IRAY Rendering Advice

dmgalan

I've just started playing around with IRAY and really love the quality and the features, but render times are so bad that it's impartical for me to use it. Even with a single base figure, render times have exceeded 8 hours. I'm curious if my render settings are causing the issue, or is my PC not strong enough to handle it. Do I need to change my NVIDIA settings? Any suggestions would be greatly appreciated.

My config is:

Processor: Intel Xeon E5-2687W v3 3.1GHz (9.60 QPI) (25MB Cache) (10-Core)
System Memory: 32GB DDR4 2133MHz Crucial (ECC Registered) (16GB x 2)
Graphics Card: 1x NVIDIA Quadro K5200 8GB
Operating System: Windows 10
Daz3D Version: 4.8 Pro Edition (64 bit)

 

 

 

fastbike1

IMO, it's likely your settings. The original render for the attachment is 1500x1909 and completed in about 25 minutes on an I7 w/ a 3GB GTX 780.

I generally use the default Ira settings (7200 sec / 95% convergence / 5000 samples. Even complex scenes complete in the two hour limit at resolutions of 4000x3000

 

The second file is a 3Delight render converted to Iray.Originally at 4000x3000. 104 minutes. (Edit 9/27/2015: I've learned alot more about Iray in the last few weeks. This render takes about half the time now).

Tobor

A K5200 has over 2300 CUDA cores. Your Xeon is no slouch, either. So your machine is certainly capable of some very fast renders, assuming it's set up properly.

The first thing to do is perform a small test render, then immediately look at Help->Troubleshooting-View Log File. Look especially for errors that prevented the Quadro from participating in the render.

(If it doesn't show up at all, you might not have included it in the rendering devices. Click the Advanced sub-tab in the Render panel, then on Hardware. Make sure both your card and CPU are checked. For now, turn off OptiX acceleration for both, until you've figured out the reason for your rendering issues.)

Do you have any other nVidia cards installed in your system?

 

Tobor

Addendum to above: be sure your drivers are all up to date, and I mean the latest to the day. nVidia recently came out with a driver fix for Windows 10 that causes some slowdowns and other issues. Not sure if this includes the Quadro line, though.

tring01

Your render times are horrendous for the quality of hardware you're running.  I'm not trying to be critical.  Mine were worse when I first started messing with IRay.  Here are a few lessons learned.  Take 'em for what they're worth.

