Iray - any useful info or tutorials on lights?
Ptrope
Posts: 696
I've rarely used any of the D|S versions, and now we have 4.8 with iRay, a whole new type of renderer and lighting. Is there any good information on how to work with it to produce renders that have any resemblance to the previews? I'm trying to do a test render, and the render was acceptable with no lights and only the headlamp, but I'm using the Dark Elf figure, which came out black, like the Queen in the Marvin the Martian cartoons. I decided to add a point light, something I do on a regular basis in Poser to pick out characters - I'm not looking for realism, I'm looking for clarity and drama. Then I render it, and it comes out washed out. I try changing settings, it comes out washed out. I turn off the light, it COMES OUT WASHED OUT. The preview doesn't look ANYTHING like the finished image. I look through the threads, see a mention of an environment sphere. I turn it off. The picture comes out black. I turn on the point light, the picture comes out black. I turn up the intensity, the picture COMES OUT BLACK. I add a distant light - the picture floods out almost white. I turn it down, down, down, finally it's < 1%, and the picture is still too bright. I find out about the headlamp, I turn it on for the camera I'm using, and WHITE OUT. Keep in mind that now the preview is so dark that I can't see what I'm trying to do, and the render is too bright to tell the background from the figure.
And people like this engine?
What am I missing? Where is some practical information, preferably with examples and comparisons between previews and renders? The only way I can get visible renders is by never adding any lights, because the lights don't behave in any intuitive fashion, at least not what I consider intuitive. For example, which do I adjust - intensity, lumens, Kelvan - I want a program built for artists, not physics majors. Why is there a size adjustment on a point light, but it appears to have no effect whatsoever on the distance of the light's influence - why ELSE would one have a 'size', when I see no "distance" setting for the light. Is there a standard scale so I know that "400" of a light is the same as moving an object "400," or does the light's 400 exist on a completely different scale?
All I can see that makes D|S a program to use is that most of the content at DAZ any more won't work acceptably in Poser. And just so I don't sound like I'm whining, I haven't been much of a fan of Reality, either - but then it didn't come as the default renderer.
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fast render with no problems on lights?
use EXR or HDR images on Environment slot on the iRay menu, set to Dome Only and voila!
cameras?, set headlamp OFF
I'm not looking for an overall lighting as from a dome or any other all-encompassing light source - I'm trying to create a moody light with limited depth, something to pick out a subject. I don't know anything about using HDR images for lighting, but are they useful in place of a point light to highlight a character, which then does not spill over the entire scene?
These are images rendered for the same amount of time - I saw no reason to continue with them when I saw the flood of light in them. One has the point light on at 398% intensity, the other has it off entirely and only the headlamp. I can barely see any difference, even though in the preview I saw the difference - slight but obvious - between having the light on or off.
Point on - 398% intensity
====================
Point off
Yes, we like this engine and we like Luxrender and we like 3Delight.
You can try SikleYield's iRay video tutorials: https://www.youtube.com/user/SickleYield/videos
Firstly, are all the materials in the scene Iray materials?
It does make a big difference for render times, among other things.
Next, there are several different ways of setting the light's intensity...you can pick the units you are most familiar with (many people choose Watts). Then there are the tonemapping/camera settings and they are just like a real camera, in how they work. I can't remember what the defaults are but they aren't really set for indoor renders with lights.
Point lights on iRay are useless, IMHO, the key on iRay is getting full environment light, and yep, with the correct, right HDR file you can get the same effect, example below, more darkness needed?, you can adjust parameters like ISO or aperture, etc etc
First, there is this thing called a Headlamo on your camera. Switch it off.
Second, lights in Iray are controlled through lumiance, not through strength. If you work with the default render tonemapping settings, this means that you will have to crank up all lights lumaince to a starting point of around 50.000 units and go up or down from there. Only exception is the distant light, which needs around 12 units as starting point.
The Environmrnt render settings are set to Dome and Sphere by default. This uses the HDRI in addition to any scene light. If you want less light, use 'scene only'.
Keep in mind that Iray behaves like normal light.
Also, in the advanced render settings, there's something called Optex that you can check for acceleration.
if you want some better information, check the Iray start here" thread in DAZ Discussion section of this forum.
This isn't really a tutorial, but it should give you a starting point. The attached "MeshLights.zip" contains the 3 point mesh light set-up that I created/used to render the attached image. Hopefully this will work, it's the first time I've set up something for DS to share - just un-zip it and copy the "Light Presets" folder to the proper location on your computer.
Be sure to create a new camera to "render through", and turn off the head lamp on this camera. In render settings, go to Environment change Environment Mode to scene only, and you should get results like the attached render.
Good luck!
Couple of comments here that may help.
