2
$\begingroup$

I have a slow motion video of an object falling under gravity with an aproprete scale in the background. It was filmed from a tripod so there is no camera movement in any plane.

What I would like to do idealy is use blender's object tracker to produce graphs of the objects position over time. As I have a lot of clips to process and I don't care about the objects rotation I though of using just a single marker. I have already tracked it.

My question now is how do I get the tracking data to a format that can be imported into exel such as plain text numbers? I see a number of solving options such a planear track but they require more markers. Is there such an option like 2D solve?

$\endgroup$
  • $\begingroup$ How the data should look like (I think there are too many possibilities)? Do you only need the position of the trackers? Or do you only need a way to access the data? BTW: What you want to do with it afterwards? $\endgroup$ – p2or Jan 15 '15 at 17:32
  • $\begingroup$ I just need the position however @wardrums method seams to add an extra degree of accuracy with the plane track. I want to use this to plot positions for falling objects over time $\endgroup$ – Michal Jan 15 '15 at 19:50
3
$\begingroup$

You can use a Follow Track constraint to 'project' a single track onto an object.

  1. track your point, you dont need to solve the camera.
  2. make a plane, and position it perpendicular to the camera... how you want to set this up is up to you, but it will effect the numbers you get out at the end.
  3. add the constraint to an object, i just used the default Cube, and refer to the image bellow on how i set it up.
  4. in the viewport image, I have calculated the motion paths, and you can see the path of the track is on the plane.
  5. click the Constraint to Fcurve button, and it will bake the constraint to XYZ values. Edit: Some times this button doesn't work. An alternative is: Search->Bake Action
  6. you can then write some python to convert your animation to CSV format.

track constraint

3d view

$\endgroup$
  • $\begingroup$ This would be ideal! I have it setup like you do and the track is working, however the Constraint to F-Curve buttons isn't working :( (2.72) Ill try updating to 2.73 $\endgroup$ – Michal Jan 15 '15 at 19:48
  • $\begingroup$ Ok, Search->Bake Action did it for me $\endgroup$ – Michal Jan 15 '15 at 19:52
  • $\begingroup$ the pasteall link you included isn't working anymore. could you post your script as part of your answer? $\endgroup$ – Blixxy Aug 16 '16 at 8:47
  • $\begingroup$ @wardrums please re-upload the file, files in pasteall expire after a few months. Please use blend-exchange.giantcowfilms.com $\endgroup$ – cegaton Nov 10 '16 at 2:14
  • $\begingroup$ @cegaton have done $\endgroup$ – wardrums Nov 14 '16 at 10:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.