1. START your workflow by configuring your render settings!!  Do NOT try to do this last as it will cost you tons of rework.  Why?  Because IRay is designed to respond to light like a real world SLR camera.  The default render settings, under the Tone Mapping tab, are set up for a typical outdoor shoot at mid day.  They are NOT optimized for low light or indoor work.  They're so far off in fact that you see lots of recommendations to push your lights to 1,000,000 lumens and beyond to compensate!  NO!  Those huge lumen values on your lights throw light all over the scene and suck up tons of processing power for nothing.  I recommend that you make one of two choices.  ​
   1. IRay remembers your render settings from session to session.  First step in creating a new project is to re-set your render settings to default if you're doing something much different than the last one you worked on.
   2. If you're planning to shoot an exterior scene use only the Sun Sky setting in the IRay engine to light your scene.  Set your sun for around mid-day, then the default Tone Mapping settings are a good start.  
   3. If you plan to use any other type of lighting the first thing to do is set your Tone mapping settings to something more realistic.  I would recommend an ISO of 400, Shutter Speed of 30 and F Stop around 2 as a good start.  You WILL want to revisit and play with these as you tweak your scene before final render.  For very low light simulations you could push the ISO as high as 1600, the Shutter Speed to 15 and the F Stop to 1.6.  Don't be afraid to experiment with the Crush Blacks and Burn Highlights.  You can get some amazing looks with just those two sliders alone.
2. Beware, beware, beware of assets with non-IRay optimized shaders.  IRay HATES non-optimized shaders.  Check out this video by Sickleyield.   She does an excellent job explaining how to optimize your scene with 100% IRay shaders.  She covers so much so fast you will probably find yourself going back and watching it again and again.  I did.  I got more out of it every time.  She does get the light settings wrong though.  She recommends pushing the lights insanely high, but we discussed tha above.  Just as an aside, I was optimizing a render for an animation recently.  I will include one image below.  I got the renders down to under 5 minutes per frame and started the render.  Then I noticed that I forgot to apply the IRay shader the the characters' hair.  I stopped my render and junked the results I'd gotten so far (the hair looked like plastic anyway).  When I applied the IRay shader to her hair it not only went from looking like plastic to looking gorgeous, but my render times per frame dropped from around 5 minutes to less than 2 minutes.  From just that ONE wrong shader.
3. Delete anything form the scene that you don't need.  In the render attached I had a backdrop, but since I was simulating a night time shoot it was barely visible - so I just deleted it.  I replaced it with a primitive cube 30 meters on a side.  I applied the IRay Uber shader to the primitive and set the color AND the glossy color to black - so that it would not reflect any rays back and thus reduce the load on the render.  It cut my render time from 10 minutes a frame to around 5.  Lesson learned - if there is anything reflecting light in the scene that's not adding value to the render worth its' "cost", delete it.
4. Avoid mesh lights, like emissive primitive spheres or planes.  You can use them if they add to your scene (like glowing panels on a spaceship set, etc.), but light your model with the standard three light setup (Key, Fill, and Rim).  There are a million tutorials out there about doing that.  Be aware that the standard lights in Daz3D 4.8 are the photometric lights mentioned by people using 4.6 or earlier.  They just changed the name.  You don't need to buy any fancy lighting packages.  Trust me.  I spent probably $200 on fancy IRay lighting packages that I never, ever use.
5. Never use a sky dome.  Never.  Don't try.  Unless you want to burn a few days of testing for nothing.  Instead, you can add an HDR image to the IRay Dome environment setting, but I don't like the way that works either.  Buy a backdrop for your scene and be sure to apply the IRay Uber shader to it.
6. Finally, don't forget to optimize your render Progressive settings.  IRay is a progressive (iterative) engine and it will iterate for an infinite amount of time if you let it.  You need to do test renders and decide how good is "good enough".  Dialing back on the progressive settings will dramatically shorten your render times (like, cutting the time needed by 90% in some cases - no BS).  You have three main ones.  Time, Iterations, and Convergence.  They all work together so changing one effects the others.
   1. Time.  This is the "big stick", and is the one slider I use most for single scene renders.  The default is 7200 seconds.  Try some test renders at silly low settings like 60 seconds and see how it looks.  Dial it up slowly until you get acceptable quality.  It's a very, VERY steep curve.  You will be amazed at how little your render will improve by giving it more time beyond a certain point.  I've not found a properly optimized scene take more than 30 minutes to get photo real quality on my crappy laptop (which your machine could eat as a light snack before lunch).  Be advised though, complex scenes (multiple models - three or more) will take more time to reach an acceptable quality level.  Sometimes much more time.
   2. Iterations and Convergence.  When rendering a series of images for an animation I use these two sliders.  I start by dialing down convergence to around 60% while test rendering a more simple frame, and then raising it slowly until the render is good enough for me.  Usually somewhere around 86% to 89% is where I end up.  But that's just me.  I could probably get away with 75% for animation work - but I'm picky.  Then I test render some of the most complex frames of my animation and note how many iterations it takes to get the quality level I want.  I dial back the iteration to just a hair under that.

Using the method above I achieved the attached render on my Alienware gaming laptop with an Nvidia 730M card in less than 2 minutes.  I know it's not photo quality, but I'm rendering for animation and the process of interlacing the images into a video will eliminate all that granieness.  

dmgalan

Thank you so much Fastbike1, Tobor and Tring01!

I'm already seeing a dramtic improvement in rendering speed. I really appreciate your comments and feel much more informed now. Thanks again!

tring01

Put up some renders when you've got things cooking.  I never get tire of seeing what others are achieving.  Good luck!