As someone said, go into Camera settings for EACH camera and under headlamp, switch it OFF. I dunno what the eff it's on by default. That is pure lunacy.
Also, I suggest trying to set your lights to real-world intensities in whatever units you like. I prefer lumens... and what I often do is look up the lumens of the light I am trying to mimic, to at least get it ballparked. If you do that, and then go into tone mapping and adjust your f/ratios and shutter speeds and the like accordingly, so that you are exposing the virtual film the same way you would do it in the real world with this lighting scheme, you will come out with a very nice render that is exposed properly, has good shadows, and looks decent right out of the gate.
It took me forever to figure this out. I had been using the default tone mapping, which is really meant for full outdoor sunlight, indoors with mesh lights and having to set the mesh lights to insane lumens (hundreds of thousands or more) and then fiddling constantly to get the lighting right. This really is not possible in the real world (you can't just add lights and lights and lights of varying intensities unless you're working in a movie studio) yet people get good photos all the time. Because the camera can be adjusted for exposure. And that seems to work best in Iray as well. Set lighting realistically and then adjust tone mapping to compensate.
Thanks, all! I did watch Sickleyield's tutorial - and was struck by how useless the preview is compared to the final result. Add to that the time it takes to render and wow, I'm not sure my frustration levels are capable of that sort of punishment, but as I said, the current situation where the DAZ assets only really work correctly in D|S means I realize I'm going to be stuck with it unless SM get their s*** together soon.
I was definitely surprised by the lumens - also as I said, I'm looking for a program for artists, not programmers, and even though I've justified Poser for years as the virtual equivalent of photography, I'm not a photographer and had no idea that setting the lights in lumens meant going to millions or trillions in the settings - WTF?? I thought I was being insane at "6000"; I didn't know that such a high number (to me) is barely a lit match, probably even <10% of one.
I guess the most frustrating thing is that I've gotten used to seeing a pretty reasonable representation in my previews of what my finished image will be, and now I'm literally shooting in the dark - even Sickleyield's tutorial, as informative as it is, demonstrates that when you KNOW what you're doing, you're STILL just guessing until you render. Like I said, my frustration threshold with software is much lower than in reall life - using D|S is clearly going to turn me into a raving lunatic, and I'm not sure I really want to go there. At least a photographer can see his lights and their effects before he shoots.
DustRider, thanks for the presets - I'll give them a shot; maybe I can dissect them and get a better understanding. Looks like it's all about starting over from scratch - or ditching IRay and going back to 3Delight; honestly, with me, it's never been about trying to get a totally realistic 'photograph' out of Poser, either (or I'd be using the Reality I forked all the money out for, incl. the upgrade ;) ).
Like anything, it takes time to learn. How fast did you learn your last renderer?
It took me about 2 weeks to grasp most of the basics, and I'm still learning bits and pieces. But I have to say, once you learn it, a lot of stuff is WAY easier to set up.
As for preview, if you select Nvidia, it gives you a much more accurate preview. It is resource intensive. It's good for adjusting textures and exposure, but it seems to poop itself if you move anything. (I usually switch back to texture preview for most stuff)
If you use other photorealistic stuff, including some of the mesh lights available for 3Delight, you'll find Iray is actually quite reasonable in render times, for what it does.
I played with iRay a lot for the first two weeks of the beta, dropped it, then came back to it about a week or so ago. I felt like an utter newb predicatbly. I switch back and forth between the two renderers depending on what content I"m using and what I want to do with it but I discovered something important. When struggling with lighting in 3delight I do several test renders that go very fast, in iray I need fewer test renders which go more slowly (my graphic card is old and teeny so my iray renders are done with CPU which is slower).
The upshot is (1) start to finish iRay is faster for me and (2)it's worth it to spend the time learning how to use it
iRay has a preview rendering too, you need a High End Nvidia Card for a reasonable time to previewing:
You can get a good general idea of the Iray lighting w/i 30 seconds if you have a good Nvidia card and a minute or two with a low end Nvidia card. You may need to turn them "on" in the Render> Iray > Advanced tab.
You can always render a small (~750x500) image to get and idea of camera position, lightin, etc.
Here's a 30 sec 750x500 render from an Nvidia GTX780
I'll have to check my machine - it's an HP with the video integrated; I'm not going to buy a card just as one more thing that DAZ is forcing me to change.
I doubt that it is an Nvidia GPU...most likely it is an Intel onboard video chip, with a small chance of it being AMD integrated video. And no, DAZ isn't 'forcing' you to change...Iray does quite well as a CPU only renderer...it's just a lot faster in GPU mode.
I don't see how you think Daz forces anything. The software is free. No one makes you buy any content or use the software. 3Delight works like it always has. Iray is an Nvidia rendering engine, but you can still use it with CPU only rendering. It will just be slow. If your machine has integrated video, you're already crippled for most rendering.
