Friday, July 10, 2015

When you see diffuse inter-reflection

Of course we see diffuse inter-reflection all the time in painted rooms, but mainly it makes them have a big "ambient" more or less, and it's hard to tell what is there.  Games like Mirror's Edge made isolated effects more obvious by cranking up the effect both by model design and by multiplication.  If you want to crank it up in model design, I saw a good real world juxtaposition today about 100 meters apart with the same overall environmental lighting.  

On the left there is surely a big "splash" of indirect light at the base of the container.  But there are several things working against it:
  • The container's albedo is pretty low (I would guess 25%)
  • There is no hue to the container
  • There is almost as much direct lighting hitting the pavement (Sun angle around 30 degrees)
On the right we have another situation that emphasizes the indirect blur:
  • MUCH more direct sunlight hitting the yellow object (Sun directions almost tangent to wall) 
  • Hue contrast of indirect illuminator
  • Indirect illuminator has relatively high albedo (it may in fact be fluorescent)

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