Wild Tricks for Greenscreen in Blender

okay part two of me trying to explain how to make a shot like this in in free open source software blender and uh today is green screening here we go so i'll have a proper tutorial on how to key green screens in blender at the end here because look okay in the compositor just stick a key node between the movie clip and the composite and click on the green oh and convert pre-multiply to make it actually look good and if it doesn't you probably didn't like your green screen good but i want to start with the fun stuff because there's a bazillion green screen tutorials already out there so how to place pre-keyed people in your scene so hit f3 type in import images as planes find your footage select emission and there you go if you don't have images as planes already activated open the preferences activate it in the add-ons tab and then maybe save preferences to keep it on by default so i don't have to say this every time now you can line up the feet and yeah i've i've gotten a haircut since then but you have natural shadows reflections occlusions you can you can even animate the camera a little bit until the subject walks away from the camera and then things get weird nothing lines up anymore and that makes sense because as far as the footage is concerned as they go into the distance they're just rising up and shrinking and animating the camera blows the whole illusion so you can just have your person stay stationary and it can be as simple as that or you can set up two reference empties and try to animate the footage so it cancels out the person's motion parent it to another you try to match up the person's original motion that's annoying and not good and don't do that instead i i recently did a motion tracking tutorial link links below so let's build off of that first off if you track footage apply that motion to a camera then parent that footage to the front of the camera it stabilizes the footage because the footage motion cancels out the camera motion because i mean if you think about it of course it would in fact okay so this is a tangent but remember the point cloud we got from the motion tracking tutorial model some geometry based on that so it just intersects the reference points now it'll line up with the footage but this is still just a camera overlay wouldn't it be cool to actually stick that footage to the geometry give the object a new material give it an emissive surface and make the base color an image texture just loading your footage set the vector to window that'll make it fill the camera view oh and don't forget to give it enough frames and turn on auto refresh now it projects right onto the geometry as long as you're in the camera view it always projects from wherever you are that's kind of weird we want it to stick so just use a uv project modifier using a uv map and the camera now if you go back to materials and use uv instead of window it'll project the footage from the coordinates of the camera although you might have to change the modifier scale to match your footage a little bit and subdivide the object but now it's stuck to the geometry even if your footage was handheld now it's normalized you can add a second camera and animate some new camera movement uh obviously works best if you stay close to the position of the original camera but this can be super useful technique you can digitally extend out your tiny practical set put in a big crane move that'd be impossible to film in your garage this is this is one of my favorite things because it really lets you rework almost every aspect of a shot in post it makes compositing easier too because you're not just dealing with 2d layers of 3d life it's actually there in 3d space which is a lot easier for for my brain to wrap around oh and since it's an emissive texture radiating light if you have an object in there the texture will actually light the object with directional accuracy within reason what that also means is if you shot your footage handheld you track it and mount the footage to the front of the camera your person will be stationary he's still the same issue as before though if they walk away they'll shrink up into the air so here's what we do select the footage then shift click on the camera hit control p to parent the footage to the camera then ctrl c copy both the location and the rotation you might have to activate the copy attributes add-on if you haven't already it's a very good add-on now tab in it edit mode hit gzz to slide the plane out along its local z axis go into the camera view and scale it to fit the frame perfectly now since the origin is on the camera when you scale the footage it gets bigger and further away in a way that perfectly cancels itself out from the camera's point of view cool huh so what do we do with this well scale it up and down so the front of the foot is just almost clipping into the ground turn on auto keyframing go a few frames later and uh and scale it again do the whole shot this process goes pretty quick if you can't see their feet give it your best guess it's really forgiving and because of trigonometry or something like that the scaling is actually normalized and you have your person walking around the way they actually were on set in fact look at this this is from the dynamo dream teaser and because of this process you can see the footage not only automatically scales to cancel out her size difference as she walks away it also correctly places her in the right place in the scene crazy just from lining up the feet once you start 3d tracking everything just clicks into place that's a lie a lot of things don't but this this thing did so so let's start laying out the environment i'm going to start with some walkways intersecting those tracking markers everywhere she goes maybe maybe blocking some future buildings this is keying not modeling so we're going to go fast and loose and uh let's cheat a little so at one point caitlyn stops and backs up a few steps in the digital environment i have this happen right after she walks behind a wall and i can just add a couple key frames to the camera to make it continue moving forwards as she walks backwards when she pops back out we can use that same bit of green screen again so we have it feel like she's exploring a larger space it's it's cheap but it's fun or oh okay at one point i have her kind of rotating in place on her heel i'm going to add an empty right under her feet parent the camera to it and okay so constraints can get funky so i'm going to convert it to an f curve here now it's actual animation data instead of a constraint and now it lets you parent the camera to the empty and keyframe it at the start of her turn rotate the camera add another to the end and now it looks like she's staying still but the camera's moving just just a fun trick if you want we could parent that empty to a platform and now she's on an elevator this is also a great time to start matching up the lighting you can see she passes a light source here so i'm going to add a digital light to the scene to help integrate her a bit if you figure this out ahead of time you can have digital objects casting actual light on your actors eevee also makes it really easy to match lighting color and intensity random tip if you're setting up lights and stuff in eevee and notice your footage is casting big shadows go into the material settings and change shadow to alpha hash and it works a lot better now so a very exciting thing is that this process gives you a ton of freedom to tweak the camera if you want i like shooting a bit wide so i can more easily line up the actor's feet with the floor and then zooming in a bit with the virtual camera or add a whole new camera flying around while the original is still doing its thing obviously you have to stay in front of the footage you can tell it's 2d but it's more forgiving than i expected what i usually end up doing is just parenting a new camera to the tracked camera so i get all the existing camera movement but i can also still look around and tweak the camera however i like well okay ian you say with the voice of an old man who seemed more than we can ever dream how do you get this green-screened element super easily open a compositing workspace reusing nodes add a movie clip and loading your footage ignore the render layers we're going to connect straight to the composite the composite knows the final node it's what will be saved when we hit render if you control shift click on a node it pops up a viewer node that shows us what we're doing v and alt v zoom in and out and the alt plus scroll wheel lets you pan it's not very intuitive but you get used to it under matte add a keying node and slide it on in there you'll have to update the viewing node to see what you're doing in it and this is the big green screen bit select some mid to darker green now just slide up the clip black to get rid of stuff you want to get rid of and slide down clip white to preserve stuff you want to keep ideally you want to keep these numbers as close to default as possible doesn't look good let's add some sauce add an alpha convert note hey hey sometimes that's all you need but often you'll have to tighten things up by eroding the mat a couple of pixels to get rid of like that fringe and this is usually enough for me but you can tweak all the other stuff screen balance and d spill balance can be great to tweak and a negative feather distance can sometimes help if you have a really messy key just try not to overdo it i don't know what kernels do if you slide something in direction it looks better do it but okay but what about all this stuff around the borders we we have to mask it out which is also easy open a new masking workspace uh loading your footage and control click to add a mask circle your subject and click toggle cyclic to close it you've just created a mask with control handles and you can move them just like anything else in blender hit a to select them all or b to box select g to grab arch rotate s scale all that good stuff hit i to add a keyframe then go a few frames later move the mask and hit i to add another keep going surrounding your actor it doesn't have to be perfect you're just trying to isolate the actor from all that other garbage hit alt s and you can control the feathering if you want under mask display you can turn on overlay to see what it'll look like if you want to add another mask be sure you add it to a new mask layer you can even make them negative oh yeah also okay if you hit tab you're in the tracker what can you just control click on a distinctive point track it tap back to masking select points you want to attach and hit control p to pair them to the tracker yes try to do that in after effects no i oh no i know you can it's just slightly easier here i didn't mean to please now jump back into the compositor and add a mask node using our mask and drag it into the garbage matte input if it appears off make sure your project resolution matches that of the footage this is important also they assume you're rotoring out the garbage instead of what you want to keep so use an invert node to flip it all around and there we go looks gorgeous now we export it the trick is picking the right format since we're pre-keying this we need a format with an alpha channel included that's that's transparency data i'm not an expert but i did try every combination i could think of and uh uncompressed tiffs gave me the best frames per second what i recommend is using two versions one full res and another like one third resolution so your viewport doesn't get bogged down when it's time to do the final render just replace the textures with the full res version and it's all good oh and i should have mentioned this earlier but if you're importing an image sequence just select all the images and make sure anime image sequence is checked there you go so i i hope this is useful there's a ton of other stuff that can be said about lighting green screens and all that but mostly it comes down to making sure you have enough light and the screen is lit as flat and evenly as possible i'm just always really excited about the possibilities of of technology like this and what it can do for like indie filmmakers huge huge thanks to the folks over on the patreon lots going on over there lots of tutorials i've got a video going through the entire making of this shot and lots of assets you can use rigged photo skin dudes plants rocks burger textures like waterfalls steam fire rain all that it's been we've been nuts it's been really good um so yeah thanks for watching

