Why is one render taking 58 min to complete but the other taking 5 min?
3DCreations
Posts: 5
Greetings Daz community, I've been having some difficulty with rendering and would greatly appreciate any assistance anyone may have to offer.
So I created a scene in Daz, but everytime I would try and render a frame, it would either take way too long, or be left with a bunch of fireflies (white specs). So I decided to test out a diffrent scene for refrence. I loaded the "Barefoot Dancer Ready to Render" scene that comes included with Daz under the smart content tab. I used the default "Iray Advanced Render Settings" (also under Smart Content tab). The only adjustment made to the render settings was switching to a FHD 1920 x 1080 size.
Rendering a single frame from "Barefoot Dancer" took about 5 min 14 sec.
I then switched over to the scene I had put together myself, and used the exact same render settings. Rendering a single still frame from my own scene took about 58 min 20 sec. About 10 times as long.
I'm not sure what could be causing the extra render time, but I'm hoping someone here might have an idea. I've tried "Scene Optimizer" but it didn't make a diffrence in time and just downgraded the textures. I've also set the render settings to only render thru the GPU. There are no extra assets left over in my scene, but for refrence, here is the office I'm using: The Minimalist Home Office | Daz 3D
My computer is fairly decent, here are the specs:
12th Gen Intel i7-12700
16 GB Ram
Nvidia RTX 3060
I'm still learning as I go, so any advice would be greatly appreciated. And if there is any vital information I missed in my post, please let me know. This is the first time I'm posting here on the Daz forums, I don't know if I get an email everytime someone replys or not, but I will be checking back periodicly for further disscussion. Thank you Daz community.
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Comments
The slow render will be running out of RAM on the GPU and dropping to CPU, most likely. It also possible, if your lighting is an HDRI or SunSky, that it is just taking too long for enough light paths to bounce into the room to reach settled values on the pixels. The log (Help>Troubleshooting>View Log File) should help to clarify. If it is dropping to CPU then you will most likely need to rstart Daz Studio to get teh GPU to work again, even if you do use Scene Optimiser to reduce image sizes.
Thank you Richard Haseltine, I considered RAM might be an issue, but during the rendering process, I monitored the computers use of ram, and it never went past 10 or 11 GBs of the 16 available.
And as for needing to restart Daz to get it to only render thru GPU, I turned off the CPU rendering option a while ago, so there have been many restarts since then.
I don't believe this is a hardware issue, otherwise both renders would be taking a long time to complete. If the scene included with Daz renders quickly, then I must have something set up incorectly in my own scene. You mentioned lighting as a factor that could delay render time. That is certainly a setting I haven't moved very much. It could be worth checking out.
Also I just realized my screenshots aren't visible. Let me attempt to repost them. Thank you again.
Richard is refering to RAM on GPU (VRAM), which is different from RAM. If your scene can't fit in VRAM, then it can't render on GPU.
Try to look in the log for each of the 2 renders, and you can see whether it used GPU or CPU.
In your scene, just try : hide the node TMH Office Ceiling and TMH Office Wall Window 1 by Ctrl + Click that Eye icon in Scene pane. Add a spotlight (if there's no light in the room) pointing to the figure. Render, and check the progress bar to estimate the time. It could be much faster.
Then let's see...
you can actually see how much RAM/Video RAM is in use while your renders are running, if either are close to full you'd know where to start. Look at Task Manager/Performance:
VRAM consumption of your scene is appro. 4GB. Check the available VRAM as Squishy mentioned or with GPU-Z before Rendering.
Hiding ceiling and that wall will reduce nearly 1Gb VRAM consumption and resolve "lighting issue"...
Do you have RTX 3060 12GB or RTX 3060 Ti (8GB)?
Wow, what a great community, I didn't expect so many replies. Thank you to all, let me try and reply to each of you.
PerttiA and felis: My GPU is RTX 3060 12 GB VRAM. I also make sure not to have any other tasks or applications running while rendering. Seems like it should be more than enough for a scene with so few assets, but I could be wrong.
crosswind: I'm going to give your advice a try. I'll keep track of the render time, and post a screenshot here with the results.
Squishy: I'll keep the task manager open like you suggested, and keep track of the VRAM. I've kept track of the RAM before, but never the VRAM, so maybe that could be it.
Again, thank you all, I've been trying to solve this issue for a while now, hopfully with the advice I've recived so far, I can get closer to the solution. I'll be back to post my results.
keep in mind there is a lot of variability in render time just based on what you're rendering, especially complex materials with reflection, refraction, emissive materials etc.
Hello again everyone, sorry for the delay. I upgraded to Daz 4.22 and didn't realize I would need an Nvidia driver to continue rendering with Iray. Needless to say, it took me some time to figure out why nothing was rendering after the 4.22 update.
So I followed the advice given all of you gave me, and am glad to report they did indeed make a diffrence. I turned off the visibility on TMH Office Ceiling and TMH Office Wall Window 1, then hit render. Same exact render settings as before, this time taking 14 min 46 sec. (I've attached the screenshot below)
While rendering, I monitored the VRAM and the RAM. The VRAM stayed at about 6.8 GB of 12 GB the entire time. A few moments it peaked over to 7 GB, but never more than the available 12GB. The RAM was a similar case, staying at about 10.22 GB of 16GB.
