Lights with Iray rendering

tracciante

Hi,

I've a problem  with lights when I use the Iray render engine. In the rendered image I get always & only the auto headlamp, despite all the lights I put in the scene. What am I doing wrong?

kitakoredaz

In render setting tab,General>misc, you can set Auto Headlamp as gloval. I usually set as "never" .  it work about perspective view too.(3d view without camera)

then in  camera tab  >head lamp>  "On and off" ,  you can set camera head lamp individually (as local)

about scene lights visiblity, you need to set Render setting tab>Enviroment>Enviroment mode .

it decide which light soruce can emit lay when we render. If you do not hope to use any enviroment light, you may better set it as "scene only".

if you set it as "Dome only," or "sun sky only", DS ignore  scene light , then daz "photometric light",  can not emit light. 

but about "mesh light" which you set emission collor for iray shader of the mesh , it still emit light. 

fastbike1

@tracciante

How about a screen capture of your scene, one of your scene ta, and one of your render settings tab so we can see what you have.

tracciante

Hi,

thank you for answers.

In render settings I set Auto Headlamp "never" and Environment Mode "scene only"; in camera settings, Headlamp Mode "Off"; in lights settings, Illumination "On" and Photometric Mode "On". But the Iray render engine keeps on ignoring my scene lights (with 3Delight engine the scene lights are rendered  without any problem). I really can't understand what's wrong.

tracciante

I tried again and now I see that the Iray render works fine with the above mentioned settings, even if the image is much less bright than 3Delight (it's matter to adjust the lights intensity).

Thank you again.

kitakoredaz

Yes daz iray ldefault setting Luminance  value usually dark, when we compare with 3delight , if we do not use  enviloment light. 

if you use mesh light with iray shader (as same as Uber area light),  you can change unit, cd/m*2  to cd/cm*2   etc.   but daz default photometric lights can not change unit.  

I often  set luminous flex value of daz lights,  as high, 20000 or 30000 etc

But maybe for photo realistic, With keep range of luminous flex,   set tone mapping in render setting tab, then adjust each proeprty as same as degital camera (auto adjust exposure), or manually change Shutter spped and F stop.  

Eagle99

Here are some quick tutorials about Iray lighting:

and Render settings:

They covers some of the basics. You can find a lot of Iray and DAZ related tutorials on youtube.

Most important as mentioned before: increase Luminance

Don't be shy.... for a sunlight far away from the scene it can be millions. The default value is a little candle maybe.

Also the type of light is important. To get softer shadows, i.e. you can use a Disc as Light Geometry and dial up the Height to 30 or more for a closer one or a few hundreds for a sun. As it's all physical based, there are no shadow settings. They depend on the lights you are using.

 

You can use the default render settings as a starting point to get an idea how the lights work.

Make shure to select "Scene only" in the render settings to test your scenelights one by one.

Later you can experiment with common rules for photography like this: https://en.wikipedia.org/wiki/Sunny_16_rule in the render settings, depending on your scene of course.

 

I was expierincing the same when I started with Iray, thinking, damn, why the don't work...

 

Kind regards, Eagle99