How to place text on sheet of paper in video when camera move keeps hiding parts of it

[A.I.1]

I have a short video (under 5 seconds) with a piece of paper (I'm guessing A4 size) on a desk (the paper is stationary throughout, but the camera moves) that I need to place text on (though I'm supposed to place text on it, I think I may also be able to just replace the paper with an entirely digital version).

The paper has 9 drawn tracking markers on it (but they don't look very good - though they look like they're supposed to be evenly spaced, they don't really look like they are - they don't look measured/drawn accurately),

The problem is the camera moves (eg. up, and at one point only 1 tracking marker on the paper and 2 corners of the (A4?) paper are visible). Also something in the foreground keeps covering some of the tracking markers. I tried using the corner pin effect and manually keyframing it to place a digital paper onto the video, guessing at where the 4 corners of the paper were when some of the corners weren't in the frame (I also tried just placing the text, without the paper). The problem is, because the 2 lower corners of the paper are often not in the frame, the guessing at where they would be in the frames means it isn't placed accurately and so the placement moves around unrealistically.

Is there any good way of achieving this (maybe using 3D tracking and placement?)?

[Mylenium]

Yes, you use 3D tracking to reconstruct the motion. Other than that you could attempt mocha's planar tracker, which also is able to figure in obscurations by ways of mocha's layered shape system. Once you have a valid solve, it should be easy enough to create whatever you need in a pre-comp and apply it to the track.

Mylenium

[A.I.1]

Thanks. I'm trying it with Mocha now. I've never really used that before. I did have a go at tracking the camera in 3D with After Effects but couldn't figure out how to get it to position my composition of a piece of paper/text over the paper in the video (basically I couldn't do it with using AE & 3D camera when I tried - I might watch some tutorials on that). Thanks a lot.

[A.I.1]

Update: I've had a go at using Mocha to track the (A4?) paper but that goes all wrong when the bottom of the paper goes out of the frame. I'll try to find a tutorial on it/read more about it etc.

[Warren Heaton]

As the bottom of the paper moves out of frame, you many need to finish by tracking something that remains in the frame, calculating the offest, and then combining the result with your earlier track.

[Rick Gerard]

As Mylenium suggested, track in Mocha. Have the spline include a bit of the desktop and make sure perspective is enabled. Then copy the corner pin data and paste it to your replacement paper layer in After Effects. This is really basic planar tracking and Mocha is very good at it. There are a bunch of tutorials on the Borris FX website. Type track in Mocha in the search help field at the top right corner of AE to find resources on tracking. This is a really in depth explanation of tracking. Boris FX | Webinar: Tracking Screens with mocha