I need the shadow pass to contain shadows which are cast by the hdri lighting
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3
3di
18 Dec 2019
3 Comments
t
testure
this is actually a more complicated problem than you might think, image based lighting works because a light's intensity can be derived from high dynamic range- and yes, deriving a shadow's angle is easy enough using this information, but shadow softness is calculated by the size of the light source- which can't be easily determined using nothing but an image (how does blender tell the difference between a light bulb and the sun, for example). There have been a few whitepapers written on this subject, but the result is never very convincing in my opinion- the result is usually pretty uncanny and not well integrated with the background image.
3
3diAuthor
*
@testure
* but the shadow information is already available in the beauty pass, so it must already be calculated no? Not just a case of subtracting the shadows from the physical lights from the diffuse channel (minus reflection etc)?
J
Josephbburg
*
@tibbyninja
* It's not simple, and the shadow catcher has a lot of known problems. It's on the roadmap, but it's not as important as some of the other features (here's the
developer task page
(note that this isn't a good place to ask questions or leave comments, do that
here
)
3 Comments
this is actually a more complicated problem than you might think, image based lighting works because a light's intensity can be derived from high dynamic range- and yes, deriving a shadow's angle is easy enough using this information, but shadow softness is calculated by the size of the light source- which can't be easily determined using nothing but an image (how does blender tell the difference between a light bulb and the sun, for example). There have been a few whitepapers written on this subject, but the result is never very convincing in my opinion- the result is usually pretty uncanny and not well integrated with the background image.
* @testure * but the shadow information is already available in the beauty pass, so it must already be calculated no? Not just a case of subtracting the shadows from the physical lights from the diffuse channel (minus reflection etc)?
* @tibbyninja * It's not simple, and the shadow catcher has a lot of known problems. It's on the roadmap, but it's not as important as some of the other features (here's the developer task page (note that this isn't a good place to ask questions or leave comments, do that here )