SpottedKitty

tring01 said:

IRay remembers your render settings from session to session.  First step in creating a new project is to re-set your render settings to default if you're doing something much different than the last one you worked on.

One other tip for making things easier — one of the "Save As" options in the new D|S version is now "Render Settings". Once you've got everything the way you like it, save the settings. This lets you have several different presets for different purposes. Note that this includes the HDRI Environment map if you're using one (all other lights are part of the scene, so they get saved in the scene file).

ALLIEKATBLUE

tring01, your explanation is so in depth I'm gonna print it and study.  My question is kind of simple I think.  I need some advice on iray render settings for a very dark skinned character.  It's a V4 skin and she looked beautiful in 3delight but in iray she's horrible all I can see is her eyes. Nothing is in the scene just the nude character because I had to do a test render because she looked so dark. Do I need special iray shaders for dark skin? Here is a link for the character.

https://www.renderosity.com/mod/bcs/?ViewProduct=104253

tring01

ALLIEKATBLUE said:

tring01, your explanation is so in depth I'm gonna print it and study.  My question is kind of simple I think.  I need some advice on iray render settings for a very dark skinned character.  It's a V4 skin and she looked beautiful in 3delight but in iray she's horrible all I can see is her eyes. Nothing is in the scene just the nude character because I had to do a test render because she looked so dark. Do I need special iray shaders for dark skin? Here is a link for the character.

https://www.renderosity.com/mod/bcs/?ViewProduct=104253

Yeah, you absolutely need to apply IRay shaders to her to get her to render properly.  I don't use V4 so I don't know what IRay products are available.  I recommend you watch the Sickleyield video here  because she manually updates the shaders for M4 in that tutorial using the stock IRay shaders that come with Daz. She has to do a few tricks to make it work.  She covers a lot very fast so you may have to watch it several times.  I did.

One thing she doesn't mention is that you can use the stock IRay shader for Water Thin Film, on V4's eyes to get them in line.

Good luck.  Let's see a render if you get it working.

tring01

dmgalan said:

Thank you so much Fastbike1, Tobor and Tring01!

I'm already seeing a dramtic improvement in rendering speed. I really appreciate your comments and feel much more informed now. Thanks again!

My pleasure.

Couple things I forgot to mention.  I really like to think and use IRay like a camera.  It makes everything very natural for me.  When you create a camera in your scene IRay defaults it with a  65mm lense.  That's a nice mid range lense.  Did you ever do portraiture with a 65mm lense?  No?  Me neither.  I like to change the lense to something more appropriate for the scene.  For close shots I usually change it to 50mm or even 35mm.  You can actually get a fish eye effect by pushing it down to 20mm.  It is really amazing how sophisticated the software is at replicating the optics.  Just such an amazing feature.  Why not use it?

Once you get the right lense for the shot then turn on the depth of field feature.  That really gives you a LOT of control over your scene.  You will find that playing with your F stop in the render settings, Tone Mapping, now effects your depth of field too.  You have to set your focal length in the camera tab of course.  To have access to all these photography elements in a software program is just thrilling.  You can sit at your computer and compose dream environments with dream shots in minutes.  So fun!

Couple other things on lighting.  Beware the scene preview lights.  You can turn them on and off with CTRL + L.  They're supposed to turn themselves off when you render, but I don't trust them.  I turn them off manually before I start the render.

Headlamp.  There is a kind of vendetta in these forums against the camera headlamp.  I actually (gasp!) like to use the headlamp when appropriate.  It's a perfectly normal spotlight that is attached to your camera.  Most of the time you're going to leave it off, but on those occasions where your three light rig (or your Sun Sky for outdoor shots), is putting just a bit to much shadow on the model's face you can turn on the headlamp and dial it's intensity down to where it just knocks down those shadows perfectly.  Just don't forget you have it on if you change up the scene.  I think that's why people advise turning it off all the time.  So they don't forget to adjust it properly before rendering.

Good luck with your renders and have fun!

 

geoff6

Yep, probably one of the most useful threads in getting to grips with Iray.

Thank you for the nuts n bolts explanation, it's opened up Iray to me at last!

