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Puppet Kaos - where Kelvin Kao plays with puppets and tell random stories

Editing Trick: How to Make an Object Hover (Garbage Matte)

Last time I did an experiment to make an object hover in the air using an editing trick, specifically, garbage matte. And now I’d like to share how it’s done. This following video roughly shows the raw footage that I started with, the garbage matte process in between, and the final product, with details to follow.


(If you can’t see the embedded video, see it at http://www.youtube.com/watch?v=zcBGuzW2Y9A

Step 1: Get the Raw Footage

garbage_matte_raw.jpgFirst, start by filming an object attached to a stick or string. In this experiment I used a bamboo skewer and Scotch tape. No good reason other than that they happened to be sitting on my desk. garbage_matte_background.jpg Once you have the footage, import it into your video editor that has a garbage matte feature (I use Adobe Premiere Pro). Once you imported the video into the video editor, find a frame of the video that doesn’t have the object (probably at the beginning or end, before the entrance of the object or after the object exits) and export that frame. In Adobe Premiere Pro, this is done by going to File => Export, and then choose to export only a single frame instead of the whole sequence. We are doing this because we would need this empty background for Step 3.

Step 2: Garbage Matte

garbage_matte_zone.jpg
Garbage Matte is a tool that you can use to preserve an area of the picture that you want, and crop out the rest. If you are unfamiliar with it, read about it in more details in my previous posts here and here. In this case, since the object is constantly moving, the matte’s size and position has to be changed constantly as well. This results in a bunch of keyframes in the timeline.
garbage_matte_keyframes.jpg

Step 3: Fill the Background Back In

In Step 2 you are working to isolate the hovering object, but this leaves most of the background empty (black). This is when the empty background we grabbed in Step 1 comes in handy. Simply put that static picture in the layer before the object and matte and we are done with the hovering object project. In several parts of the video, you can see something a little odd looking where the stick originally connected to the object. This could be fixed by being more careful with the positioning of the matte. I just didn’t bother because this was only an experiment.
garbage_matte_done.jpg

The music in the video is Pennsylvania Rose by Kevin MacLeod.

Related posts:

Special Effect Experiment: Hovering Object
Editing Trick: Garbage Matte
Case study: Putting a character in a car with green screen and garbage matte

Comments

  1. Na
    July 9th, 2008 | 10:28 pm

    That’s so cool! I’m going to have to try it eventually…

  2. July 10th, 2008 | 1:24 pm

    Thanks for dropping by! (Eventually, eh? 😉 )

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