Tips for fast Iray
Oso3D
Posts: 15,009
The thread on 3dl got me thinking; 3dl in Daz Studio 'naturally' is set to a fairly low level of realism. It's capable of fairly realistic looks, but you really have to push it and get familiar with it.
Most people then think '3dl is so much faster!' Well, no, as the realism of 3DL approaches that of normal Iray, I find that in many ways the 3DL renders start swinging around in the same ballpark as Iray, in CPU mode.
But for those interested in working with Iray, it's worth looking at ways to reduce 'costly' render elements.
Tips:
Refraction and translucency. Shut them right off. If you want glass, use the old basic 3DL trick of setting Cutout Opacity to .1 or something and make the glass very reflective (possibly use Metallicity). Same deal with water, though you probably want opacity around .9.
With people, this will look bad in close up renders, and you may want to be careful with lighting, darken the skin a bit on later skin textures to make up for the lack of translucency effects. But you will be surprised in how many renders it's not that obvious.
And heck, if you are going for a toon effect, no translucency plus flat colors will save you a lot.
And while we're at it, replace all mouth textures with a blank white preset (you could save a material preset, or whatever you want). That will save you a bunch of textures you aren't going to be seeing. (And if you are, consider replacing with simple colors)
Don't do volume effects. Fog and similar suck the render engine dry. Better use simple prop effects, like https://www.daz3d.com/epic-props-godrays-volumetric-light-for-iray (although be careful with emission, too!)
Instead, do it in post, possibly use a distance canvas to mask effects over distance. This costs a LITTLE render time, but not nearly as much as simulated fog.,
Go into Render Settings/Optimization, and set Max Path Length to 3. Default is -1, which means light paths bounce a HUGE amount, getting a really subtle wonderful perfect glow. Well, nuts to that. 3-5 is more than enough for most purposes, making for much speedier renders.
Enjoy and add any other tips you've noticed!
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Comments
...but what if in a large scene you need that depth haze (volumetric haze)? Or you want all the streetlights illuminating the area undrneath them with proper shadows (emissive lights).
Take a lot of that away and you get the "Poser4" look.
...also what if you suck at postwork like I do?
Then it’s slow. Just like 3dl.
And the postwork involved doesn’t require dexterity.
I mean, I’m not sure how bad the emitters for street lights would be. I’ll try it!
Thank you for the great tips, Will! :D
I often like to take renders into FotoSketcher or other programs for artistic postwork. In those cases, lengthy detailed renders are wasted, because a lot of the fiddly detail and subtleties are going to get lost when you apply oil paint or whatever.
And with those I actually find Iray's ability to 'stop whenever' a real boon.
Oh, another tip:
Render at double size, then run through Photoshop's Despeckle, and shrink. Iray will often leave a lot of annoying fireflies in a short render, and these steps will eliminate them adequately.
Using these tips, I did these. The first render took 3 minutes in CPU mode, the second took 5 minutes in CPU mode.
The first scene, After the War, had a lot of refractive glass. I replaced them with simple opacity settings. The water took a little fineagling; I think I went with a slightly blue, metallicity 1 surface with Cutout Opacity .9
16 GB of RAM, Intel i7-5820K CPU @ 3.3 GHz (12 CPUs)
A good machine, sure. But not a turbocharged anything.
...for a full scene I do not find 3DL slow at all as long as you don't use UE. Again the test I did of the scene with the girls at the bus stop using AoA's advanced lights and a few lighting tricks illustrated quite the opposite as even with pre render optimising, the 3DL version completed in 1/8th the time of the Iray one. The only emissives I used were the car taillights, the bus destination sign, and the monitor in the shelter.
...as to post, when you have to paint in shadows being cast by objects on one plane onto those on another, it does. I've used Mood Master back in the day and that required compositing several planes to get a good illusion of depth. AoA's atmospheric camera eliminated all that.
As to street light emitters. I had to abort rendering Stonemason's Urban Future 5 as it was just taking way too long, over 4 hours and it was still very grainy. Haven't used the set since save for a daytime sun light test I did for someone with all the emissives turned off and no other effects. At 900 x 600 that took just over an hour to render. Also in my railway station scene there are ten platform lights which slow the process down a quite bit.
Not having PS I have no "despeckle" filter, this is why I use the noise and firefly filters in Iray which unfortunately also slow the processs down . Boosting rendering size also requires more memory. I'm already dealing with the process of dumping to much slower swap mode the way it is.
