iRay Not rendering lights
Aabhnormal
Posts: 85
So... I'm having problems with lights. And if there is a tutorial that doesn't invovle video (Because I work a lot at night with sleeping people all around me), just point me at it :D When using iRay, no lights work. I get the ambient occlusion, and I can SEE that there are some lights working... ish... but (As you can see in the attached render), the lights are very weak... even when they are set for 200% intensity. In the set below I have an orange-yello distant light (set for 200%) coming in the window (light sunlight) and a green spotlight (Just to see if I could see it) also set for 200% shining in the window... I can kinda see the light of the distant light... but I can't see the spotlight at all. in the scene mode, the entire model is BATHED in orange and green light from the two lights There should be no white light in this scene at all. The spotlight is only about 10 feet outside the window. I've been having this problem since I started using iRay renders so I figure I have a setting wrong somewhere. I just changed video cards and just now have the horsepower to actually USE iRay, so this is all new territory for me (I use to use 3Delight all the time), and I LOVE the renders, they are incredible! This ambient occlusion is GORGEOUS... but it looks like mid-day... not like sunrise... so can you help me? Thanks! :D
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3Delight and Iray lights work differently. In Iray you don't use the intensity slider to get more light you use the luminosity setting. Ambient Occlusion isn't used in Iray what you are seeing is the light from the Environmental Dome which has settings for using an HDRI as a background and or a light source. It can also be set to Draw OFF and sun and sky only .
Alright, I see the "Luminous Flux (Lumen)" and it's set to 1500. AHA! I get it now... Sunlight would be near 32,000 lux at dawn (If I remember my photography classes) ... This explains SO much! And now the Temperature makes sense as well. Crank that down to about 2000 Kelvin and we have that nice, red, dawn glow. Okay, running the render and I have sunlight! Thank you, sir!
If you are used to photography then go to the Tone Mapping tab and you will find the camera type settings for the scene.
@Aabhnormal "Sunlight would be near 32,000 lux at dawn (If I remember my photography classes)"
Don't get hung up on real life lumen values. You will usually need six figure lumen values for photometric spots in Iray.
@fastbike1
I don't think I've ever needed lumens that high on any lights I've used. I always set them to cd/cm^2 though so maybe that makes a difference.
Lux and flux aren't the same. D|S photometric lights are specified in lumens over the emitter area. An exception to this is the distant light, which has no defined emitter size, and is measured as incident light falling on a given area. In D|S 4.8, the incident light was measured as candles per centimeter square; in 4.9 it's candles per meter square. This makes a value of 10 candles per cm2 -- about noonday sun -- equivalent to 100,000 candles per m2.
The units of measure is available only for emissive objects (so-called mesh lights). For everything else it's inferred; centimeter for point and spot, and (as of 4.9) meter for distant.
How Iray corresponds the luminous flux value with real-world lighting effects has been a point of debate since it was added to D|S. Suffice it to say, what you may know about photography does very little good here. Iray will appear to defy your expectations, so it's best to create sample scenes and experiment with flux values needed to get the results you want.
@Fishtales
I was talking about the photometric spotlights in particular. To the best of my knowledge you can't set units, luminous efficacy, etc the same as with a mesh light, The mesh light really will take efficacy and area into effect, so can be very bright with "lower" settings.
@Tobor "Suffice it to say, what you may know about photography does very little good here"
I think that statement is correct in the context of lighting strength (values), however the behavior of Iray lighting is pretty realistic so knowledge of photographic lighting techniques is useful. I'm pretty sure you would agree.
@fastbike1
I have just tested a spotlight at the default Luminous Flux (lumens) of 1500 using all the Light Geometries and they all cast light on my subject. I did have to adjust the Tone Mapping settings from the default but even at Shutter Speed 60; F/stop 6.00; Film ISO 200, which was the highest setting to give light, there was light. Changing the F/stop down to 4 and or the Film ISO up to 400 gave more light.
Yes, photographic techniques can be used for predicting the effects of light modeling. For that matter, once Iray's lumens behavior is understood, it follows a rational process,too. I've just given up on trying to explain it to people!
On Firshtale's example: There's no question a default spotlight at 1500 lumens will cast light, but I always try to encourage users to develop a standard lighting process, which is akin to how a studio photographer might do it. Most photographers (me, and those I know) tend to settle on consistent camera settings, and adjust lights accordingly. Some of us use LED lamps now, but even with flash this is possible because professional flash units have a watts/second dial to control the output. So given settings of shutter speed 60; f/stop 6.00; and ISO 200, that's roughly three stops from the default tone mapping settings. Iray will respect increasing the light output in reciprocal, so leave tone mapping where it is (or whatever it is you call "normal"), and alter the light(s) to suit.
I'm always changing the geometry size of the spotlight anyway, to control the kind of shadows I want, and here you often need to adjust the lumens to compensate. So for me, it's never just 15000 or 35000 or whatever. but something quite specific for the scene and desired shadow detail.
@Fishtales
Never said the default value wouldn't cast light. It just won't be enough for most scenes. People will then complain about very long render times and grainy results. I also change the geometry of the spots to mimic softboxes.
I used the scene above to produce these the only other light I added was the flame on the match which was Emissive.
