Why Does Iray Still Render SO SLOW?!
DrowElfMorwen
Posts: 538
Let me get a few things out of the way: it's not running out of memory, it's not overheating, nothing is being throttled because anything is getting overly worked or too hot. My comp specs, listed below, are MORE than enough to handle anything DAZ needs to be doing.
To be clear, everything else runs fine, it's just rendering that seems ridiculously slow.
I'm using DAZ Studio 4.21. I haven't updated to 4.22 because I haven't heard any good reason to do so, and that it changes how it processes lighting and any previously made scenes are ruined by it. (Someone please tell me that's wrong?)
My Comp Specs -
Intel i7-12700K LGA1700 600 Series 125W
ASUS TUF Gaming Z790-Plus LGA1700 ATX Motherboard(PCIe 5.0, DDR5, 4xM.2 Slots, 16+1 DrMOS, WiFi 6, 2.5Gb LAN)
64GB Corsair Vengeance-DDR5 RAM
NVIDIA RTX 3060 graphics card (12GB)
Corsair RM850x SHIFT Fully Modular ATX PSU - 80 PLUS Gold - ATX 3.0 - PCIe 5.0 - Zero RPM - Modular Side Interface
Corsair 4000D Airflow mid-tower case
Noctua NH-D15 chromax.black air cooler
1 8TB Seagate Hard Drive
1 2TB NVMe M2 Hard Drive (where DAZ is actually installed)
I am currently trying to render a scene at 1524 x 924 with two Genesis 8 characters. Both are at SubD 3, one has 1 geoshell, the other has 2. There are a few props in the scene but not many. Three lights, one HDRI. It takes over 5 minutes to get to 473 iterations. I decide to change it, so I close out DAZ, open it all again, change to one light and a different HDRI. Somehow, the rendering speed got WORSE.
Next, I've dropped both characters to SubD-2 and hid one geoshell I didn't really need, and it seems to have improved the rendering times (7 minutes, 1394 iterations). But it's still REALLY slow to me....
QUESTIONS:
- Is it still true you need to close out DAZ (either 4.21 or 4.22) to clear out RAM/memory from using Iray Preview a few times? Does DAZ STILL not have the ability to clear out such memory OR an option to do so without closing the scene or program?
- What else can I do to make sure I'm absolutely getting the BEST performance possible?
- Is DAZ just horrible at rendering? Is it NVIDIA? I have an RTX 3060 card, so....
- How to view how much geometry by numbers is in my scene?
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Comments
With my RTX 3060, I'd generally expect an exterior scene at 2400x1800 to render to 2048 samples (I like powers of two) in about 10 minutes if it's a pure HDRI background, 20 minutes with a simple exterior background with direct light, and 30 to 40 minutes with an interior.
You said it took over 5 minutes, but I'll round that down to five - which equates to 2.2 Megapixels per second. At its slowest (a 40 minute interior scene), my 3060 is rendering at about 3.6 MP a second, and considerably more than that at other times, so it does sound like something may be wrong.
What assets are in the scene? I've found that some hair assets can *really* bog down a render (Iray certainly had a problem with intersecting transparencies that some hairs could trigger, I'm not sure to what extent that's been fixed).
Well, for the moment, I would like to know how you found out what hair assets are bogging down a scene. Did you do it manually by taking those hairs out, then rendering? Or could you actually conduct a test or look at something that *showed* you how it was bogging down? If the latter, this is a skill I need to have, and Iand I would like to learn.
By the way, checking up on my render after 2 hours and 13 mins, it's only at 4226 iterations. This is utter MADNESS.
Editing for Another Update: I changed the lighting in the scene for a third time. After 29 minutes, I'm at 6132 iterations. Not bad. But this isn't the lighting I originally wanted. And it still leaves the issue of, how can I check to see what's working "against" me in a scene versus what's good?
Among the great lack of consistency with DAZ items...
You don't say, is your RTX 3060 card a 12GB or 8GB version.
The DS log can help in figuring out the problem (Help->Troubleshooting->View Log File)
Checking VRAM usage, GPU-Z at https://www.techpowerup.com/gpuz/
Usually an instinct of "this is rendering way slower than it really should", knowing what kind of things are likely to be the source of the problem, and then isolating which of the potential candidates it was.
Here, the small area of the werewolf's tail visible halved the speed of the render. I didn't have a suitable replacement at the time, so had to persist - but it's since been replaced in her character preset by another tail asset that doesn't have the same problem.