G

talihawk

I've got a question. Which tab is best to play with ? Max samples, or Max time? I've done some large renders lately around 4000 x 5000 or so, and left the computer to render over night. But when it's finished the image still has some graininess to it, so I'm guessing that the time or samples ran out leaving the image 'unfinished' due to the alotted quotas. Also the time is recorded in seconds correct? I know I've had renders go longer than just 2 hours in Iray.

 

Problem is I'm not sure which option was reached first. Thanks for your help!

 

 

Fishtales

Try Max Time at -1, Max Samples as high as it will let you and leave the last one at either 95% or put it up to 98%, seemingly putting it at 100% doesn't work as it never reaches 100% :)

talihawk

Thanks Fishtales :)

talihawk

One other Question :) Is there an advantage over using the camera settings in the Iray tab vs the controls on the camera itself?

Fishtales

The settings for the camera only set the DOF (Depth of Field) if you are using it. The camera settings in Tone Mapping work like a real camera where the different settings  allow either more or less light into the 'film' so you can use less light and get a light image or more lights and get a darker image etc.

talihawk

Thanks Fish. :)

ronmolina

Fishtales said:

Try Max Time at -1, Max Samples as high as it will let you and leave the last one at either 95% or put it up to 98%, seemingly putting it at 100% doesn't work as it never reaches 100% :)

Actually for me I set it for 100% and it does reach it. For small scenes less than 5 minutes. Very large complex scenes 2 to 4 hours.

 

Fishtales

When I say it doesn't reach it I mean Iray doesn't converge the scene to 100% it actually stops before then although it says 100%. I'm sure it as one of the DAZ developers that said it although I'm not sure.

Tobor

A simple scene (ex: a primitive sphere) will reach 100% convergence in fairly short order. This is pretty easy to test. There's no technical reason why, given an appropriately lit scene, convergence can't get to 100%. Convergence simply means a preponderance of samples to a given pixel fall within a certain range of values. On certain types of scene, however, getting to this point may not always be quick or easy.

For more complex scenes, it's very much the 95-5 rule: The first 95% takes 5% of the time, the last 5% takes 95% of the time! If you had the machine to do it, it should be possible to get that last 1%.The exception might be if Iray simply cannot determine if a pixel is fully converged -- a near-black pixel, for example, or some pixels with "noisy" neighbors.

In the Iray docs, the default is stated at 0.95, which is 95%. They warn against going higher, and say it should not be necessary, but they do not mention 100% is not physically possible. It's better to alter the Rendering Quality setting, which increases the threshold of when Iray considers a pixel converged. That's more controllable, and the increase in render time is approximately linear with the increase in Quality setting.

The idea is that instead of trying to get 100% of the pixels estimated as converged, which may not result in much visual difference (and may take a month of Sundays), instead, increase the requirement of how Iray considers each pixel is converged.

 

Fishtales

I knew I had read it somewhere.

http://www.daz3d.com/forums/discussion/comment/909986/#Comment_909986

Tobor

Yes, I've read that, but nVidia's programmer's documentation makes no mention of this, and you'd think it would. There are a finite number of pixels, and if 95% of them can reach convergence, then mathematically, all of them can, eventually.

It's possible, I suppose, that internally Iray treats 100% as 99.9%. We'll never know that, but from a standpoint of valid input, the Iray documentation specifies valid values of 0.0 to 1.0 (0% to 100%). See near the bottom of the page below. If 1.0 (100%) would lead to to an infinite render, the docs would say that.

http://www.migenius.com/doc/realityserver/latest/resources/general/iray/manual/concept/progressive_rendering_photoreal.html

 

 

SpottedKitty

Fishtales said:

The settings for the camera only set the DOF (Depth of Field) if you are using it. The camera settings in Tone Mapping work like a real camera where the different settings  allow either more or less light into the 'film' so you can use less light and get a light image or more lights and get a darker image etc.

Another advantage of using the Tone Mapping controls is it adjusts the scene as a whole, not just one camera; you don't need to remember which camera you were using the last time you were fiddling with that scene.