Iray and ambient light
Hera
Posts: 1,958
Hello!
I wonder if there's a way to use ambient light together with Iray.
I use it quite often for monitors, bulbs, fire / flames, led indicators and so on, and upon using Iray they all turn black, or at least not glowing. Is there a way around that - like blowing up the percentage. And if so - how much? I now have a TV set with the ambient percentage as 500 - and it's still not glowing.
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No. In Iray you would instead apply the uber base shader to those items and turn the emission color to white to make them give off light. You control how much light with the settings that appear when you set emission to white.
Iray has true emission surfaces...so if you want it lit, you turn it 'on'.
3Delight CAN do true emission surfaces...except there are no emissive shaders in DS, hence the Ambient 'hack'...because, years ago, that was easier than trying to get the emissive shaders, which at the time were almost all 'production' shaders, working in DS. And, many places only used the emissive shaders when they absolutely had to, most of the time the ambient hack was used, even in major motion pictures.
But...that's changing...
DS does have a 3Delight emissive shader, uberArea.
To clarify what the always helpful SickleYield has said, you most likely would set the Emission color to White when you're trying to make a television monitor become an "ambient" object (Emissive in Iray). Just apply an Iray shader to the surface and change the Emission settings. Make sure you put the image (Diffuse map) into the Emissive map/color space... then you're all set.
White is not a requirement. You can set the Emission color to whatever color you want. If you need some kind of color fidelity for a television screen, then white is probably the right color... but it doesn't have to be white.
For instance, I use more orange/yellow for a candle flame Emissive surface in order to ensure that the candle is not giving off pure white light to the surroundings.
And you can also plug in an image map...
Thank you all of you! You're all awesome!
I did as Sicle suggested and it worked just fine, and then I realized it was possible to add a image too, just as mjc said - and it got even better because it looked more like a TV and less like a glass painting lit from behind. That is, the colours were more distinct and the dark parts really dark!
I'm still experimenting away - Iray is a new world and I'm trying to be as darings as with 3Dlight.
It sometimes helps to set the Emission temperature to 6500K (Close to white) This usually allows the map to control the color of hte light better, at least in my experience.
I've noticed what Spooky is talking about here. Lower or higher temperatures will affect the light color, so if you want to use a map or tint the light, stick to 6500.
I've noticed what Spooky is talking about here. Lower or higher temperatures will affect the light color, so if you want to use a map or tint the light, stick to 6500.You can tint with light color/map or temp or a combination of the two. I have found, for personal use, that it is, usually, easier to adjust tint in one place than try to balance the two places.
As usual YMMV. (Your mileage may vary.)
As usual YMMV. (Your mileage may vary.)
You bet.
OK, I'm flummoxed - I keep reading about "emission" but I see no control called this. I've got my Interocitor model, which has 2 screens and various bulbs that I want to have lit, as they do in Poser. They 'glow' in the preview, in the color selected under Ambient - they are totally black in the render. How do I make these surfaces glow in an Iray render? Most of the advice I can find online loses sight of glowing materials; everyone heads right to "add a light to the scene and set the ... "- this is NOT A LIGHT! It's a surface! This thread seems to point in the right direction, but I don't see the controls mentioned here as part of any surface in the model. "In Iray you would instead apply the uber base shader to those items ... " which is where? I see an "!UberSurface base" with a red teapot sitting on a surface, applying it adds a lot of controls to the surface, and none of them are "emission" or anything like it.
I'd like to be speaking the same language as the rest of the community - it just doesn't appear to be the case.
The Iray Uber Base shader is under Shader Presets - Iray.
I hope this helps.
...yeah I tried to set up an ambient light in a scene I'm working on using a flattened cylinder primitive with the emissive shader and it totally slugged the render process. I kept getting the same convergence percentage showing over and over and over again for hours and this scene is no where as complex as others I have created which rendered in less time.
I thought that Iray liked a lot of light, guess I heard wrong.
