Some Clarification About Iray
404nicg
Posts: 270
I'm sure I could find the answer to this if I dug through the forums or something but please…give a lazy person a break on a Sunday.
I'm thinking about getting a computer with a quad core processor to upgrade from my current dual core. Does the graphics card HAVE to be made by NVidia in order for Iray to work? Is that what I read somewhere? Also what kind of specs should I be looking for as far as cache on the graphics card? Thanks for the help
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Iray will run in CPU mode with ANY video card...but it isn't really that much faster than any other CPU only renderer. On an Nvidia video card, if of recent vintage (Gtx400 series and newer...I wouldn't count on anything older than that), it can use GPU (if the scene fits in the card's memory) or a GPU/CPU hybrid mode. To take full advantage of GPU rendering the scene must fit, entirely, in the card's memory...so it is recommended that the card have 4 GB or more of dedicated, on the card memory.
Thanks…so is Iray a faster renderer than some of the other unbiased render engines?
I think so. I tried Luxrender and 10 hours got me a grainy image of a candle.
Iray can bang out cool stuff in 10 minutes.
Thanks…so is Iray a faster renderer than some of the other unbiased render engines?
In GPU mode...definitely.
In CPU/Hybrid mode...maybe.
No. Not really. People should never really use Luxrender on NVIDIA hardware.
No. Not really. People should never really use Luxrender on NVIDIA hardware.
Luxrender doesn't care (much) which GPU you have. To clarify: If your PC supports it, Lux can use OpenCL to do GPU/CPU hybrid rendering, which is (marginally) faster than CPU alone. However, unless you're using the (development only, at this point) SLGRenderer for Lux, you aren't doing pure GPU rendering. I've tried Lux with SLGRenderer and can say that the speeds are similar to that of Iray. However, since SLGRenderer is still in development, it's buggy, a little cumbersome, and not as nicely integrated as Iray.
Iray is faster than other unbiased render engines which DON'T use GPU rendering. It's probably relatively on-par (speed wise) with others that DO use GPU rendering (like Octane or Lux with SLGRenderer.) And Iray will only utilize GPU rendering if it's on an NVIDIA card.
As I said, not really. There are other renderers with unbiased methods that are much faster than iray even when using only a CPU. Iray is also slower than other GPU renderers on the same hardware.
As I said, not really. There are other renderers with unbiased methods that are much faster than iray even when using only a CPU. Iray is also slower than other GPU renderers on the same hardware.
Are there plugins or bridges from DAZ Studio or Poser for these faster unbiased engines? I'd be very interested in learning more if there are -- it would be very useful! Since I pretty much only use DS and Poser (with a little Vue on the side), my selection of unbiased engines is limited.
Unfortunately, only Octane and Luxrender have exporter or bridges for DAZ Studio or Poser. If you like to use other renderers, you need to do an OBJ/Collada/FBX or Alembic export, depending on the import format the renderer supports.
Unfortunately, only Octane and Luxrender have exporter or bridges for DAZ Studio or Poser. If you like to use other renderers, you need to do an OBJ/Collada/FBX or Alembic export, depending on the import format the renderer supports.
I was afraid of that. Alas, I don't have any other engines at my disposal, save Mentalray, which is NVIDIA-based anyway, and doesn't do GPU rendering. I think I read somewhere that there's a GPU accelerated Mentalray in the works, but I don't think it's out of public testing yet. I've got 3DS Max and Maya, and I've tried bridges and alternate-format exports to utilize these programs, but I've found those options twitchy and cumbersome, when they work at all. Other unbiased, standalone commercial engines are way out of my price range. I haven't even invested in Octane because of the price. This is just a hobby for me, so it's hard to justify anything more expensive. :(
I'm a little confused about hybrid mode. Are we to understand that, if the scene is too big for the VRAM on the NVidia card, then neither GPU only nor hybrid mode will work? Or will hybrid mode enable the GPU to help out with some of the processing under any circumstance?
