Iray lighting for Animation?

Deke

I've had some success with Iray lighting on an animation project. Typically I can get the lighting balanced so there is no blow-outs and yet the scenes render at 1-2 minutes/frame. One shot, however, is a pain: if the distant light through the window is to high (200 lumens in the flux scale) the character's face is blown out. Too little and the face takes forever to render spot-free. Been tinkering with tone mapping all day, but can't find a sweet spot. Any ideas?

ShawnBooth

Can you show us something? Some stills?

Is your headlamp on? 

200 lumens, you're talking maybe a 25W bulb...

Sweet spot (tone mapping)? Completely depends on your scene and lighting.

Tobor

I've not yet verified this fully, but, but under Iray, distant lights seem to render as lumens per cm^2 as measured at the scene. 200 lumens cm^2 is a ton of light. Other lighting is measured by its output, but distant lights are  treated as infinite light sources with parallel rays. So, there's no inverse square law or other attributes common to the spot or point lights.

Shawn makes a good point about the headlamp, though Iray's two settings are Never and When No Scene Lights. As you have a distant light, at least, the camera headlamp shouldn't be active in any case. But make sure by going to the Render settings, click on General, and choose Never for Auto Headlamp. For any user-added cameras, you can also turn the headlamp off in the camera control.

Iray has trouble with main light streaming through a window or doorway. It has an internal lighting helper called light portals, where you can define a window or other shape where light is coming through. It helps the engine know how to use this opening to light the scene. Unfortunately, D|S does not yet support the light portal feature of Iray. You may need to try some other lighting techniques to simulate what you want. For example, you can still use that infinite light, but tweak it down for the scene in general. Then use another light, positioned closer, just on the character.