Channel: IanHubert

Views: 1,046,811

Rating: 4.9751277 out of 5

Keywords:

Id: RxD6H3ri8RI

Length: 9min 50sec (590 seconds)

Published: Mon Jul 27 2020

Reddit Comments

[u/PrimoSupremeX]

Wow, even for a 10 minute tutorial you manage to make it feel so to-the-point and keep a good pace. Love it!

[u/Init_4_the_downvotes]

son of a bitch im in.

Can someone explain the tracker joke towards the end? What does parenting the location data to the tracker do?

[u/DarkuiDeville]

wow Ian, genius as always. Keep sharing.

[u/RomanGabe]

Wait. Ian, is that your Reddit account?

[u/Epicduck_]

This is oddly inspiring. Im going to try something out like this later.

[u/Alkanphel]

Obsessed with your aesthetic.

[u/Carsonmonkey]

Damn you make it look so easy. But seriously, your tutorials are what’s keeping me motivated to learn blender.

[u/Euripidaristophanist]

Coming from a technical 3d background, it's really inspiring and encouraging seeing your quick and slapdash approach in your lazy tutorials.
It's been liberating, really. So, thanks!

[u/iCTMSBICFYBitch]

This is incredible. I didn't come to blender for movie editing, but I'll be damned if I'm not trying to figure out where to get my hands on several.meters of green cloth now!