You have a lot of opaque/transparent surfaces with reflectivity like in the hair, water, glass and so on would be my guess.
PerttiA, It's the 12 GB version. Again, I'm monitoring my computer as its rendering--Thanks for the link to CPU-Z I guess, but I already have it. This is why I was able to say it's not maxing out, overheating, etc. And to be honest, if I came back and said it was the 8 GB version, let's be clear, that doesn't actually matter so much when taking everything else into account. The issue is NOT my set up, it's Studio's various products--some are clearly better than others--and DAZ itself not keeping up so much with the times. You'd think by now it'd be able to handle a lot more geometry, but other programs like Blender and Vue can handle high geomeotry like a breeze. Why can't DAZ?
Matt Castle, awesome picture, it made me laugh! Yes, I had a tail like that once, too--it added to render times like mad! It's a shame DAZ doesn't seem to have a way inside the program to see what's heavier to render than others. I really was hoping there was a way to do that.
Nonesuch, I have two wine glasses, and I suppose skin and hair could be reflective enough, but that's about it. I do know render times sped up a lot when I changed my lighting for a third time.
Now that makes me wonder. If lighting is the issue, what works better? Why do some HDRIs add so much render times and others don't? Why also the same with various in-scene lights?
When the GPU runs out of VRAM, it is usually after geometry has already been loaded into VRAM and it will stay there even when the textures did not fit and the rendering is done on CPU.
When the GPU runs out of VRAM and rendering falls back to CPU, it is reported in the log - Have you checked the log?
I have nothing constructive to add to this thread, except to say that in my experience a very slow render is almost always hair or lights, but mostly I just came in to tell Matt Castle that I love that image and it make my morning better.
Render times dependent on complex calculations. Reflection add to calculations, transparencies add to calculations, and the number of light rays and ray bounces add to the calculations.
Bottomline, it depends on what's actually in your render. I generally render at HD 1920 x1080, with a 3060, and my renders are in the 2 - 3 min range.
It was directly copied from a shirt a friend had showed up in recently before I did it, but I figured that in my universe I could actually make the joke of putting it on a werewolf.
(In my universe, werewolves keep their mind in both forms and shift mostly at will, but I won't derail the thread further by burying it under lengthy descriptions of my setting's mythology/lore).
Also if you add volumes, then just forget it. I'm working on a scene right now and my test renders that are about 800 x 1080 are taking about 15min on my 3090 just to get to about 80% convergence. And that's 100% because of the the volumetric lighting.
My rendering is being done on the GPU, it didn't fall back on the CPU, and it's a 12GB graphics card. I don't know if you saw my reply before someone edited my post, but this wasn't and isn't the issue. I would like to ask if there is a way to flush the VRAM without closing out DAZ altogether. Is this a thing yet?
No volumetrtics are most of my scenes, but I know if I add them it's definitely going to be an overnight render.
Check for surfaces that have 0 glossy roughness and are not 100 refraction weight. In my experience that will kill your render time like mad. Just increase it like .10, you'll get shiny surface and faster render time. Any time I add a prop or set to a scene and find the rendering time went off the side of a cliff it's usually due to to that.
Also check for props that have emissive surfaces that have very high lumen rating. If you load a fluorescent light and the bulb surface is set to like 35,0000 cm2 lighting value, that will also kill your render time and create fireflies aplenty. Lower the emissive surface emmission value down and slap a ghost light to generate the bulk of the light.
Scene-based VRAM consumption is released (99%+) after you saving Render or closing Render window. Iray Engine consumes appr. 2-2.2GB VRAM the moment you press Ctrl + 0 or Ctlr + R, this part of consumption can only be released after closing DS. Since the VRAM consumed by Iray Engine can never been reserved for Scene itself, to me, there's no big difference if you close DS, well... saving Render or closing Render Window is good enough.
I think more or less you're doing it well... In general, run DS exclusively , leave unused VRAM to DS for rendering AMAP, monitor VRAM Used by GPU-Z... Consider using Scene Optimizer if you have a big scene to render.. However, as for the scene itself, most of the time it will be case by case. For instance, sometimes you just hid a ceiling, then 60% of rendering time has been reduced (emmissions + their light bounce had gone...)
