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Using 'Zero Weighted Tracks' in Blender

Sebastian König makes clever use of trackers with a weight of 0 to recreate part of the geometry of a scene, to assist in remodelling it for your tracked footage. The result is fairly impressive for such a simple procedure.

Sebastian writes:

One of the new things in Blender 2.70 is the Weight setting for tracks in Blender. With zero weighted tracks you can easily measure your scene with lots of markers without affecting your carefully tracked and calculated 3D camera solution.


  • PhysicsGuy

    Yeez, why didn't I think of that! I had the problem once that I needed additional trackers to find out where to place an object in 3d space, but I couldn't get a good enough track on those points. I tried doing it by doing an object track, but than you need to know the scale of the object. Even though I read about track weights, the coin didn't drop! So thanks Sebastian!

    • onjoFilms

      Don't kick yourself too hard. This is a new feature.

      • PhysicsGuy

        It is just that I pride myself at being up to date *grin*

        • onjoFilms

          Well, you know what they say, 'pride' is just a bunch of lions.

  • Peter Boos

    now you have a point cloud, i guess this will turn into single camera 3D reconstruction tool for blender ?
    If it could determine plane, textures, and build a surface from it, then your verry close to that

    • PhysicsGuy

      The big question is whether it is really faster to use a pointcloud tool, then to actually build the geometry yourself. For this you don't really need a point cloud, just a few strategically placed markers. Ofcourse, a point cloud has the benefit that you can actually perform a least-squares fit using a lot of point that you know should be on you surface. That way, the impact of a few problematic markers is reduced.

      • Peter Boos

        Welll it would realy cool if with doodling around an object with your camera, it could be converted to a 3d shape. Sure we can create stuf, but sometimes you want to fit things in combination with 3d printing, then you need a real point cloud, if that could be made out of blender video conevrsion it would be super i think

  • FluxCapacitance

    Blender is becoming a fancy 3D scanner for any reasonable camera. :)

  • Tim Bahrij

    He's a smart man, that Sebastian König!

  • Rocket

    Well, that's helpful. Thanks for the trick.

    Does anybody know if you can exchange information between the 3d camera tracker on after effects to blender?
    Because we are in seriously in need of a efficient 3d tracker. I'm wondering If with the release of the new blender movie, the video function will benefit of some upgrades.

    • stephen

      There's already an add-on for sending a blender scene to AE. So, it's just a case of doing the track, turning the track markers into empties, then running the Blender to AE script. Inside of AE, you'll then have all the empties as null objects (I think... It's been a while...)

      • Guest

        That is a perfect case for a macro-style addon. All the pieces are there, if it could just be scripted to remove the need to manually do the inbetween steps. It could be called "convert track to AE export" or something.

        • stephen

          That's an idea, but I'm not sure what steps could be macro-ized. After tracking, setting up the scene (adding the null objects to the scene and linking the tracked camera motion to the Blender camera) is already just one button click, very simple. Once you have that, it's just a case of selecting everything you want in After Effects and running the AE script to export to After Effects. Here's the add-on page:
          Not sure if it would be worth having a 'convert track to AE export' button in the tracker, that's quite a specific function that won't be used too much I'm thinking. Plus, if other applications get a similar export script in Blender, would you simply have a list of buttons for each application? Export to... Motion, Nuke, Smoke...
          It's also worth considering that these applications also have trackers. Not sure if they're as good as the Blender tracker, but it makes the use even more niche as most people will just use the built-in tracker...

          • Rocket

            That seems to be a logical prediction, Is it? I wish to point out the need of communicating with one of the most used compositing software which is after effects. Countless filmmakers (including me), can't imagine our life without it.

            Still, my original idea was to create the tracking on AE and then export it to blender. That will save you a ridiculous amount of time. Here is a link how simply the communication between Cinema 4d and after effects is.

          • stephen

            What seems to be a logical prediction? I'm all for exchanging data between applications, but I was simply saying to the guest poster above that having a macro button to export the tracking data from Blender to After Effects might be a bit overkill, seeing as the process is so simple already, especially considering that the interface is already pretty cluttered.

            Calm down, believe it or not, I use other applications too. I used Internet Explorer this morning to check my Facebook and then I had a riveting game of minesweeper. I'm now back in Blender to write a letter to my mum. Really wish someone would write a script so I can print from Blender... My workflow of taking a screenshot and printing from MS Paint isn't really ideal...

            Yes, exchange between AE and C4D is very easy, has been like this for a while, been one of the bigger strengths of C4D, which has recently gotten a whole lot better since the inclusion of C4D Lite with CC. I'm sure if Blender struck such a deal with Adobe, exchange of data between the two applications would be much smoother too.

            To be honest though, I don't think it's something that would be in huge demand.... Blender has a great tracker, do the tracking there, then transfer to After Effects, rather than the other way around, just needs a bit of forethought to plan the workflow... If not, maybe hire a developer to write a python script that will import the AE tracking data. Or learn to write the script yourself...

          • stephen

            Also, why are we in serious need of an 'efficient' 3D tracker? What's inefficient with Blender's current tracker?

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