I used Reality and Luxrender (not GPU mode) happily until quite recently. Then I started getting blotchy red hotspots on several skins. I am not sure whether this coincided with the release of Reality 4 (which I bought) or with my conversion to G2F characters from predominantly V4 characters. These later materials have SSS as default and so does Reality 4. The red blotchy noise seems to be a Luxrender/SSS problem. I was told on the Reality forum that the spots will go away eventually but I have left renders going for 20 hours and they were still present. Previously, with V4 skins, I was reasonably happy with the results after two hours.
I've only tried a quick test with iRay but even a simple scene was too large for my measly 2GB GeForce MX680M. So, at CPU only speeds, it was painfully slow. (I have an iMac 2012 with an Intel i7 and 24GB RAM)
I'm still trying to come to terms with 3Delight lighting and surfaces but there are so many variables that I find it almost impossible to get a consistent render quality. If I was only doing portraits of one character in a simple scene, it would be easier but in scenes involving rooms, furniture and 2 or 3 people, the results are so very unrealistic. That's after having spent all my pocket money on AoA Advanced Lights, Amazing Skins, and various other 3Delight "quality assist" products. I've also followed advice on Gamma Correction and specular-only lights and any number of other tips.
What version of the Beta are you using? Iray render is a lot faster if you put the optimization for speed in the render settings, rather than memory.
Also, in the Advanced tab, check OptimiseX and the CPU. You can try and check the GPU as well, but that might end in a crash if the function is not properly supported by your card (AFAIK only newer models above a certain level support it).
Thank you for that. As I said, I've only tried it sparingly so I have not followed any tutorials or guidelines. Therefore you are right in suggesting I really need to find the optimal settings. I'd still like to know how the hybrid mode works though.
When you say faster - is CPU mode anywhere close to 3Delight speeds? Luxrender in CPU mode is probably 5 or 6 times slower than 3Delight but the results are more realistic (unless you hit the red hotspot problem). Also, Luxrender will grind away in the background leaving me free to work on the next scene. Does Iray block the Viewport for any further work, by the way - I am in the middle of something with DS 4.7 right now so can't check.
Speed depends a lot on what lights you have in the scene, and what quality level you are going for.
Some images in Iray need longer than 3Delight, others are way faster even in CPU mode only.
For example, using the default HDRI lighting and a simple G2 character, the Iray render, on my PC, clearly beats the 2Delight render.
EDIT: As for the "Working while rendering", you have the same limitations as while rendering with 3Delight there, but on the bright side of things, you can pase a render and resume it at any time as long as you don't close the render window.
That's interesting, thanks. With Reality, I generally used a coupe of mesh lights only but I read somewhere that IRay is actually faster with more lights in the scene (surely not?). I think the lights are different to either Reality mesh or DAZ Studio defaults (or A0A), right? But it is encouraging that you say it can be faster than 3Delight even in CPU mode.
Does it have support for HD and displacement? Any issues with geo-grafting? Do you set up the skins for 3Delight then render in IRay or do you need to start from scratch with skin settings?
Sorry - I know there are some really long threads on Iray but I'll get around to wading through those when I actually start playing with it properly.
My experience is that you need some minimum amount of light or Iray really struggles, but after that I don't think more helps. It may, at some point, start taking longer again, but I haven't tested it specifically.
But when I've, say, tried to have a dim scene lit by one or two candles... hoo boy.
MOre light in Iray will make it render faster
Assuming 'more light faster' but you want a dark or gloomy render, you can adjust that with tone mapping. (Sort of like how TV shows used to do most 'night scenes' during the day and just put a filter on)
Interesting more light in Lux slows it down. Rendering using R4 takes much longer due to using SSS on skin but renders look much more vibrant then they did with R2 having said that a much faster Lux 4.1 is apparently is coming in the next few weeks. I will try Iray once the official version of DS is released since I don't do DIM or betas I have an AMD fire pro card. GPU rendering as it stands in Lux does not work well IMO...