So you found the culprit. Good. And it is true Iray likes light. Very early on, while 4.8 was still in beta, I sped up one render with a spotlight above and behind a figure, barely touching her.
But emissive lights and photometric lights are not created equal, so to speak. I've recently read that emissives have many surfaces, and Iray has to calculate the light for every surface. I assume each polygon is treated as a surface, but that's really a guess. Regardless, it appears we should only use emissives for items that appear in the render. For light that originates off camera, it is better to use the standard photometric lights. And for outdoor renders you can use something like the sky for Watersong Isle in the environment map and get a nice soft ambient light. Indoors is a little trickier, but bouncing light off the ceiling or a wall not in the render can work to give a soft light in an enclosed area.
OK, I'm gonna work through this step-by-step
At the top of the Editor tab, it says "omUberSurface" - is this correct or is this a case where the correct "Uber" shaders simply are not present at all, and this is someone else's shader set? I would hope that, since 4.8 is supposed to be all about IRay, that that particular shader set should be installed as a matter of course.
The Iray shaders are here:
Shader Presets/Iray/DAZ Uber
If this path is not there, you didn't install the 'Default Lights and Shaders for DAZ Studio 4.8+' package with D|S 4.8. Or, if you did install the package, it wasn't done correctly, and needs to be done again.
None of the !Uber... shaders will work properly in Iray. They are 3Delight Shaders. You're wasting your time.
There is no need to guess about where the shaders are, or what they are called. Download the 'Default Lights and Shaders for DAZ Studio 4.8+' package and open it with any unzipping program. Follow the Content\Shader Presets\Iray\DAZ Uber path, and you will find the necessary Iray shaders are there.
If you cannot find an "Iray Uber Base" then you don't have the Iray shaders installed, just as Tobor mentioned.
If you use the DIM to install products, as I suspect, check and see if they are already there, waiting to be installed. Open the DIM and type "default lights" in the filter field, above the "Installed" tab on the right. There should be a "1" in one of the green boxes on the tabs. If you don't see a "1", click on Display Hidden on the Ready to Download tab. If you still don't see a "1" in any of the green boxes, you will need to download the file. You will find it in your Product Library, https://www.daz3d.com/downloader/customer/files. Type "4.8" (without the quotes) and hit enter, and just the DAZ Studio 4.8 Pro will display in the list. Click on that and then scroll down the page to find the download links. To download and install using DIM, click on the green button.
Once the file is in DIM, click on the download button. If "Install After Download" is checked, (the default,) the file will be installed immediately after downloading.
Once the file is installed, you should uncheck the Display Hidden option.
OK, reinstalling the default DAZ lights and shaders put them into the menus (the DIM showed them properly installed the first time - no idea what the problem was ... ).
However, even though the colors or images chosen for the Emission Color channel show up in the render now, they show up only as diffuse colors - there is no illumination in them at all. I don't even mean that they aren't illuminating the scene - the materials themselves are no brighter than having light reflected off of them. I've tried upping the Luminance channel to 10000, and again, they glow just fine in the preview, but not in the render.
At least now, we are "talking the same language."
It may take a lot higher value than 10,000 to see any light. Try setting the Luminance value back to the default 1500 and then changing the Luminance Units to kcd/m^2.
As for colors, putting a color in Emission Color won't change the emissive color of the item. To do that, you need to change Emission Temperature. I found this wiki page helpful: https://en.wikipedia.org/wiki/Color_temperature
I found Real Lights for DAZ Studio Iray real helpful, too.
I would first check in with render settings/tone mapping and get exposure at reasonable levels; I like shutter speed 32 and ISO 800.
And putting a color in emission color DOES change the color, though you should pick temp 6500 or so if you are going to be trying to do it; if you change color, you can give the light an artificial color, like cyan. If you set emission color to white and change temp, you get realistic light at various temps.
