How are you supposed to light up an Iray Render?
nokoteb99
Posts: 931
I usually render stuff with 3dDElight as i was not aware of IRay and how cool and realistic it is.
I tried taking my old saved file of just a set/scene and render it with iray. Result: Pure black image with tiny points of color. And yes the render finished.
I have bought scenes from DAZ(Deans office etc) which came setup with iRay and while those are completely black in the DAZ viewport. When i render them they turn out well lighten and bright. I don't really know how they lit their scenes and why they look black in the viewport but when rendered they look excellent.
So what's different, betweeen how you should set up lighting or whatever in Iray vs 3DDElight?
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Comments
First thing to learn,
CTRL+L
This turns on the Preview light. Basically it makes the black scene visible in the viewport regardless of lighting used.
You can also turn it on via the Window>Preview lights on the menu strip.
Second thing,
3delight scenes don't work in iray.
The first difference is that iray 'lights' have the Photometric option set to on. without this on you won't have any light in the scene other than the hdri or sun settings, depending on render settings used.
The second is that the auto conversion from 3delight to iray is pretty crap. Most surfaces are changed to a metalish surface with high reflections.
The last thing is that iray lights are mathematically more accurate, meaning the further away a light is, the less light it adds to a scene.
For the most part lighting between 3delight and iray isn't that dissimilar.
The only difference is, mainly, the options.
Unlike 3delight lights where the main focus is on intensity, for iray lights is a mix of Intensity, beam exponent, Luminous flux and temperature
Temperature defines the "color" of the light in degrees kelvin. It's a bit subtler than just changing the color of the light, unless you go to the extremes.
Lower values are closer to the red end of the spectrum while higher values are closer to the blue end.
Luminous flux, determines the "brightness" of the light, higher values are more intense. The defuault of 1500 is almost invisible unless the light is right up against something, or you use a heck of a lot of them.
A setting of 5-30k is what i use for "standard distance" setups. but for some instances i may use 300k-1 million or more for backlighting to produce that "halo" effect on people.
Beam Exponent has to do with how the light diffuses over distance, at the default of 4 it adheres to the "inverse square law" where the distance from the light source is inversely(decreases) proportional to the intensity of the light.
Intensity isn't as important as it just becomes a multiplier of the lumens. It's usually better to adjust the lumens as opposed to the intensity.
As far as how to light, that's gonna be completely up to your personal taste and preference.
So i don't get it . I have a Scene. It's just a scene. YOu said 3DDelight scenes dont' work on iRay. Well it's just a scene. i can switch it to 3DDelight or iray.
Anyways, I managed to be able to render my scene in iRay simply by removing the skydome. I don't understand why the skydome was the cauese of the problem
Here's the picture i made with iRay. It's good except i have a Distant light pointind down at the ground yet i don't see a sunny lighting. why?
The skydome is a "fake" element in 3Delight. It is a physical structure that blocks the light of a real "skydome" in iray, which is not a "fake element", but an actual source within the environment.
(3Delight is open-GL, made for "games", and thus, uses game-terms instead of actual rendering terms. "Sky-box" is a trick created in "Doom" days. Honestly, it isn't even an actual sky-box, which is a projected, static-position and unlocked rotation, element in a "game". It is just an actual box or dome around your scene. Designed by someone who misinterpreted how an actual "sky-box" functions, in open-GL.)
Removing the obstruction "sky-box", allowed the actual light of the iray environment to illuminate the scene.
Ok never mind what i posted before...Now i got it. You change increase the LUMEN instead of the Intensity. :) Great i'm getting it. doing some tests and it looks good
Great!!!!! tip. and advice overall. Now i see that Lumens is what i should change. I did, and now it's brighter
ctrl(Win)/cmd(Mac) L is a toggle for preview Lights - it is on by default, so the first press switches it off (and you get the sceen list as if you were just using the camera headlamp, except it won't render).
Switching render engine switches the light mode - Photometric is useful but not obligatory for Iray lights.
That will vary by surface settings (and shader - a 3Delight shader that does not sue the default property names will not convert well.
3Delght lights can also use inverse square falloff - by deault regular point lights do, spotlghts don't.
Not every 3delight scene will use a modelled skydome - uberEnvironment 1 and 2 don't need one.
3Delight is nothing to do with OpenGL, it's a Renderman-compliant engine with a full set of features (though not all fo them are available through the default shaders). The use of a modelled skydome is a choice of the product creator, for ease of visualisation or because it was more efficient in render time or memory use than the alternative for example.