Rendering with changing lighting conditions


#1

Bright indoor lighting, then lights in the scene turn off, and the illumination comes from outdoors. Very low light, with sharp metalic reflections. The intent is to have a good exposure in both cases. What approach would you take?

Two exposure settings on the camera? Or adjust the exposure in post? What would happen in practical film in a case like this?


#2

Hello,

In film the camera exposure while recording can only be modified adjusting smoothly the aperture of the diaphragm. The shutter speed has to be 180º (double the frame rate) to have correct motion blur and avoid light flickering, so this can´t be modified. And the sensitivity of the film of sensor can´t be adjusted live. Increasing the Neutral Density filter can also be an option but it won´t have a smooth change in exposure as with the diaphragm

Since in 3D there is no real diaphragm nor lens, you will have to fake the change of exposure with alternate methods. A change from an interior to an exterior scene may be posible with the dynamic range of 32bit image. So doing it in post-production could be an option. If the contrast of lighting is too drastic a different approach could be animating the “exposure” setting of the 3D camera, many 3D renderers have this option (arnold, vray). Or if this option is missing, animate the exposure of the lights until you get the desired effect, focusing on art direction rather than on physical qualities of the light.


#3

Thanks, that is very helpful.