In Cycles s it possible to make it so that a light will affect only one particular object? A very simple example would be to have a box on a plane where I would like to have:
a light that illuminates both the box and the plane (making the expected shadows etc), and
a light that illuminates just the box and does not illuminate the plane at all (for highlights on the box etc without diminish the shadows created by the first light).
I know this is not at all physically correct, and risks looking strange if the lights aren’t well placed, but this would be very useful for the visual illusion I’m trying to achieve.
select the box and go to Properties->cube->Relations and make the cube exist in layer 1 and 2
move the light for the cube to layer 2 (make sure it does not exist in layer 1)
Set different render layers for layer 1 (light plane and cube) and layer 2 (light2 and cube)