Double post. Stupid new forums.
No no no. Don't do it like that. Millions of Lumens is going to require you to have a teeny-tiny aperture f/ratio and super-fast film speed, which defeats the purpose of even HAVING all those lumens.
Indoor fluorescent overhead lights, like you would get in a school classroom, clock in at around 12,000 lumens. Anything more than that is going to be way too intense for normal camera settings in your tone map.
If you use a single 12,000 lumen mesh light, you can use normal-ish indoor camera settings on your tone map -- 2.8 F/stop, 128 shutter speed, ISO around 800. At least that is a reasonable starting point with a single mesh light aimed at the scene.
Iray is not 3delight. It is designed to mimic real world photographic conditions. Therefore, it is more efficient to *provide* it with real-world photographic conditions. So use real-world light values:
60 watt incandescent bulb =~ 800-1200 lumens
Overhead 4-bulb flurescent bulb bank = 12,000 lumens
Use these as starting points (or something like them). Then adjust your tone mapping accordingly. It is MUCH more efficient to do it with tone mapping than to keep adding lights or to keep changing the lumens on the lights. As an added bonus, although lights cannot be re-set during the render, tone mapping can be (although it will set you back a ways, so if you were at 50% and change the exposure settings, it will hold at 50% and re-render a bit before catching back up).
I'm sorry but NO renderer will be very good on an integrated vid chip. Nor would most video games. Integrated chips are not meant for hardcore graphical stuff.
And barely even web browsing...many/most video cards will do acceleration for video clips, too...
have an integrated video onboard for a rendering is just....
better stay with 3Delight.
...I have a 1GB GPU (Nvidia GTX 460) I bought years ago when I built my system. I originally paid nearly 300$ for it. Today you can get the same one for about 18$ - 25$ on ebay.
Granted it will not support GPU rendering, however it is sufficient enough to use the Iray preview mode in the viewport. It isn't fast but once the view mode is set it will refresh at a reasonable rate for the purpose of checking materials, shadows, and such.
I use a machine with integrated graphics and haven't found it a handicap. I use both Iray and 3Delight. I can surf the web, work in Bryce and view images all at the same time. The machine can get slow or unresponsive at times but that is more down to the way I work it rather than its capabilities
It has 16GB of ram, intel i5 processor with four cores and intel 4000 graphics. I have maxed out the machine quite a few times and it runs really hot most of the time, so hot I have to watch what it is sitting on, I have already burnt my leg with it so it now sits on an upturned tray with a cushion below it and I can still feel the heat
Fish... how long does a typical render in 3DL or Iray take you? I'm just curious.
So far the renders are about even at two hours or so for the same scene. Although for some reason the one I am testing ATM took 65 minutes in Iray and is still going after 3 hours in 3Delight. Once it stops I am going to reload the original scene and try it in 3Delight again to make sure I haven't changed anything to slow it down when I rendered it in Iray.
As always it will depend on the scene too. I have some that render in les than 30 minutes and others that take quite a few hours
I don't uaually check times as I am generally doing something else, either on the computer, reading or helping SWMBO around the house. Being retired gives me plenty of time to wait
I don't agree with the comment made earlier about Point Lights being useless in Iray. I bought an awesome light set from OOT and it uses Point Lights and they work wonderfully....
This has been my experience as well.
I suspect that some of the (early) tutorials recommending very high lumen values didn't fully consider the intent of Iray or look at the developer's blog. As I understand Nvdia's material, Iray is truly designed to mimic real lighting. As such the developer's blog recommends obtaining and using real lighting values. A quick search for photographic studio lighting shows fluorescent lighting units from 200 to 400 watts at 5500K. Various LED units at 3200 to 3600 lux@1meter (~3200 to 3600 lumens) w/ variable color temps of 3200 to 5600K.
These are typical values and not meant to be exhaustive. While spot, point and directional lights can be used, area lights are recommended as more realistic.
I know that I will be experimenting with more real world values and adjusting tone mapping to the kinds of photographic values that I use.
Then again, I could be completely mis-interpreting what I've read (disclaimer).
Prove it, render it.
let me see why I'm wrong.
^^ What, are we in grade-school? There isn't a need for me to prove anything - just trying to set the record straight for other users that Point Lights DO work with Iray.
The product I'm talking about is from Rendo - the promos speak for themselves.
I use a 1 GB 440...no, not very big scenes, but it does do GPU rendering. So, it isn't exactly true that the 460 won't support GPU rendering...it will. It just won't support rendering anything more complex than a quick light test with a few primitives or a single mesh without a large number of image based textures. The lighting test (various IES files attached to lights) were rendering iunder 2 minutes on the 440...in CPU mode thery were clocking in btween 5 and 10 minutes.
agh...nevermind then...