Iray, casting light
kaotkbliss
Posts: 2,914
I'm having some trouble. I can get signs and lampposts etc. to glow, but they are not casting their light on objects around them. I set the color and luminescence but what do I need to change to get the light to light up an area?
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Check and make sure that your environment (in render settings) is set to dome and scene if your doing an outside render with photometric lights. Also what sort of settings do you have in tone mapping? If your shooting a night scene (my guess if there are street lights) you will need to make some adjustments. You could try and EV between 12 and 15 or change the IOS film setting to 400 to start.
The scene is a daytime outdoor scene with the sunlight on a skydome, by the particular are of the scene is surrounded by tall buildings blocking most of the sunlight. There are various neon lights, windows and light poles that I set to cast light to try and lighten up the dark area which I went into the materials and set the color and luminescence there.
I tried lumen at 50,000 but that washed out the signs and still didn't cast any colored light onto the objects around them so I lowered the lumen to 10,000 so it didn't turn the sign into a big red circle you couldn't read, figuring there's another setting somewhere for falloff or something.
So it seems IOS is similar to gamma as increasing the value lightens up the whole scene. 400 was too much so I lowered it to 200 which looks pretty good, but didn't do anything for the objects casting light. I left all the render settings at default (except pointing the sun to use the skydome and changing the IOS to 200)
The lights from windows and lamp posts are all set to a Lumin of 50,000 and all the neon is set to a Lumin of 10,000
You can see what I'm trying to explain here:
http://www.daz3d.com/forums/discussion/53325/P120/
I can finally set up a scene to try and test this for you.. How do you have the sunlight set up? Is it a light your calling the sun or is it the sun from Iray?
I have a sky dome (from the dystopia city blocks) that I applied the Iray shader to and set it's lumin to 100k or 150k (something like that) then in the iray render settings I set the SS sun node to point to the skydome.
as for the neon's which I would think should be casting colored light onto nearby objects, I simply applied the iray shader to them, set the lumen to 50k at first, then down to 10k and set the emission color.
In environment (render settings) do you have it set to Dome and scene or just dome?
Dome and scene
It isn't that easy fix then. I think I read somewhere that photometrics would not work with just the dome used. And I am having wretched luck with the scene I though I could use as a test. It is one of the big stonemason sets and it may just be more than my computer can deal with. Keeps stalling when I stop the render. I will have to restart studio and try a different angle on it
I may have it. I could not get the emitters to work at all until I added a photometric spot to the scene. If you don't have one of those you can add one and set it at a super low level and see if that turns on your emitters.
I have 1 photometric spotlight I used in that scene to light up the dark street a little.
I'm testing different settings just using the Urban future 1 prop as it's got a lot of neon in it so it will be quick to test with.
Well sadly that was my last guess on why your not getting better results. I'm sorry I have been not much help on this.
There's got to be a way. I'll keep playing around and if I find it I'll be sure to post it. In the meantime, hopefully if someone knows or figures it out they will post here.
Try rendering without any dome or sun - do the lights work then?
In the test scene I left the skydome out as I am just concentrating on finding the sliders that would affect color glow (basically like ambient where a green object will cast green light on objects near it) but I have yet to find said slider :(
I will try re-rendering the original scene without a skydome (I've been wanting to re-render it as it reached 2hrs before I had a clear image)
The scene is still rendering but I did remove the skydome and set the sun node to "none" (I think the overall sunlight looks better now). But sadly, I'm still not getting the "ambient" glow off the neon signs :(
I found SickleYield's plain-English descriptions of a bunch of the settings here
http://sickleyield.deviantart.com/journal/Iray-Surfaces-And-What-They-Mean-519346747
and also took a look through the Daz documents here
http://docs.daz3d.com/doku.php/public/software/dazstudio/4/referenceguide/interface/panes/surfaces/shaders/iray_uber_shader/shader_general_concepts/start#general_concepts
and I don't see anything about ambient type lighting so either the color of the light is not reflecting onto other surfaces as it should, my settings aren't high enough for it to be seen on other surfaces, or since Iray is still in beta maybe it hasn't been added yet.
I suppose my next test will be to crank up the lumin on the neons to ridiculous levels and see if I get any colored light at all on nearby objects. If I do, I'll have to figure out how to keep that setting without the sign getting washed out and looking like just a big red blob.
Are you just using the Ambient in the non-Iray shader then? Have you tried applying the Iray Uber shader, using the Emissive preset?
No, I applied the iray shader to everything in the scene, then set the emissions for the signs and lights I wanted to glow. I just used the word ambient to try and accurately describe the effect I'm trying to get with those lights.
Funny thing I just thought of (and I'll have to go back and check what settings I used)
The very first thing I tried to do with Iray, was to recreate this render
http://www.daz3d.com/forums/index.php?&ACT=50&fid=506&aid=159402_8I77o6hqsiVTw1d4qbty&board_id=1
Did the same thing, applied the iray shader to everything, then set the leaves on the ivy to emit light and there was a bit of green from the ivy on the dragon's wing like in that image, only not nearly as much.
I don't think I did anything different so I'm not sure why it was working there and not in this new render or the tests with just the Urban Future 1 model...
Well now I feel silly :(
I decided to try again and this time I was zooming in and changing angles and found that the color was in fact being cast onto nearby walls and such, just not as intense and apparent as with the ambient lights in 3Delight. So from the distance the camera was from the neons, you can't see the color shining on other objects.
I wish I could intensify the color without making the light source so bright the details are all washed out.
kaotkbliss,
Did you add your diffuse textures to the emission image slot?
LOL I don't even remember.
This was back when Iray first came out and no one really knew how to use it yet. In fact, I'm not even sure if there was an option to place a texture in the emmission at that time.
In order for light emissive surfaces to cast light in IRAY it seems that luminance needs to be around 1 million units in the surfaces setting. After that it seems to depend on the surface area of the object on which the shader is applied. Sometimes small tube (like those that make up a neon sign) don't actually have that much surface area - then it's time to switch the luminence units from cd/m^2 to kcd/m^2 - I discovered this by experimentation when an emissive shader applied to a large complex snowflake shape failed to illuminate when copied to some small short cylinders in the same scene; even doubling the luminence to 2.4 million didn't work, but changing the luminence units to kcd/m^2 and reducing luminence back down to 1.2 million gave the desired effect. My only problem is that the color is florescing up into hot pink from the deep purple applied to the shaders: