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Thread: Green screen invisibility cloak error.

  1. #1

    Default Green screen invisibility cloak error.

    In this video I am trying to create an invisible cloak effect as seen in Harry Potter:

    I'm using a green screen here and have seen other people make the green screen completely invisible, but as you can see from mine, it's still slightly grey / silver. Please help thanks. Also I am using Pinnacle Studio 14.
    Last edited by SovietNinel; 01-19-2011 at 08:46 PM.

  2. #2


    When using a green screen lighting is very important to get a very even colour to key out. You have all sorts of shades which is why you can still see it. Try and get some tights on the clock from different positions so you don't get the shadows. Doing this will make it easier to make the cloak fully disappear.

  3. #3


    Green screen isn't really the ideal way to go about doing this particlar effect, But if this is the type of thing that you'd like to do there is a lot that can learned from experimenting with it.

    To key out the values of a green screen sucessfully requires understanding. If you think of your video being a collecion of pixels of various colours and values of lightness, the simplest (not easiest) way to remove a section of the screen is to make the pixels in that area identical to each other, before telling your computer not to display those valuses of colour and brightness.

    Modern keying tools do give room for variation. But still, the best keys (even on the best of equipment) are pulled from green screens that are as consistent as possible.

    If you look at your video the first thing you will notice is a lack of light. This causes all the colours that exist in your scene to lack in brighness, and have little in variation of values. Our eyes need light, it is the light that reflects from surfaces in different ways that we percieve as different colours.

    It is light that reflects, enters the camera lens and is recorded by the sensor.

    If you look close at your video, you can see that even if the scene was lit to a level that would allow an image to be captured, there is still a problem. The green screen has folds, making it impossible to be lit evenly. It casts shadows on itself.

    If this type of thing interests you, you could experiment with your green screen outside under different daylight conditions. Notice that the diffused light of the sun on a cloudy day gives an even spread and that keeping the screen as flat as possible stops it casting shadows on itself.

    Camera work is all about understanding the light, and shooting for green screen requires an understanding of the camera, this is where you want to begin.


  4. #4


    What is the most ideal way to do it David?

  5. #5


    There's usually more than one way to do anything, and a combination of techniques related to chroma keys, luma keys and basic fades can be combined to create the effect depending on how much time and budget is to be put in.

    With a green screen you need to get a perfect ballance when separating your green screen lighting from your subject lighting. When doing this effect, your green screen and subject interact and become the same thing, so the lighting can't be separated. A technology called Chromatte offers more leniency than a green cloth in this regards, but it's not the magic self lighting green screen alternative that is often assumed, and it is very expencive.

    It is basically a cloth which is covered in thousands of tiny reflective beads. Working in the opposite way to a satalite dish the beads reflect light directly back towards its source. A ring of green LED's is positioned around the lens, and all the beads reflect the light from it directly back, and the cloth appears green on the sensor.

    A cheaper (and possibly more effective) way to reproduce this would be to just use any cloth, then rotoscope the cloth out (draw a mask around it and animate the mask to follow it's motion over time) cutting a hole in your image. You then put the back ground layer in as normal and the invisibilty cloak will appear perfectly clean.

    To make for a nicer effect, adjust the mask transparency to fade it to fully transparent as the cloak goes over the subject and back to fully opaque is it comes off again.

    Shooting some POV footage with your camera under a chiffon type cloth, to cut to and back from, can really sell it.

    Last edited by david walsh; 01-20-2011 at 08:33 PM.

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