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2D Motion Tracking - Zit Removal

21

tute-image

Dave Weese uses the motion tracker in combination with the compositor to clean up some video footage.

Dave Weese writes:

Hi guys - just a real world example of a shot in a feature film where I needed to digitally remove a zit from the actresses forehead. I'm posting this because there are lots of demos and tutes relating to complex 3D scene reconstruction and all the rest, but very little about the kind of braindead 2D tracking / comps I find myself doing all the time in the course of trying to churn out a made-for-TV movie.

BTW in the video, because of hte lamo screen cap software I use, you can;t actually see the zit very well! Trust me - it's there!

21 Comments

  1. this is useful but it always kinda irks me that people in the "image" industry makes a big deal about a single sometimes pretty unnoticeable blemish...............in fact airbrushin takes alot of um "naturalness" out of these things

      • haha yeah well if prospective employers are going to deny her work for a tiny act of nature that should have little bearing on her overall performance and general appearance "in my humble opinion" <--- compliment :) then all power to her,......still much ado about not much IMO..............but great work by you though

  2. Dave, As for importing .png images with transparency and having the transparency properly enabled for compositing... use the "import images as planes" addon and be sure to select "premultiply" and "shadeless" when you import.  The addon creates a plane in your scene with all of the UV mapping AND alpha channel enabled.  In fact, you can even see your texture by selecting the texture view mode in the 3D viewport.  No more UV mapping... and no more alpha channel settings!

    Thanks for the 2d tracking tutorial.  I have been wondering how to do this for a long time!

    •  Thanks! That worked perfectly. I was using the IIAP add on early in the process and figured the issue had something to do with premul somewhere in the chain between the 3D view and the compositor. I had not noticed those import options, in too much of a hurry I guess.

  3. Thanks for the tutorial - BUT - wouldn't that have been a lot easier with the Mask tool in Sony Vegas?  You might have had to do a little bit more manual work, but you will probably find that overall it would take less time.

    I do however see the value in this tutorial for longer sequences though ;)

    • actually yes and no. The masked blur area technique is pretty forgiving tracking wise and I had another shot where I did exactly that - did the whole thing in Vegas - and it was very quick. In this case I wanted to test the blender tracker so I kind of suffered through it on purpose. Now that I have a cookie cutter solution, blender will be faster IF I can trust the tracker to track through the shot. If I have to babysit it, I would say manual tracking in vegas is faster.

      • BTW, thanks for all your replies here on Blendernation.  So informative.  And when you are obviously busy.  You are an awesome human being.

  4. Regarding the tracking at the first part of the video: You almost never want to have big search areas, unless the tracked scene point is moving fast. What you want is the smallest possible search area that still has the tracked point in the next frame (and maybe 15 pixels of buffer around that). When there is a big search area, the probability of mismatching is increased. Furthermore, with the "Hybrid" tracker used here, an exhaustive search is done which is slow for large search areas.

    • Thanks Keir, I'll keep that in mind. It seemed like it was straying more with a small search area, but in this case the search target is pretty low-contrast, so I'll call that the culprit. ; )

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