I was making a project with a live action video interacting with animations. Since the video was taken on a tripod, I skipped tracking and just put the video in the background of the project. I was wondering if there’s any way to cast a shadow on the ground without having an actual object there. Whenever you set up a tracking scene, the floor does just this- it is transparent, but shadows can still be cast on it. I can’t track the file for some reason, so I’m stuck with this problem.
This may “FIX-IT” but may not the easiest resolve as Blender MAY have a solution for this I am unaware of. (Being new to it)
If I understand you want your character to cast a shadow onto your imported video floor?
It looks like you tried to use your video as a background already. I have read that you can export your shadows and really any layer out as it’s own layer. SO I think you can export your “Z” depth shadows and then you could composite them for your final out. No?
Or you can do the ol green screen cheat if that above is not prudent. Where you copy your character, flatten and position the copy to appear like a shadow would via Feather, Opacity and angle, parent it and see how that looks.
For you cannot have shadows on transparency, or you would have a shadow if you were falling at 35000 feet. Not on the Earth but in the sky as the Earth is not Transparent…Yet the sky is
There should be ground in order to shadow fall somewhere. Create ground and project your footage accordingly - from the camera.
If the camera is shaky during the shot you would have to make sure ground plane moves too, yours does not. Check some “shadow catcher” or/and tracking tutorials - this e.g. Sebastian König is one to watch on this subject.
What if you shot your scene with white floor plane and after make white transparent, composit just dark parts over the footage? Just a guesswork…
Usually what is done is to create a Blend file with a plane in the appropriate position, and something of reasonably the right shape that will cast a shadow onto that floor plane. Now, store this Blender output in a “MultiLayer OpenEXR” file, and be sure to capture the “shadow” pass. This, and only this, is the information that you will need: it shows where in the frame the “shadows” appear, and how dense they are. You’ll then use this, isolated from everything else, as a source of input to some combination of nodes that produces “the realistic shadow” that you want, bearing in mind that mostly what the viewer’s eye expects is that “some kind of a shadow is there.” The shadow track is 0.0 = no shadow, 1.0 = totally opaque. You’ll use something like an RGB-generator node, gated and masked by the shadow track, to produce the actual visual information that represents “a shadow of appropriate color” and blends it to-taste within the shot.