Greenscreen effect without greenscreen

im looking to find a way to have a greenscreen effect without actually greenscreen.

Basically everything is already recorded but there isn't a greenscreen. As if for now, the only solution i can think of is dividing each from into pictures and masking every frame individually. My question is, is there any better/easier/more efficient way to do it? 

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  • Triem23Triem23 Moderator

    So, tracing/masking out an actor from a background plate is called "rotoscoping," or "roto," for short.

    There are a few alternatives. Since you've already shot your footage, some of this will be for future reference. 

    First, get a greenscreen. Preferably one of the reversible ones with a blue side. The bottom line is keying a chroma screen will be faster and easier than any other method and will usually give better results, unless you're a damn good roto artist. 

    Now... IF you were lucky enough to capture footage matching what you need to extract without your actor in frame (a "clean plate," or "cleanplate") you can use something called a "Difference Key." To set this up you need your clean plate in your timeline. You need clean plate running for every frame you need to extract. On your actor's layer add the Difference Key filter, and select the clean plate as the Source Layer. Then you'll have to play with the parameters. The Difference Key will attempt to extract anything "different" from the clean plate. In theory, this is your actor.

    Difference Keys don't usually work very well. At all. For sake of argument, lets say you have a nice blue sky behind your actor and your actor is wearing a blue denim jacket. Ok, that's blue against blue... There's not a lot of difference between two shades of blue, so you'd have real problems trying to get a usable difference key.

    Perhaps your actor is in bright colors against a dark background, or light colors against a dark background. Well, you could try the Luminance Key, which makes a key based on brightness values. If you didn't plan your shoot for Luma Keying this probably won't work well either. Luma Keys work best on a pure black or white background and the scene needs to be lit correctly. For example if keying a dark background you just can't have dark shadows on the actor.

    So... Masking... The good news is you don't have to split your video into still frames. You can just use the masking tools in Hitfilm and animate the mask.

    In this case you want to do "paper doll" animation.

    https://i.pinimg.com/236x/71/4f/fb/714ffb973edb72806c7e8ba023ec7bd4--dancing-dolls-paper-puppets.jpg

    See how the paper dolls in the image above are jointed in sections? This is how you want to approach roto. You roto the torso as its own mask. The head is its own mask, as are upper and lower arms/legs, and hands feet. Yes, that's a lot of masks, but it's actually easier and faster to roto in pieces rather than the entire body in one spline.

    Oh... Maybe your actor moves a lot. Well, instead of having to constantly move the splines, instead, track your actor, then create a white plane (make it larger than the comp size) and parent it to the track. Put this above your actor and lower the opacity to see what you're doing. Now, do your roto masks on the plane. The tracking pulls the plane along with the actor reducing the shifting of points. Once the roto is done you'll need to create a black plan and move the black plane to the very bottom of the layer stack. Place your white roto plane above the black plane,  and put a grade layer right above the roto plane. Then, add the Set Matte effect to your actor's video. Use the GRADE LAYER as the Source Layer, set the Matte Type to Luminance and the Blend Mode to Replace.

    Your last, and probably best option is to buy the Mocha Hitfilm add-on pack. Mocha is a tool specifically designed for roto work and 3D camera solving. Mocha will cut your roto time by at least 50% if not 75%. YouTube has plenty of tutorials on using Mocha for roto.

    This video has more information on keying and masking. Not roto, specifically, and no mocha, but will show a lot of techniques and cover a lot of conceptual information.

    https://youtu.be/9I5VBZwPllM

  • @BobDiMarzio The HitFilm community has tutorials for everything! :)

    https://youtu.be/oY2zMojI1XM

  • @HitfilmSensei  Excellent tutorial.    When I first got mine I wanted to see what it looked like in person so  I unzipped the bag pulled it out and it went boing!  I went oh no, what now  If anyone was watching  first time I folded one they would still be laughing.     

  • @BobDiMarzio That's what happened to me! I looked all over for a good, quick tutorial on how to fold it back up. Unfortunately, I couldn't find a quick one, so I finally watched a super long tutorial, then I made the quick one myself! :)

  • @BobDiMarzio @HitfilmSensei  Guess I'm just a relic from a bygone age.  My screen is just a 9x12 green cloth and folds just like a sheet.    Granted it can take two people cause 9 or 12 ft is long for one set of arms.

  • @tddavis I got a green screen sheet and a blue screen sheet, and that is it, they are big, as long as they work! :)

  • I have a green screen sheet as well.  I love it!

  • Triem23Triem23 Moderator

    I have an 8x18 sheet if I need a big shot and a 5x7 pop out that I use a lot more.... 

  • Me three, but since it's almost always just me, the 5x7 takes almost no time to set up while the sheet with stands cross piece and sand bags. requires a lot more work.  That goes double if I plan on shooting outdoors.

     

  • I'll chip in here. So my little girl had homework that required from creativity, we decided to take some little toy figures and place them against my basic green screen blanket, then take them into Hitfilm key them out and place them on another background of choice. The only trouble was I didn't bother with hanging or lighting my screen and so it didn't work so well. It needed my lights to really help separate the foreground and background. In the end we scrapped the idea and did something else, mainly because it was time consuming setting up the rig and testing. So my advance is whatever you use make sure it is easy to setup and use. 

  • Setting up the green screen is time consuming. I also used to spend time ironing, water-spraying, hair-drying etc my green screen. Since I bought an inexpensive pair of lights and the Green Screener app I've not had to do any of that again. I did use green tape to hang my screen once rather than get the frames out. Worked really well until I pulled half the paint off the walls when I took it down.

    Wouldn't it be nice to have a green room 

     

  • My green screen is always set up in my workshop, which is nice,but I know that not everybody has that.

  • @tonyg  Be still my heart!  I have long dreamed of just that.  Even got the paint all picked out at Wal-Mart; their Kelly Green is a perfect match to my cloth.  Went through a phase of designing houses I'll never build and I put just such a room in each one.  If only...

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