Simultaneously Track Multiple Moving Objects

[Guest]

I am an animal behaviorist and AfterEffects (CC) may be the key to solving my unique problem. Let's say I have a video of six small animals housed individually in circular arenas.

Can AfterEffects:

• Track each animal simultaneously in real time or track them when the footage is sped up. The latter bit is important since I have hours of footage to track and it would be nice if I could expedite this process.
• Export or copy/paste the 2D positional data (x,y) to a spreadsheet

I know that AfterEffects is capable of tracking a fixed point when the camera is moving. However, I am interested to know if the app can perform the inverse of that scenario: static camera position with multiple moving objects.

Thank you!

[Roei Tzoref · Accepted solution]

Track each animal simultaneously in real time or track them when the footage is sped up. The latter bit is important since I have hours of footage to track and it would be nice if I could expedite this process.

simultaneously:

• you can't track multiple features simultaneously in After Effects using the point tracker. here's what point tracking is. you can always track them one by one in Ae... maybe that's not a big issue after all?
• you can track multiple masks simultaneously Using the After Effects Mask Tracker. but getting the spatial coordinates will be difficult.
• Mocha Ae can do multiple planar tracking. you can then export the layers tracking data one by one to a null and can use the coordinates.
• Syntheyes also can do simultaneously 2d feature tracking and you can export these as nulls to Ae if that's a workaround for you. here how's 2d tracking syntheyes->Ae works

sped up:

you can time stretch the layer (make it faster) then precompose, and then track that result. this means you will track less frames, and as long as the movement is distinctive, it can work.

Export or copy/paste the 2D positional data (x,y) to a spreadsheet

you can apply the tracking data to a property, and then copy that keyframe transform information and paste it as text to any text document if that's what you are asking. you will get something like this:

[Rick Gerard]

Let's break down your requests:

Can AfterEffects:

• Track each animal simultaneously in real time or track them when the footage is sped up. The latter bit is important since I have hours of footage to track and it would be nice if I could expedite this process.

Real time - No, After Effects is a compositing and motion graphics application designed to create shots and moving graphics that you cannot create in a video editing app. As Roei said, you have to set up each track individually, watch the track to make sure that the tracker sticks to the detail you picked out. It will fail and require manual key framing if one animal walks in front of the one being tracked or the animal being tracked walks behind something. If you have an hour of footage and six animals and they each stay visible in the frame and you have a fairly robust machine I would guess that it would take about 2 hours per animal and you'll probably have to break the footage up into smaller chunks because AE is not designed to handle footage longer than a few seconds. So that is about 12 hours per hour of footage.

• Export or copy/paste the 2D positional data (x,y) to a spreadsheet

Roei answered that question. Keyframe data is just delimited text files.

I think you are looking for a motion analysis application. I do not have any suggestions. If you wanted to do some compositing and create a short visual effects shot tracking will do the job for you very nicely. If you want to analyze data you are looking in the wrong tool box.

Edit: I got curious. Maybe something like this: PhysMo - Video Motion Analysis