DS 4.8 Iray: Why don't photometric lights show up?
rogerjhardy100
Posts: 286
I've tried to follow Val Cameron's videos but when I put the new photomeric lights into a scene that has some lights in already (or HDRI) the new lights I add don't seem to show up. Even with a new scene, I have to turn the luminenscence up to 55000 or so lumens to get any effect. Default is 1500. How much use is that? I must say that Iray is massively counter-intuitive but I'm reluctant to g back to 3Delight.
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Change your units to kcd/m^2 if you want to use smaller numbers. It takes a LOT of lumens to light a scene (often hundreds of thousands to millions).
(EDIT: Sorry, I forgot, photometrics can only use lumens.)
Are you adjusting the Tone mapping settings in Render Settings? The defaults work for outdoors, lit by an HDR dome or Sun/Sky, but not for interiors lit by local lights.
Hi Richard,
Yes, I adjust ISO and light intensity but if, for example, I add the iray sun, it simply doesn't show up in the scene. I can see it but it doesn't light anything. Also the same with photometric lights but that's just due to the low lumens, I think. However, the sun is the sun. I've had it working occasionally but don't know how I did it.
Do you have an actual sky dome model loaded? That will block external lights (dome or Sun/Sky).
Hi Richard, I delete skydomes if I am aware of them. I assume they are all called 'skydome' but one of the other problems with iray render lighting is that they don't show in the contents list so. after a while, I have no idea what's been loaded. Overall, I have to make the observaton that most DAZ content is really user.friendly but anything associated with iray lighting is massively non-intuitive and difficult to use.
you did change the Environment to Dome and Scene?
For me the Photometric lights are easier to use, all you need is to search Google for real world light lumen output and adjust Tone mapping to real world cam settings. But it also helps with adding some extra fill light just like real world cameraman do for interiors. I use a mesh plane or two for that. Big for soft shadows and small for sharper shadows. :)
OK, I just tried something really simple. I loaded an outside scene, 'Back alley', checked there was no skydome. Added a camera then turned the headlight off, added a light and turned the intensity off (all counter-intuitive things to do but ....), added the iray sun, checked 'dome and scene' and did a render. Results: just a normal 'headlight' render with no sun or shadows. What's going wrong? If I load the same scene with an HDRI generic sun, I get the correct effect but there is nothing in the contents list to tell me what I've loaded. It seems that whenever I load a photometric light, it has no effect at all. Help!
Photometric lights are controlled through lumience further down the list. A good starting point is 45.000 units, except for distant lights, which should be tuned down to 10-15 units. (Then, there's that entire Tonemapping stuff, but for the biginning, just cranking up the light will help).
Intensity is for 3Delight lights.
Check out here:
http://www.daz3d.com/forums/viewreply/820983/
I did some light tests during the Beta, but the slider is the same.
Thanks Lee, that worked with 50000 lumens. I wonder why it defaults to 1500....seems designed to create frustration! I can now also get the Iray sun to work but only by selecting 'sun-sky only' under the environment tab in render. The scene still appears in any case so those choices also seem designed to confuse. The dome is selected on and I can get a blue sky. I think we need 'Iray for dummies'!
Well, the 1500 is supposed to be a 100 Watt lightbulb equivalent (or something like that), and you know how far you get with that in the real world in a large dark room...
The wy I understand it, it was suposed to be used in combination with the Tonemapping setetings, kind of like you will change your camera settings when you are indoors. The default tonemapping settings are fine for a bright sunny day outside. So that might give you an idea why the rooms are so dark...
If you remove the HDRI in "Dome and Sky", you will also get the sun settings, and can use that in combination with the scene settings (of course, that isn't doing anything if you are indoors...
"The scene still appears in any case so those choices also seem designed to confuse. " <-- I don't understand that sentence, what do you mean?</p>
Thanks for the helpful reply. When I said I was confused, I mean that the definitions 'dome and scene', 'dome only', sun-sky only' and 'scene only' confusing as the scene appears no matter what. I guess I'll just have to get used to DAZspeak. I have been doing DS for a year now and am having a lot of problems getting predictable results with iray but it's great when I do. I can't help feeling that a real newbie is going to get frustrated.
Ahh...don't worry, I'm at this for two years, and I'm equally treading in quicksand. I agree with you about the newbies - in the German language threads, we try putting together a quick FAQ about Iray.... but it's a pain in the keister researching all the functions when there's no real documentation. On the bright side of things, I've learned a lot through experimenting. :-)
The "scene" refers to the light source being used.
Dome and scene --> uses the lights in the secene, and the dome (usually a HDRI-image, or the sun&sky; settings if you remove the image) as light source.
Dome only --> uses just the dome lights
scene only --> uses just the scene lights
sun&sky; only --> uses just the sun & blue sky as light source.
Danke schön!
Oops, just another point I wanted to clear up. I've just created a simple character and tried photometric lights, which worked as advertised. I then applied an HDRI set of lights and these seem to trump everything else. In other words, if you have an HDRI set in the scene (and it doesn't appear in the contents list) then any other lights you add cannnot be seen, including the iray sun. I my understanding correct?
Well, most depends on what base set you use. If you use "Dome&Scene;", then adding a HDRI will hide the sun setting dials.
The scene will still use whatever scene lights you have in it. But the scene light is fighting against the much brighter HDRI light, so you will often not see much effect from then. It would be different if you were working with a room set, and have the HDRI light shining in from the windows, while using other lights to imitate lamps and such.
HDRI is an image and therefore isn't content. It is also called IBL )Image based Lighting) Look up what a HDRI is with Google.