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Siggraph - Video Compositing


demo-bob kopie.jpgToday we show Bob Holcomb giving a demonstration of video compositing and garbage matting in Blender. Garbage matting is used to occlude material from a video that should not be included in the final edit. Although I'm sure it's pretty common, it was the first time that I saw someone use this technique and I was intrigued by what he showed.

Bob has been involved in Blender development and has written a number of import and export filters for Blender, and lately a number of nodes for Blender's video compositor.

Download: mirror 1 | mirror 2 [Quicktime, 53MB]

Note: right-click and save-as to store the files on your harddisk

About the Author

Avatar image for Bart Veldhuizen
Bart Veldhuizen

I have a LONG history with Blender - I wrote some of the earliest Blender tutorials, worked for Not a Number and helped run the crowdfunding campaign that open sourced Blender (the first one on the internet!). I founded BlenderNation in 2006 and have been editing it every single day since then ;-) I also run the Blender Artists forum and I'm Head of Community at Sketchfab.


  1. Bart, thanks for all the stuff. It's really usefull...

    Is there any opportunity to take this videos right from the screen of PC on which the hole action is taking place... i mean just to record all the tutorials at the same time as the are shown to the public... cause the quality is not really good. so it's hard to make out what's exactly happening at the screen...

  2. @Durden: Siggraph is already over so we have to do with the tapes we've already got. In any way, recording a computer screen on PAL (or NTSC) resolution will result in a slightly better result, but I'm guessing you still won't be able to read the buttons. We'd need a high-resolution grabber for that...

  3. Garbage matting is always done, it is just sheer madness to try get the keyers to properly recognize all the lighting affected hues of even full bluescreen. I usually pull multiple mattes to get all the necessary detail and then combine them to one good mask. One cheap way to get some kind of fringe matte from semi-furry objects without good keyer is to use edge detection and then process it further. I managed to get it to work okayish even with animated focus shot of spider net (but that was is Digital Fusion, though without good keyers).

  4. @Gunnar: true. We tried some but they crashed during the demonstrations and they made the machine slower. Then there's another problem: the video editing software that I use works only up to PAL resolution and it doesn't read Flash files :-/

    Finally, we're trying hard to put a face on this community. With everyone 'hiding' behind nicknames it makes it easy to forget that there are real and passionate people at work. That's why I always include the presenter in the corner of the screen. I could had also focused only on the Blender screen but then it would be 'just' a voice talking, no face attached.

    So: if I decide to go ahead and I'm going to record sessions on the Blender Conference, then I'll be doing it in the same way as now. For me, these are not meant as video tutorials only, but just as much about the people who are involved... (and I'm not even talking about the difficulties of using multiple camera's to do the recording - grabbing time, storage and editing time would all easily double..)

  5. Hi!

    One more time, the Blender guys at Siggraph have done a great job !

    Excellent demo by Bob Holcomb.
    Thanks a lot for this compositing lesson.

    I was afraid by the compositing node when I opened the 2.42a release for the first time, but I like it more and more each time I see a demo or a tutorial, and I have began to play with it with great pleasure!

    Usually, in film making, compositing is a post production process needing several footages to be treated in a video editor.

    In blender, this treatment can be applied BEFORE rendering, and without needing to render separately several layers.

    It is a huge gain of time and I'm sure an improvement of the final quality, because mixing tracks from different sources certainly brings some loss.

    Great !


  6. Hi Bart (& Co), thanks for making this content available to us Blender Freaks.

    I wish you could continue the whole year through posting a video every day. But I suspect you don't have 365 vids lying around, eh? (And I think asking Eugene to make a video every day maybe would be to much too :)

    I'm a little shocked :) that you didn't use Blender to edit your video's? ( I sorta wondered/hoped all demoreels were produced with Blender too :)

    Maybe someday you can give us a video tutorial too: how to create a demo reel using Blender ;)

    Thanks :D

    PS. I sorta missed the dayly Siggraph reports that stopped all of a sudden after day 1 (wich promised day 2). Understandable you were busy with the tuorials and stuff, but the reports sorta stopped sudden. Even a 5 minute update would have been appriciated. But great work nonetheless.

  7. @Logan: we were wondering what kinds of reports to do - day two and three were pretty much the same as the first one so I figured we needed some other kind of content and I switched to the interviews + demo reports. Actually, it would have helped if we had prepared a better plan beforehand. That's definately something that's on my todo list for the Bconf :)

  8. Havn't looked at it yet but I'll grab it soon - just a little question - Is there some kind of road map for what functions and tools are being worked on for the compositor? What more do we have to look forward to?

    Good job


  9. Yo Bart !
    Well sometimes i'm thinking what i can do in return to the blender community.
    So if you would like some assistance with filming at the Bconf; i would like to assist you.
    Besides Blender i like filming also, and offcourse editing...normally i use Pinnacle Studio. That sucks, only one videolayer in that studip 9.4 version. But it works:(
    Going to watch the vid about video compositing in blender and than take another look at the video compositor; cause i really donot know why i don't use that part of Blender more often. I'm living in Haarlem, have (well can borrow) DV -cam; so just let me know!

  10. FYI - I tried playing the quicktime from both mirror 1 & 2 and I get an " error -2048: the file is not a movie file." I'll watch it on google.

  11. "FYI - I tried playing the quicktime from both mirror 1 & 2 and I get an ” error -2048: the file is not a movie file.” I’ll watch it on google."

    Really? Does everyone have this problem?

  12. I have Downloaded the movie from Mirror 1 and played it in VLC player without problem...

    Though, I must say that I have had a problem playing the first movie (and also the others) of the Siggraph with Quicktime player, and following some infos got here, I switched to VLC Player.

    All Siggraph video records seems to be encoded in a mov format not supported by Quicktime Player, and no update can be found on Quicktime site when I leave the software attempt to update or upgrade itself...

    It is weird, but VLC solved the problem for me.


  13. Great video! I was just starting to do a bit of compositing, but I can't get my video to do realtime in the 3D window. I make a plane, put a video as a texture. It renders OK, even with different frames, but I can't see the video in any 3D window.... how did you (they?) get a moving picture texture?

  14. slightly off-topic, but...

    USEFULL !!!

    a camera tracker

    freeware, specifically mentiones max, maya AND BLENDER
    that's enough to give it a go eh ?

    now we can vote for the most the most annoying TV commercials and draw mustaches on their headz.
    or composite yourself into action scenes where the bad guy misses everything he fires at you..
    whatever have fun !

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