This took between 12 to 13 hours http://fav.me/d8sw11e (Iuxrender)
As I understand it, the reason more light means a faster render is because of the two types of calculations done. The first/primary is bounces calculated directly between the light and the objects in the scene. The second type of bounces are indirect and it takes many more of those to fill in all the blanks. More lights mean more primary bounces which help fill the scene in faster.
Well, I downloaded the latest beta all ready to have a go with IRay. Then I started looking for tutorials. The first I found was this one by SickleYield: http://sickleyield.deviantart.com/journal/IRAY-519196777
And, she starts by saying this:
So, am I about to waste a lot of time learning about something I can't use? I can't afford to throw money at a new computer. I have an iMac which cost a lot and, as I'm retired with no company pension, it will have to last. These iMacs are not upgradeable but you couldn't pay me to go back to using Windows. Perhaps those of you who are getting decent render times using CPU have ultra-powerful processors?
[EDIT] Reading the comments under that tutorial, the point is confirmed over and over that CPU only is not worth the effort. Think I'll give this a miss and go back to trying to get decent results in 3Delight or wait until Luxrender is fixed for the SSS problems.
The tutorial is based on the first Beta version. Things have improved since then for CPU render times.
Maybe give it a try and render a couple of images, before not trying it all all, because of something that might, or might not be true for your system. :-)
I understand your point but in order to be able to assess whether it will work for me, I will have to put in the hours learning how to set it up, what lights and shaders to use, etc., etc. It isn't just load a scene and render, I'm sure.
Someone else made the point that IRay is free because NVidia want to sell cards so they will not put much effort into making the CPU option work quickly. Luxrender is free because it is Open Source and developed by non-commercial volunteers. By all accounts, Lux 1.5 will be very quick. I just hope it can render SSS without those awful red hotspots.
So, in short, do I give a few hours over to testing IRay or do I continue with 3Delight until Luxrender 1.5 via Reality 4 is available in a few weeks?
Try IRay. You won't regret it.
Ok, ok -- I'll invest a few hours.
Jeez, you guys can nag ;)
I'd try just "Set up the character and render away" option. You might get positively surprised. :-)
Well, I doubt just testing Iray is gonna be a waste of time. Sill, I would be surprised if Iray in CPU mode gave you a really significant edge in render speed vs lux 1.5. And from what I understand Iray, unlike lux, will still freeze up DS and plunder your system resources.
I'm still busy reading about Iray stuff and watching tutorials but I've noticed that something seems to be screwing up my iMac display. I get artefacts popping up, not just in the viewport, but on my desktop too. I have installed the latest NVidia Cuda drivers but still getting them.
[EDIT] Restarted DS and have not seen those artefacts again yet.
I almost did as you suggested but I did follow a few guidelines. I have a scene with only G2F and her default skin but I selected the Iray Uber surface and the G2F Optimised material. A single distant light with headlamp turned off. GPU and CPU ticked, Optix acceleration ticked and Instancing Optimisation ticked. I reduced the render size to 400x400 so as not to be too taxing.
3Delight would take less than a minute to complete for such a simple scene. After 7 minutes with IRay and my iMac fans whirring like crazy, I had an image with lots of noise in the high specularity areas - bright white dots. It said 70% on the progress bar but it had been saying that for a few minutes.
Then I deleted the distant light and added two spot lights. in 3 minutes 30 sec. it was at 90% with very little noise. So I'd call that progress - tiny steps :)
EDIT: A clean image of the same scene but at 1500x1500 size took 10 minutes (I stopped it at 93% because it seemed stuck there).
Try rendering with just the environment HDRI that comes as default setting, no extra light, camera headlight turned off. :-)
As for the distant light, that one doesn't decay with distance, and you have to turn it waaaaay down to not fry the scene. You have to set the luminence for it to 10 or lower (default is 1500).
Depending on your graphic card, you might get faster renders if you just tick CPU in OptimizeX. I actually got slower renders with GPU ticked there as well. :-)