Real 3D shadows with greenscreen footage in Blender

hello it's Alden this question about Shadows with green screen footage is a really good one because I just ran into this problem and I've been using a combination of three solutions the first one which is the ideal is to create real Shadows with your layers in blender for example if your footage is transparent their feet would be causing Shadows on the floor based on the lighting of your scene if your actor is moving from left to right on the same plane it's pretty simple and you basically just need to intersect your layer slightly with the floor plane but if your actor is moving toward or away from the camera it does get a little bit more complicated but there is a solution the technique I use for that I actually learned from Ian Huber which is probably no surprise to anyone learning blender and it involves parenting the footage to the camera and then animating the scale to get the feet to line up with the floor so here's a shot that I've been working on that involves five people turning this corner and walking down this hallway this hallway is made with 3D scans so everything is entirely CG and four of the Androids following our main character who's played by Nana Visitor from Star Trek Deep Space Nine are the same actress which is partially why we filmed this on green screen so I can do exactly this so let's get started first you want your camera and your footage in the same position and rotation you can select your footage and then select your camera and hit Ctrl C and copy those two properties if hitting Ctrl C or command C doesn't do anything for you you have to activate the add-on then tap into your footage and hit G to move your footage and then z twice and that'll move it along its relative z-axis move it so it's in front of the camera but the origin point is going to stay right where the camera is and then from your camera view scale it down so it matches and from here we're basically going to scale the footage up and down so the feet are always matching the floor so you want to scale it so the bottom of the foot just touches the plane that is the floor if you turn on auto keyframing you can do this super easily this process does take a little time especially if like me you have five individual layers of people turning a corner and walking down the hallway when all of that is done the scale will be moving your layer closer and closer to the camera to mimic that forward movement in 3D space but to your camera itself the footage looks normal it cancels each other out the results are pretty good but you'll notice one big problem it doesn't take into account that both feet are on the floor but in your 2D plane the back foot is higher than the lower foot so you're only getting the Shadow from the front foot the way that I fix that is actually the third technique but first let's look at how you can bring in Shadows for your green screen footage from the green screen footage itself here's an example from a work in progress shot you'll notice that this is a green screenshot and there's a shadow below them again this is still a work in progress so this isn't you know final render but I can show you what I was doing here with the Shadows there are two Shadow layers here One is using the actual green screen footage itself and um and just keying out the green and leaving the shadows and I did that on this layer with composite brush which is a paid plug-in it was a little bit expensive but it does have some very specific use cases that are really helpful and this is one of them so if I turn everything off this is the the shot itself and what I was doing was keying out all of the lighter green areas and I wanted to keep the the Shadows here and you might be saying you know hey Alden if you were shooting this on a green screen shouldn't you have made sure there were no shadows and yes you're right but uh that's not what happened so um consider it a blessing in disguise because this Shadow reference is actually really helpful so it's masked out but I'm going to keep that mask off for now so I used this composite brush where I could select just the lighter green and keep the darker green there and then I just used a fill layer to make it a bit darker I masked that out and then I think that opacity was at like 35 or something like that and that's how I kept the Shadows underneath the key in that shot and the second layer here is some more specific Dark Shadows underneath the feet of the chair because they looked like they were hovering a little bit and they just needed a kind of a dark shadow there just to show that they were sitting on the floor this chair was broken during the shoot so we had an Apple box under it so this whole bottom part is the same thing I took the bottom from this chair just duplicated it over there and then had to add an actual Shadow and now let's go back to the blender shot for the third method which is rotoscoping if you look really closely at this shot uh you're gonna notice a lot of problems with the Shadows but it's going so quickly when it's in motion you don't really notice it so much so essentially what I did is I took a version of the of the footage and took out all of the red because the Shadows were blocking this red back light and only having the green floor so I color corrected the background version version of the footage and then just manually key framed these mats so that when the front foot was causing a real Shadow I was making a fake Shadow for the back feet and some places that looks a little messier than others but again when it goes fast it sells it this one honestly wasn't as big of a pain as I thought it was gonna be there's still some weird flickering things happening with a couple of the layers that I might try to manually fix one thing that you can do to avoid all of this is put a floor down on your green screen shoot during our green screen day we put down blankets on the floor to help with the green spill but if I could do it all over again what I would have done is instead brought in some type of flooring that we could put on camera some type of laminate that looked like it was concrete or tile or a metal grating anything like that now we would have gotten a bunch of green spill on that floor but I think that's something I could accommodate for and end up with realistic Shadows on the floor better than having to manually do all these things but as you know production is what it is and sometimes you just make do with what you have especially when we're doing visual effects hopefully you've found this somewhat helpful if you did let me know in the comments below if this was an atrocious dumpster fire of a tutorial maybe keep that to yourself and be sure to subscribe and turn on notifications if you want more tutorials and definitely ask me if you have any other questions about visual effects about blender about after effects about filmmaking anything that you need to make your film a reality let me know and hopefully can help you out with a with a tutorial [Music]

Channel: Alden Peters

Views: 13,416

Keywords: alden peters, filmmaking, bts, production diary, how to make a film, film youtube, indie filmmaking, vlog, short film, sci-fi, science fiction, lgbt, lgbtq, blender tutorial, green screen, blender vfx, after effects, green screen video, green screen background

Id: mUj1cgX6fyk

Length: 7min 27sec (447 seconds)

Published: Tue Nov 01 2022