I then added a Point Light which I had to boost to 25,000 to keep the settings the same and still get light coming from the windows. Still not in the millions that was suggested. I've also posted the render times and my laptop specs are in my signature. I'm not disputing that millions of lumens don't give more light what I am saying is there is no need for them. I have also done tests and adding more light doesn't always speed up a render, most times it actually slows it down. This one took over 2 days to render and stopped at 94%. This is the same scene only I made some adjustments, lowered the light from the eyes for a start, and the time dropped to just over 2 hours and I left it to go the full 95% ( the reason for stopping the previous one was because it had stopped at 94% for at least 12 hours :) ). What I have worked out is it is the amount of contrast between the light and dark areas which leads to longer render times. Keeping the contrast uniform across the image, no single bright or shadow spots, shortens the render , sometimes by quite a bit.
2017-10-06 22:45:05.808 Total Rendering Time: 30 minutes 20.90 seconds
IRay sucks at lights.
I have two spotlights in a room and its still really dark..
Lumen=100000, Spread angle=maxed out, beem length=maxed out, and Intencity=maxed out.... I don't know what else to do.. XD
Finally got it looking right. after setting each light to litterally one million. lol
Did you change the Tone Mapping to suit the lights?
@Midyin "IRay sucks at lights." "and Intencity=maxed out.... "
It's pretty clear from images posted here and in the galleries that Iray doesn't suck. FWIW, Intensity doesn't do anything for Iray lighting.
Beam angle maxed spreads the light out. A spotlight is typically lighting an object.
Demo 1 is a test render in a room with two spotlights at 100000 lumens each. No other lighting. Shadows are sharp because these are set as point lights. Demo 2 is a single Distant light set at 100000. No other lights.
Don't use Intensity, it's a parameter for 3Delight lights (and has a default limit of 200%). Look at the light's parameters in the Parameters or Lights pane — the bottom half of the dials list is for Iray. Use the Luminous Flux dial, and make sure the Temperature value is sensible for the type of light.
Yeah, IRay is fantastic when we can actually see what we're rendering.
I havent played around with distant lights at all yet, I'll be sure to give it a try...
Nope. I didnt know that was a thing... XD
Yeah, I figured that much out. Thats why Lumen was originally on the list before you cut it out of your quote..
what i originally said was. "Lumen=100000, Spread angle=maxed out, beem length=maxed out, and Intencity=maxed out.... I don't know what else to do.. XD"... Anyway. I finally got it to look right now that I set the Lumen on each light to litterally 1 million... I think the problem is that everything in my scene is set to 500 scale. thats a lot of distence/surface that the lights need to travel over and alluminate.
@Midyin
Tone Mapping sets the camera to either allow more or less light through the lens. Much the same as a real camera.
But that is (probably) what your problem was — you were adjusting both Luminous Flux and Intensity. Remember what I said, Intensity is a 3Delight parameter.
Also when you have lights coming in a room from outside the windows, the architectural sampler can be used to get faster and better lighting.
Thanks for some answers but answer me one thing, do the people at DAZ studio stuff the settings up to try and make you learn functions because i swear i don't change any settings and stupid [stuff] will happen like some prop i just added changes something in my settings causing the whole scene to change attributes, i have to then google and find some setting to switch on or off when i shouldn't of had to do anything because i never changed something, some dumb i prop added did and it's changed my studio's settings so now i have to troll forums to flip a switch somewhere to turn it all back on..
Well, Iray changes - the Architectural Sampler being a case in point. Scene default to saving and loading render settings, since each scene may well need its own (you can chnage this in Edit>Preferences, Daz Studio>Preferences on the Mac, in the Scene tab) and of course a render settings preset can make chnages (HDRIs are saved as Render Settings, so using a preset to chnage the HDRI should prompt a check on the other settings).
I've looked at most settings, i've changed the luminosity, that doesn't work, i have reset the distant light and area light, no light at all in scene the whole scene is now a black shadow, i had changed nothing, just added a Train Car prop i bought in store and the whole scene is just dark, I had not made any changes to HDRI unless the prop did so when i loaded it into scene. Photometric which governs luminosity was toggled off even after switching it back on and turnning up the lumens i still get this black no texture shadows on all meshs in Iray.
I'm stuck on this one scene is toast because everything else renders fine, this prop has switched all lights off, i have checked all settings there all on, everything should be visible in Iray, lumens should be enough and i haven't moved any Sun position or light positions since i started, even when i reset lights or add new lights to a scene no light appears, i believe my whole scene is now broken because i've looked at all render settings, the luminosity settings, added and changed lights to the set, light from skyboxes is not working anymore the only thing that gives this scene light is a 2D billboard back drop of a cityscape the rest has been reduced to nothing but a shadow, totally unrenderable in Iray now when it was perfect before adding this Damn train car scene. How can no light be produced when setting a new light then pointing it at an object.
The HDRI may have changed your Enviroment setting to dome only, when you need it to be dome and scene.
As I said in response to your other post, if this product (which is it?) loads with an enclosure - a sky dome or a tunnel for example - then that will block the HDRI and Distant Lights, and may block other light types depending on placement. When you look through a light any objects set to not cast shadows are ignored, which may make things seem OK.
Thanks for the help. Problem Solved.
Glad to have helped
There's another factor that will keep all lights in a scene (except for Surface - emissive lights) from rendering correctly or at all. It's called "SPECTRAL RENDERING" I had my spotlights turned up in the 10's of Millions in luminosity and - NOTHING! As soon as I turned off the Spectral rendering everything came back gangbusters! It was so blown out you could barely see anything. Spectral rendering works ok for HDRI lighting, but make sure its "OFF" if you try and use any iray lights in a scene. Maybe someone has mentioned this in another post I don't know, but it's worth mentioning here.
I find that ISO in the tone mapping setting will allow more light to pass through the Aperture. The CM^2 factor will increase the intensity of the lights.