Join Chris Meyer for an in-depth discussion in this video 3D camera tracking, part of After Effects Apprentice 19: Motion Tracking with CINEMA 4D Lite.
- View Offline
- [Voiceover] Let's preview our footage and discuss what the client wants us to do. Here we have the camera through a forest originally looking at the tops of the trees and panning down to look at this path going through the forest. Our client wants to create a fairy tale where a king's crown is discovered lost on this trail. However, as you can see, there is no crown in the original footage. So what we need to do is create a crown in Cinema 4D and have it match the camera move in our original footage. Then we need to composite those two worlds together in a convincing fashion.
No problem. We actually have all the tools you need to this in After Effects with Cinema 4D Lite. The first thing we need to do is recreate this original camera shot. To do that, we'll select the footage and either use animation, track camera or make sure that the tracker window is open, which it is over here, and click track camera. After Effects will automatically look through this clip trying to identify as many nice trackable points as it can in the footage.
And then once it's tracked those points, it will use that data to reverse engineer the original camera move. It will keep you up-to-date on its progress here in the effects control panel. It's done finding points. Now, it's trying to reverse engineer that camera. This does take a few seconds, so I'll cut ahead to where it's done. When After Effects is done, you should see a number of colorful crosses overlaid on your footage. If you accidentally deselect the 3D camera tracker, you will no longer see those points. But when you select it, you'll see them again.
These are the points that After Effects has tracked in the footage. Ideally, they should only track objects that are not moving in the original shot. If they're tracking something that is moving, it's gonna give it a false reading. And sometimes you'll see track point just kind of wander through a shot, when it should be attached to something stationary. I'm going to increase my track point size, so I can see my points a little bit more clearly. And drag my current time indicator through this clip. And make sure that I don't have any bogus points in this shot. After Effects tracking something that is not really stable, or that there's any wandering points.
If I did find a point that I thought was not accurate, for the sake of argument, we'll take this one on the leaves in front of us. I'd select it and press the delete key. This would cause After Effects to resolve the camera with this new set of data, and when it's done, it should have a more accurate solution for the camera. Now this is the point where we need to discuss what I consider to be a bug in After Effects. In both CC 2014 and CC 2015, you'll actually get different results depending on what CPU your computer is running.
I'm running an old 12 core Mac Pro here and I'm getting good points, including ones on this path which will be very critical because I want to place my crown on this path. However, when I run this exact same footage on my brand new iMac, I don't get any points on the path, only up in the trees. If you're trying to execute this course in a version of software that has this bug, and you don't get any track points here along the path, go back to the project panel and instead, use our camera tracking, tracked composition.
You select the 3D camera tracker, you'll see there are points already along this path. That's what you should use if you cannot get an acceptable track with the shot we gave you. But if you do have points on your path, move ahead with this composition.
The first course in the series, After Effects Apprentice 17, includes an overview of the C4D Lite user interface, as well as important setup information you need to know whenever you use live C4D layers in After Effects. We recommend you watch it first if you have no prior experience with C4D.
- 3D camera tracking
- Setting a ground plane and origin
- Merging an After Effects camera move into a C4D project
- Adding a 3D model to the scene
- Casting and compositing shadows
- Improving the final composite