At this point, I don't believe hardware is the cause of the long render time. It seems more probable that the office asset itself may be the problem. I tried rendering with the entire office visibility turned off, and was able to complete a still frame in 0 min 53 sec. (Screenshot also attached below)
I'm going to attempt a render with the same character in a diffrent enviroment, and see if I get results closer to the "Barefoot Dancer" render.
I'd love to hear any additional thoughts or suggestions from anyone. Am I just being too impatient or are renders supposed to take this long? Am I missing anything important I haven't tried yet? Any and all advice would be helpful. Thank you again Daz community.
Iray works by tracing the path of light rays, sending them off at different angles from each source at each iteration. Those end up hitting a pixel and determine its colour for that sample, over the course of rendering Iray keeps averaging out all the values for a given pixel until it is "converged" - has reached a stable value, how stable is determined by the Render Quality setting - and when enough of the pixels are converged (the Render Converged Percentage) the render will stop 9assuming ti hasn't stopped due to running out of time or samples). The more convoluted the path is from the light sources to an area of the image the fewer paths will reach it, and so the longer it will take to stabilise. When you have most of the light at a distance and there is a setting enclosing the area of interest you are greatly limiting the amount, and direction, of light that is illuminating the scene. Removing obstructions will help, but of course it looks unnatural; alternatively add local lights (Spot or Point, or emissive surfaces) with Scene included in the Environment Mode setting to help illuminate the tricky areas.
The more times light has to bounce, the longer the render will take. This can be slightly offset by adding more light. The harder Iray has to work at defining what is lit and not lit will also dictate the length of the render, i.e. dim or faintly lit scenes.
I've experimented a few times with Guided Sampling for interior scenes, and like all things it's entirely dependant on the scene. I suggest trying it out - either it'll improve the render time, or it will take a bit longer but look a bit better.
"Removing Celling" or use iray Section Plane to cut it out is a frequently-used way to improve the render quality and time, as the "culprit" is Emission on the ceiling. Emissive lights usually severely increase the time of light bouncing and noise, let alone there're always poorly-set property values there.
I illustrated the reason and tricks as the screenshots down below:
Wow, thank you crosswind. I can't tell you how much I appreciate the visual aid screenshots. These are going to be very helpful.
And thank you to both Richard Haseltine and kraftwerkd for the further advice reguarding light.
It's been a few hours since my last post, I had to run out to work. But I'm back now and am eager try out all these ideas and advice. I will of post screenshots of the results as soon as they are done.
Thank you again Daz community.
Update:
So I tried out the 2 options recommended to me by crosswinds, as well as a thrid option I decided to experiment with.
Option 1 involved increasing the luminance and max value path. I set luminance to 1000 and max value path to 10. In hindsight I may have gone overboard with luminance at 1000, but it was still interesting to see the results. Render time came in at 34 min 7 sec. (Screenshot attached). Of course the scene is now way too bright, but I plan to experimant with this setting further in the future.
Option 2 produced the best results at 13 min 5 sec. (Screenshot attached) The final render was well lit, with no visible obvious fireflies. This option seems like the path to follow for future renders.
The third render I've attached was a combination of option 2, and an idea given to me in one of the first posts by crosswinds, where I turned off the visibility on the celiling, wall 1, and just for experiments sake I turned off the floor as well. Interestingly, it shaved the time down to 9 min 4 sec. (Screenshot attached). However, the lighting feels just a tad too dark. It might be worth leaving the floor on, or even moving around the luminance setting some more.
Above all, the answers and replies here have taught me that rendering requires trial, error, and experimentation. There is no universal formula, as every scene and its respective assets are going to be a unique combination. I believe these ideas have set me on the right path towards getting quality renders in a resonable time. I know this will require more time and patiance to get just right. I don't know if I'll be getting anymore replies on this post, I'll still check back periodicly, but truly to everyone who took the time to assist me, thank you. This is a fantatsic community that I hope to interact with more in the future.
Thank you.
That's right, the more experiments you do, the more practical experience and tricks etc. you're gonna have. This scene is a very typical case in which you may learn a lot, especially from the renders with diffrent "options".
For instance, why the render of 3rd option was even faster but looks darker ?
1) Technically, you may hide even delete the objects (or use iray Section pane) which are not within the aspect frame in Viewport to reduce VRAM consumption and save render time. For an interior scene, the less objects (geometry) there are in the scene, the less paths of bounce there're gonna be and the more render time you're gonna save. So, as you also deleted Wall 1 + the floor, the render time was further saved by 30%. If you further delete the whole office but just leave there a man + a chair, I assume it may only take appr. 90 seconds to complete a render.
2) Then why the man looks darker ? because of the bounce as well. The less paths of bounce there are, the less light the objects in the scene are gonna get. So that's why after we decrease the max path value, we have to add more Luminance on the source of lights. It's the same theory. You should've increased the value in Enviroment Map slot, or better add a splotlight in front of the man.
PS: For playing with such an interior with tricks, an ambient light + 1 or 2 mesh light(s) could be a good combo...