2.5 "Shadows only" are too pale!

Support Compositing and Post Processing
#1

I’ve got a really tight compositing deadline where I need to have a blender model sitting in a “real” (camcorder) environment. The idea is to have the model sitting on a plane which has “alpha shadows” or “shadows only” settings so that this can be overlayed (e.g. alphaover) over the original footage and the model will walk around casting shadows on the ground etc.

The problem is (seen here with a test file) that when I activate “shadows only” on the ground plane, the shadows are really pale. So pale in fact, that if I apply an “alpha over” to to the original shot (to superimpose the model) the shadow pretty much completely disappears.

shadowsonly_problem.jpg642×540 32.1 KB

By my reckoning, the attached sample should have a very black shadow like it does when Only Shadow isn’t activated. That way, it should overlay successfully onto movie footage of its environment. (No, I won’t be having the shadow that black in the final; this is a sample of the problem) Gotta be missing something simple like a sliderbar or something.

:frowning: Please help me on this - I’ve spent far too long on it already, seriously behind etc.

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Attachments

shadow_problem.blend (79.8 KB)

#2

The plane is set to cast shadows from shadow buffer lamps, but you don’t have the lamp casting buffer shadows, check the lamp settings. Then choose something other than inverse square for fall off, like constant maybe?

Personally I think the paler shadows are more realistic than near black. Better to have too light shadows, render to a separate layer and adjust them down darker in post when you grade, than the other way round.

If you have such dark shadows in your video footage, then maybe you shot too contrasty and/or be aware that importing video into blender in most case results in your shadows and highlights getting scaled and intensified in the conversion to RGB making them have more contrast than they were captured on camera.

Or you may say I like the contrasted crushed blacks and blown highlights look. :slight_smile:

#3

Thank you very much for replying.

I’m in the middle of finishing a book on Blender at the moment, and have to do a chapter on compositing, which I’ve been holding back because it’s not my strong point and at this hour I’m not thinking 100% straight so again… thanks very much for your input.


I managed to get a working solution by changing lights in the meantime (see my quick example above). In my tutorial I’m looking at how the legend Weirdhat originally made his composition old-school style (pre-nodes) at http://www.weirdhat.com/blender/compositing2/, and then link this to how the same effects can be achieved with nodes. (I’m just waiting on hearing back from Weirdhat regarding permissions on referencing his idea).

Now that I have looked at your insights; yes, I can see that’s actually more correct than half the stuff I was trying. My first drafts are all (finally) supposed to be finished next week, so it would have been a disaster if I couldn’t get past even the shadow / lighting of this final chapter I’ve been avoiding.

Thanks again.