AE Mocha Tracking Planar Surface

[Blaise Douros]

Hey Roei,
Great questions. Answers follow:

1. No, I didn’t prep the footage; the one thing that I did differently was track from the beginning of the clip until the camera pans over to the hallway, to give the 3D tracker more movement data to work with. When it solved the camera, it gave me “Error, could not solve camera for these frames” towards the end, but that didn’t matter to me–all I wanted was the window data, so I trimmed the clip on which the tracker was applied so those error frames wouldn’t appear. I ended up putting a duplicate clip (with no tracker applied) above the exterior plate to use for the rotoscoping, but left the tracked copy in for reference.

2. I’ve found that the 3D Camera Tracker is somewhat good at guessing AOV, but whenever I have any information on the angle of view, I specify it. I’ve done a lot of testing, and it seems to make the tracker more accurate–and that makes sense, given that After Effects can now estimate the expected depth and movement of the scene based on the lens width. At the very least, it results in a virtual camera whose focal length (and thus, characteristics when interacting with the virtual objects in the scene) match the taking lens. As for how I guessed the angle…it was just a guess based on what I could see in the scene. I shoot as well as edit and work in After Effects, so my eye is somewhat accustomed to estimating that kind of thing.

3. Yes, that’s true, but it’s nice to be able to do it so quickly based on the tracking information in the scene, and as you say, without leaving AE. But I take your point. Mocha is probably a better and more accurate choice for tracking the window frame and building the foreground matte. I like the 3D camera tracker for a lot of other applications (I do a lot of titles that are tagged into the scene’s 3D space), so I’ve gotten pretty comfortable with it–it’s an easy solution for a lot of problems. I need to get more fluent in Mocha, though. Great conversation!

[Roei Tzoref]

[Blaise Douros] “1. No, I didn’t prep the footage; the one thing that I did differently was track from the beginning of the clip until the camera pans over to the hallway, to give the 3D tracker more movement data to work with. “

yes. there is no point tracking when the window leaves the frames. strangely in my setup I can’t seem to solve it from the beginning of the shot but only right before the window appears – which is just as good of course, just makes me wonder why didn’t it work

[Blaise Douros] “I’ve found that the 3D Camera Tracker is somewhat good at guessing AOV”

this is great info. I will try that in the future.

[Blaise Douros] ” I like the 3D camera tracker for a lot of other applications (I do a lot of titles that are tagged into the scene’s 3D space), so I’ve gotten pretty comfortable with it–it’s an easy solution for a lot of problems. I need to get more fluent in Mocha, though. Great conversation!”

I tend to not use 3D camera tracker because my needs are more with compositing in 2d for vfx and not adding titles. I find it’s much easier for me to composite in 2D than in 3D (it is a pain really). I know I should use it more though.. especially when there is perspective information in the scene.. you got my exercise files and I got yours so I will be happy to trade information in the future of you have any trouble with mocha, and I will use your knowledge with my 3d track solving…

here’s a thread with a 3d camera tracking and composting I am actually proud of since I don’t do it much and mocha would have been a little more pain doing it I Imagine ☺ https://forums.creativecow.net/thread/2/1116664

Roei Tzoref
After Effects Artist & Instructor
♫ Ae Blues Tutorials