I was testing it before I made that comment, Will. When I used a color in the Emission Color, it still rendered white, but the light falling on the object around it was the color I put in Emission Color. Maybe the Luminance was up too high for the color to show? I don't know. I haven't worked much with Emission. It slows down my renders to a crawl. lol
If you choose cd/cm^2 as the luminosity units, then you keep the same unit scale that the rest of D|S uses, which is centimeter. You get very bright output with just a value of 10, which is 10 candles per square centimeter. That's a good mount of light to produce a self-lit object.
For the color of the light, do EITHER one of these:
1. Dial color temperature to 0. Now, the color is whatever you choose for the emission color.
2. Set a color temperature to mimic a real light type (e.g. incandescent, etc.), and choose an emission color. The output is the emission color multiplied by the blackbody radiator of the color temperature. Since few people can estimate the resulting color is in their head, either use the standard whitepoint of 6500, leave the color temperature at 0, or be prepared for a little bit of experimentation.
Be careful of setting a too-high luminosity. It can "burn out" the color and you end up with a much lighter color than the one you specified. If you need a bright output while keeping the basic hue, increase the saturation of the color.
This is a combined five stops faster. Why would that be a "reasonable" level for a properly lit scene? If you're needing to alter tone mapping to this extent to get the right exposure, there's probably not enough light in the scene, and this is the major contributior to slow renders.
There's a reason Iray defaults to the combined tone mapper values that it does: ISO 100, f/8, and shutter speed 1/125 (D|S tweaks that to 1/128, for their own reasons). If possible, light to this exposure value, then adjust as necessary. If tyou don't give the engine enough light, you have to expect slower renders and more grain.
L'Adair : I think high Luminosity values tend to 'blow out' color toward white.
I do not know if anyone's hit this exact angle on the ambient light question, but what I've been wondering is if it's possible to make an Iray Photometric that behaves like the AoA Advanced Ambient light with respect to the way it essentially "draws" light in to a focal point, as opposed to radiating light like a point light. I guess you'd call that an inverse point light. In any case, it was the physics of that light I really fell in love with.
On the topic of ambient light, however; the greatest weakness I've found with Iray has been the absence of a good ambient lighting solution for interior/enclosed settings. I've played with a few ideas, like high-transmissive and low-opacity mesh lights, and I suppose one could try to set up the emissive property as some varient of the old ambient surface hack, but I can't say I've found something with simplicity and ease of use I'd expect of a good lighting solution.
I'll keep poking at it, though, well beyond the point where I'm sure it's a dead issue.
Although i havent played with them myself maybe a solution is to play around with LPE profiles. I dont have any links to places to get them....i recall someone who posts often has a clicky in their sig. From what i understand LPE profiles can plug into the emissive property tab and it uses that information to make the light behave like the real world counterpoint of that light sources. There are LPE profiles for anything from flashlights to super bright LED sources and everything inbetween.
As far as the photometric spots in Iray, play with all the goodness there you can change the emitter profile to be rec., disk, cylinder, sphere. or a point light. Change the size of said light emitter. (smaller has harder shadows, larger has softer shadows) Mess with the spread angle...and the beam exponent of the spot light as well for interesting effects.
Daniel
+1 THIS. I agree with Tobor wholeheartedly on these.
For non-incandescent/non-flourescent lights, or simulating lights casting through filters, it is best to set the temperature to 0, and use the emission color or use an image in the emission color. If you look up the standard Planck locus charts for temperature(K) vs emission color, getting some colors are almost impossible. This is why for incandescent/flourescent lights to produce other colors in real world lighting, they try to get as many colors as possible in the emitted frequencies (6500K is pretty close to white) and then put a color filter on it. But doing this in Iray just creates unneeded complexity and slows lighting calculations down significantly. Real-world now uses LEDs and such for a lot of the colored-lighting effects lamps, due to the ease of getting specific colors out of properly designed diodes. These allow for much finer control of where in the locus charts the emitted colors are.
And PLEASE change your luminosity units to cd/cm^2.....it makes things MUCH more workable, with no values in the millions for lumens just to get the scene to be decently lit.
And for interiors that are basically not using any 'environment' lighting...turn ON the Architectural Sampler. It does make a big difference.