Personally I don't think so...at least not horrible, but Iray Engine may bring you slow rendering from time to time due to various reasons... People complain that Iray Engine consume too much VRAM but if one renders the same scene with Cycles in Blender, he/she will find Cycles engine even consumes more VRAM. Well... Cycles is faster, has more lighting options and a good denoiser filter. Comparably, if you render with Arnold, Redshift, Renderman, etc. those engines require more complex settings... so on & so forth. So to me, there's no 100% perfect render engine. Quite a lot pre-requisites and dependencies....
Therefore currently, well using the card you have with the most optimized scene as well as the render related settings in DS may be a good way out.
You may view the geometry data with Scene info. plugin: Window - Panes - Scene Info... In general: 100K polygons consume 10 - 15MB VRAM. Per SubDRenderLevel + 1，VRAM consumption of geometry x 4
BTW, what's the version of your Nvidia Card? If it's 546.01+, some new feature like "preventing Rendering from 100% fallback to CPU" may bring some unexpected issue...
Again, as PerttiA mentioned, you've not posted the log, so we only have to guess by now...
What does your GPU-Z usage look like when you are rendering? This is what mine looks like rendering in iray using a 12GB 3060:
Pretty much same as me. Only difference when I use my favourite character with skin having a -1500 lumen/cm^2 emissivity to emphasise skin-skin shadows (think armpits, under chin etc) it seems to add a couple of minutes.
Regards,
Richard
I don't think I will agree
Unfortunately. I have to perform the procedure shown in the attachment basically every time I try to render.
DAZ Version 4.22.0.15
I'm guessing that in your example, you ran out of GPU memory and dropped to CPU rendering. My guess is based on my own experience with pushing an 8Gb card to the edge of it's memory limits. There is a serious "memory leak" in Iray where it doesn't release all the memory used in a render, and renders will eventually drop to CPU. Some scenes I've done that were right on the edge of the memory limit on my 8Gb card I could only "render" once before dropping to CPU, that included preview renders. Turn Iray on in preview, switch back to texture shaded mode, then try to render and Iray would drop to CPU. Save the scene, open "new" scene (to make closing DS faster), close DS, start DS and opened the scene, go straight to render and Iray is happy and doesn't drop to CPU.
I agree with what FirstBastion said about complex calculations significantly impacting render times. In my experience, reflection, refraction, complex transparencies, SSS, lighting, volumetrics, DOF, etc. all impact render speed.
OP, curious as to what your render settings are. I can render two G9 figures at SD3, with a low complexity environment, using an HDRI, a spot, and sometimes a fill, at 2800x2000 on a 4070 in approx 2 minutes. When I was using a 3060 I would average around 3-4 minutes with 2-3 G8 figures in a similar environment.
Without seeing the scene, there is simply no way anybody can help you with it. It could be anything.
You can run the benchmark scene to verify the 3060 is running correctly. Beyond that people are just going to be guessing, and it is purely a crapshoot as to whether anything said is going to help. You haven't disclosed what your render settings are beyond resolution. Are you using default settings? What is your render quality? Are you using the caustic sampler? Or the guided sampler? Did you alter the Iray compression settings?
Each of these can impact rendering in their own way. And 7 minute renders are not that bad. If you were on CPU you would be looking at hours. The 3060 may be considered a bang for buck GPU for Iray, but it is far from being the fastest GPU for Iray. It is a full 3 years old and is on the lower end of the performance spectrum for what you can buy new. Its main claim to fame is its 12gb of memory, not its speed. There are going to be things that are slow to render because simulating realistic lighting with complex materials is still pretty hard to do, even with faster GPUs.
Geometry is probably not your issue, it is probably a material. It could be the skin, some skins are quite complex. Or it could be one of the hairs. You can hide the hairs for a test to see what happens. Or the clothes. Some hairs and clothes for Daz are especially resource heavy. Sometimes it is not obvious why. I have a short hair by OOT that takes forever to render for some reason. A different short hair that is fairly similar takes a fraction of the time. It is actually so bad that I avoid using this hair, even though it looks really good.
Even the camera angle can be a factor. How close up is your camera? Close up shots tend to take longer, because of the complexity of skin. I can have the same exact scene, move the camera away from the subject, and find it renders much faster than it did up close to the subject's face.
But like I said, these are all guesses. There are countless things that can be going on in your scene causing it to slow down.
Games are cheating to get a believable result to render in 1/30 (or even less) of a second and as a result, none are as GPU intensive as an Iray render. And on a 1080, you're likely not playing a recent game with Ultra settings activated.
There is a fair chance you aer simply running out of video RAM and dropping to CPU. Please don't post much the same comment to multiple threads, I am leaving this one since it provides more information than some of the others.