Learn Green Screen Basics With Blender | VFX Tutorial

green screening is an age-old technique used in filmmaking and is surprisingly easy to pull off inside of blender hey i'm kidding profit and in this video we're going to go over some quick tips and tricks on how to effectively pull a key from a green screen using the tools inside of blender's compositor so i'm going to load in my footage i'm just in the motion tracking section of blender and we're not going to do anything else here we're just going to jump right straight away into the compositor and this is how i've got my compositor set up i'm going to press shift a and you can see blender has a lot of different keying nodes here we're just going to use the one called keen because that gives us the most flexibility and a whole lot of cool settings we'll go over what each of these settings do but for now i want to focus on the garbage and the core mat right here this allows us to plug in a mask into these inputs and remove parts of our footage that we don't want and vice versa key parts that we do want so i'll jump into masking and add a garbage mask name it garbage if i just press shift a i can go ahead and add a square mask and i'm just going to scale this up and position it around the parts of my footage that i definitely want to have removed and i'm just going to scroll through my footage make sure everything stays contained i'll add a new mask name this core control left-click to draw around the inside part of my footage and this is also very much optional but i like doing this because it ensures that the parts of my footage that i definitely want to keep don't get affected by the king of the green screen and i know that if there's a blown out area of my face or the eyes that that's going to make sure and stay nice and clean so back in compositing i'm going to drop in a mask node and pick the garbage mask and if we plug that into the garbage input of the keying node you can see it does the inverse of what we want so let's just throw in an invert node and boom we've got rid of all that extra nothingness that we don't need and i'm going to plug in my core matte and you can see right away we're off to a really good start now all we have to do is worry about this little extra area of green i can use the eyedropper tool to pick that green color and then just adjust it on the color wheel to find the exact shade of green in my green screen and you can see blender's doing a really good job of keying that out i can adjust the brightness of that green find the darker shades by dropping this factor here and there you go that looks pretty good now all we have to do is just dial it in a little bit if we control shift and click we can view the edge of our map the edge kernel basically is what determines what pixel belongs to the innermost edge or the outermost edge so you can adjust that so you have a nice clean thin edge all the way around your mat now there comes a point where it becomes a little bit tricky to figure out what we're viewing here so if i press shift a and drop in an alpha over node and now we're viewing our key over top of a white backdrop i'm going to check convert pre-multiply so now this exposes a lot of the errors that we have in our key and you can see we have a little edge here where our mat isn't exactly pure black and white so i'm going to turn the clip white down a little bit and that takes care of that issue right there if we go ahead and view the mat ctrl shift and click you can see there's an area right over here where we have some bleeding going on so if i just take up the clip black factor that takes care of that now we have a really nice clean mat which is great and we might want to dilate this a little bit i like to do kind of a -2 and then do a little bit of feathering and blurring obviously your footage is going to be different the main thing is that you don't feather or blur too much or it's going to be very obviously fuzzy around the edges of your key so i'm just making sure that my key is pretty good over my whole footage and you can see we've done a really successful key in just a matter of seconds using this keynote really the most important thing here is that you have plenty of light on your green screen whether it's homemade or a professional screen whether you're doing it outdoors or indoors with studio lights you want to make sure that your screen has plenty of light and you provide that nice level of contrast so that blender can easily key it now you can see we can just adjust that background color and we're done and if we want to take it a step further we can drop in an image node or video clip into that top image factor of our alpha over so i'm just going to demonstrate with this city image you can pick whatever backdrop you want so now if i want to integrate these together i of course want to do some light wrapping and that's really kind of the cherry on the top for a successful green screenshot is to integrate them with a light wrap so how do we do this well i'm going to drop in a mix node and right after this alpha over just throw it in there i'm going to mix it with my final output and then with that image only i'm going to throw in a blur node and blur that image a good bit i'll set that image to add so now what we have is a blurred version of our image added over top of our footage i really just want this to be around the edge of my subject so i need to create a light wrap map what i'm going to do is take that output of my mat and plug it into a dilate you wrote node i'll set that to something like -20 and drop in a math node set that to subtract and then take the original output of that matte into the math node and i'll subtract the dilate you row node from the original map it's a little bit confusing but what you should have is a nice clean edge that we can then adjust make it bigger and softer do whatever you need to do to make your light wrap map i'll take that and put it into the factor of that mix node it looks a little too ridiculous right now so i'm going to duplicate this mix node set it to multiply and set that bottom color to pure black black equals a value of zero anything multiplied by zero is zero so now we have a factor slider here that we can slide around and figure out how much of that light wrap you want so now that you can see that our background image that was blurred is mixed with our original footage but it's same constrained to just the edges of our subject you really want to go kind of subtle here just enough of that background bleeding in over top of your footage now of course you want to make any adjustments to your background layer to make it look like the lighting is matching so here i'm just flipping the background image and then using some transform nodes to adjust and transform my footage making sure that the light wrap also follows those same transforms i'm speeding this up because this is really all to taste and all to the background footage that you've used i'm also going to blur my background footage and throw in a bokeh node there so that we get the nice bokeh look and then of course integrate it all together with some color grading and that just makes your shot look like it's all happening in the same area all the light is coming from the same direction and the color values are all the same so there you go that's green screen and blender a few quick tips for you hope this was helpful hope you guys can use it to make some epic green screen shots this has been kin profit for cg cookie thanks for watching you

Channel: CG Cookie

Views: 105,193

Keywords: blender, tutorial, blender tutorial, cg cookie, blender 2.8, blender how to, green screen, keying, green, vfx

Id: i_CiCjuG7y4

Length: 7min 45sec (465 seconds)

Published: Wed Aug 05 2020