Methods for lights in Iray

n.drju_6d88cb4c15

I hate to ask the question and fear the answer but...

Do you have to use an environment map (or 'dome' of some sort) in order to be able to add ligthing when in Iray mode?  How can you possibly control it if it's based on an image?! 

JimmyC_2009

You don't have to use an Environment map at all, you can set that option to 'None'   When you create a light from the Create menu, if you have Iray selected as the Render Engine, then it will be a Photometric Light, and usable with Iray.

In the Environment tab, you can set Environment Mode to 'Scene Only' and several other options.   There are threads on the forums here which will give you a better idea of how to use Iray, there can be a lot to it.

Have a look at this thread by Cris Palomino : http://www.daz3d.com/forums/discussion/56788/iray-start-here#latest

n.drju_6d88cb4c15

Well, thank goodness! I didn't want to buy a spherical camera just for the purpose. 

So correct me if I'm wrong - all I have to do is to switch to "NVIDIA Iray" in the "Render" section and then all light types (newly added in the scene) will adapt for this renderer?

Note to self: Should I mention that my first Iray render turned out pitch-black? Oops... I think I said that out loud! 

Richard Haseltine

Even existing lights (but not 3Delight mesh lights) will become Iray lights, and vice-versa on switching to 3delight. Note, however, that not all settings are translated so you will need to make adjustments for the new engine. Also remember that in Iray the default Tone Mapping settings are for a well-lit outdoor scene, an indoor scene (or any scene lit by local, realistically bright, lights) will need the exposure settings adjusted.

n.drju_6d88cb4c15

I'm not sure what mesh lights are... "Spotlight" type perhaps?

Well, I had the Uber Environment and a distant light. Upon switching to Iray my scene went black in the render, so I guess they did not switch automatically.  Right now I am just playing to Iray a previously made scene which is set in broad daylight, so I think that shouldn't be too tough...

SpottedKitty

n.drju_6d88cb4c15 said:

Well, I had the Uber Environment and a distant light. Upon switching to Iray my scene went black in the render, so I guess they did not switch automatically.

Uber lights are only for the 3Delight renderer, they won't translate into anything that works in Iray. The distant light might have translated too dim to show up; remember the default settings are for a bright sunny day. Go into the Render Settings tab, and you can adjust the camera exposure settings in the Tone Mapping section.

One not immediately obvious gotcha in the light brightness settings — the Intensity dial works in 3Delight, the Luminous Flux dial works in Iray. The other way round doesn't work.

n.drju_6d88cb4c15

I tried to rework some lights and made a test scene with just one distant light present. I applied the Iray Uber Surface Base (or whatever, you know what I have in mind) to my character and moved on.

In the first test, my character (for a change) turned out almost entirely white.  So I cranked down the lumen and temperature settings to around 150, 1500 respectively. Another test turned out quite good actually. However, the light on my character looked more like a sunset light and not clear day. I think it's the temperature setting that should yet be adjusted?

EDIT: I just read about color temperatures so that's probably what I'm looking for but I'd like you to confirm if I'm right. 

Fishtales

Reading these might help, or further confuse 

https://en.wikipedia.org/wiki/Color_temperature

https://en.wikipedia.org/wiki/Luminous_efficacy

http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/lightsources/relationship.asp

http://planetpixelemporium.com/tutorialpages/light.html

http://photographyguide99.blogspot.co.uk/2012/10/the-color-temperature-of-light.html

http://www.daz3d.com/forums/discussion/comment/877156/#Comment_877156

 

KA1

6500 is "daylight" temperature, lower warms the colour towards red/orange higher cools to blue - however, if you've found the lighting set up you have to be spot on you can just adjust the white point to offset the temperature colouring.

KA1

Here's a kind of rough reference - there's a fair few you can find with more details etc if you Google light temperature. 

n.drju_6d88cb4c15

@ Fishtales - Actually they help. Thank you. I just read those on Wikipedia before you wrote.

@ KA1 - Do you have that chart in a bigger version? This is wee too small to use later on.

Tobor

Unless you're trying to replicate a real-world light, you don't really need to worry about the color temperature. Just dial it to zero. When you do that, the color of your light is only affected by its emission color. It also simplifies the processing a bit (rendering might be a little faster, depending on the light source and scene), since it removes the math involved in calculating the color temperature of a blackbody radiator. 

Knittingmommy

Richard Haseltine said:

Even existing lights (but not 3Delight mesh lights) will become Iray lights, and vice-versa on switching to 3delight. Note, however, that not all settings are translated so you will need to make adjustments for the new engine. Also remember that in Iray the default Tone Mapping settings are for a well-lit outdoor scene, an indoor scene (or any scene lit by local, realistically bright, lights) will need the exposure settings adjusted.

I wish I had know this earlier.  I've been setting up scenes in both (saving each as their own separate files).  I've basically been setting up my scene, save it in 3Delight then hit it with Iray Uber and fiddling with the settings.  But the first thing I have been doing after converting the surfaces to Iray is scrapping all of the 3Delight lights and starting from scratch.  I never once even thought to try rendering with my current light setup to see how it looked because I thought they were still all 3Delight lights and wouldn't work.  You just saved me a ton of work!!!

KA1

 

Tobor said:

Unless you're trying to replicate a real-world light, you don't really need to worry about the color temperature. Just dial it to zero. When you do that, the color of your light is only affected by its emission color. It also simplifies the processing a bit (rendering might be a little faster, depending on the light source and scene), since it removes the math involved in calculating the color temperature of a blackbody radiator. 

I've been zeroing it for emissive screens/background pictures but it never occurred to me to zero like this! Nice tip, thank you Tobor.