because I'm as curious as anyone as to how RT/GPU will stack up with other folks' pro scenes.

Personally, I have been building scenes from the get-go for GPU for a year now. Most of my stuff lately has been fairly straightforward product visualization, so it has been pretty easy for me to do that. But with the 6GB to work with now, I would love to see if it might be time for more folks to get into it, or at least to check it out.

It is true that interior shots with a lot of light bouncing around is a substantially bigger challenge for RT/GPU (or any GI renderer) than the simple sun/sky/auto scenario and it can take some time to get the noise level to where it is acceptable, but how long this will take with the current hardware is what we want to find out, right?

Indeed, I will be doing some interiors myself in the coming weeks so it will be interesting to see whether or not I deliver them rendered in GPU or not.

Let me know if you want to go ahead; PM me and we'll get it going. It might take a bit of time, but hey, we are talking about our possible future here...and some of the best innovations in the world are worked out when folks work together as a team.

Best,

-Alan

[Alan Iglesias]

Vray2sided materials - do these work with RT GPU?
Bercon tile textures, with or without multitexture - I guess we would need to 'bake out' a large texture if RT GPU doesn't support this soon
Bump maps - does RT GPU support these - we sometimes use normal maps in the bump slot
Vray lights that include and exclude certain objects - almost a 'fill' light
Vray lights that are invisible to reflections

I'll give a few of these a shot, Tricky...

Yes, two-sided materials are working. Vlado was saying that if they get too complex then there could be a problem but I haven't run into it yet. I've seen some pretty complex ones from the foliage that comes with Forest Pro work OK as well.

Yes, bump mapping is supported. ...And it actually looks better to me as there is no filtering, just repeated raycasting so the map I feel is more accurately represented.

No Including or Excluding yet in the build on the site, but I think Vlado said they were coming pretty soon. I have gotten around it for the most part because GPU does support the control of the Vray Lights' Diffuse, Reflection, and Specular qualities. But yes, these are needed of course.

Best,

-Alan

[tricky]

We are just about to embark on a 10+ interior image project, so I think I'm going to see how far I can go with RT GPU. I think the best thing to do is star the project from the outset with RT in mind, rather than throwing an existing project at it.

I'll push my GTX670 as far as possible, and if things go reasonably well, I hope to upgrade the PSU and stick a couple of Titan's in there. My PSU is a gold series 850W - do you reckon I'd need more for dual Titan?

[Morbid Angel]

yeah 850 should be enough...but if it isn't just upgrade that too...no harm done. All this talk recently got me fired up to get a few titan's also but for my needs the rt gpu just isn't there yet ...

[tricky]

yeah 850 should be enough...but if it isn't just upgrade that too...no harm done. All this talk recently got me fired up to get a few titan's also but for my needs the rt gpu just isn't there yet ...

weve tried a couple of times to get going with it, but never got very far. We'll see what happens.

[vlado]

Well, it helps to get your expectations right; it's certainly not the full V-Ray, but it can do a lot of things and can be helpful in many ways.

Best regards,
Vlado