Yes, 3dl isn’t that slow if you keep it simple. But you can make Iray more simple.
And if you compare apples to apples, the speeds are comparable.
For example, do that Urban Future with UE2 and indirect lighting from ambient surfaces (or AreaMesh) and I guarantee it will take at LEAST as long as Iray.
As for the postwork... I was specifically talking about fog and haze, which doesn’t require manual dexterity.
Despeckle, Photoshop was one example. I suspect most image editors have something similar.
If you don’t like Iray, that’s totally cool. But I think a lot of people have a mistaken impression about what it can do.
Gimp has a "despeckle" filter
Here's Urban Future 5, using my tips above. 5 minutes at Iray CPU making a Beauty and Distance canvas.
Converted Beauty to 16 bit, despeckle, shrink. Converted Distance to 16 bit and shrink.
Used Distance as a layer over beauty, set it to 'linear add' and an opacity of, oh, 15% or so.
First image is that result, second image is the same run through a minimal Oil Paint Photoshop filter to smooth it out (there are countless options, many free, to do similar things).
My computer costs ~$2000 on Dell, and you can probably get something similar for a lot less if you shop (and if you don't care about the graphics card, well, save another few hundred)
Oh, and for cartoon renders you probably want even lighting. I recommend actually using the camera headlamp and making sure to have as much even light as you can.
Also probably best to remove glossy from all surfaces.
And if you use AoA ambient light for occlusion, AoA spots for streetlights and ambient color +linear lights with no shadows for neon signs I guarantee you will get a descent result 5 times faster:)
Oh don't get me wrong, I basically hear what you're saying. Both engines have their strenghts as you said. I just think if you dumb down IRay too much it is pretty close to the famous poser look, why take away the photorealistic touch just to render fast in IRay? I have very little experience with IRay so forgive me if I can't understand you 100%! But if you disarm IRay you might aswell use 3DL and it will render faster still?
Sven: My point is that people are comparing dumbed down 3DL render speeds to default 'everything turbocharged' Iray speeds. Well, yeah. That's going to look slow for Iray.
But I wanted to show Iray users that they don't have to leave everything turbocharged if they don't want, and they have just as much ability to yoke down to get faster, less realistic renders in very short amounts of time.
Again, none of the above examples took me more than 5 minutes on a fairly standard modern computer without even touching my graphics cards.
Like, personally, I like doing art postwork filters (FotoSketcher), toon style stuff, and so on. Well, I've come to realize I can do most of that in Iray. I don't need to use 3DL, and I can still do it fast.
Outlines are still a problem, but then the only outline solution I'm _really_ happy with is Linerender9K, which is a weird in between thing.
You say ‘why not use 3DL’ but that’s from the perspective of somebody comfortable with 3DL. Perhaps consider the thread to be ‘how to render fast using Iray materials and without buying anything in particular’?
Yeah, I'm not liking Glossy on the surfaces of cartoons either.
I haven't used 3Delight in along while but I did some experiments with lights in Iray and the results are on my Art thread.
https://www.daz3d.com/forums/discussion/comment/2904886/#Comment_2904886
I also did some other rests using black an white boxes placed around the viewport, I can't show them here as I am not near my computer, but I found that it depended where the bright area was in relation to the dark area how fast the render went. There are more examples with render times on that thread too.
Fair enough, point taken:)
tip 1: not really a speed tip, but it could be if you run out of GPU memory for your scene to fit on the card...
Never have a web browser open in the background, even if its minimized it can eat a lot of GPU memory. I just found this out the other day actually. Had firefox running but minimized in the dock, with maybe 7 tabbed pages (none of them showing, all docked in the one minimized browser). It ate up over 1GB of GPU memory. I thought the latest version of Firefox should be better than this with memory but apparently not.
tip 2:
OptiX Prime Acceleration. Its under the "Advanced" tab for your render settings and is off by default. Enable it (check it), but don't enable it until you are ready to render your scene.
Don't have it enabled while you are still working on your scene and scrolling around with your viewport in iray mode, as it will slow down your draw rate considerably.
It sometimes speeds up rendering iray scenes considerably, but at the expense of much slower viewport iray draw rate and increased memory requirements.
I've been testing this a lot lately, and sometimes I see the difference in memory usage will jump from 4GB to 5GB if I enable Optix. With a 6GB card I am fine, but if you have a 4GB card it could crash you or dump the scene to CPU. But the speed boost in rendering is usually substantial, although sometimes I see hardly any difference at all, it seems to depend on whats in the scene.