Projection Mapping With Floor - Post animated camera move

In an example by the VFX breakdown of "Anonymous" they show a show of horses riding into a castle, where the plate looks locked off, and they projection map the floor and the buildings around it. Then, I'm assuming they animate a camera in 3D space to create a small jib shot.

When projecting images with ground plans than need to line up with another ground plane created in 3D space, how do you project without having the floor slip? I've tried this technique and the ground seams to sheer, even with very small movement. I'm thinking the live action footage projection might need to be projected to a card that always faces the camera? Any insights would be great.

Here's the example of that shot from "Anonymous" The Shot starts at 1:24

Do you have the identical situation like in Anonymous breakdown or something else?

Cause if you do its pretty much straightforward stuff where you merge everything with one camera (your live footage with still imagery and displacement either by 3D pass or by hand drawn mask) and then you introduce another camera to get that parallax movement. I'm pretty much sure you are aware of that so I would like to see the instance of your floor slipping/deformation. Maybe you are pushing it too much? In Anonymous its a very subtle movement, you don't even know its there unless you really pay attention.

Thanks, I'm pretty sure I understand the principles here, but i'm not getting the right result. I'll try to make a simple test to post here. The stuff i'm working on is under NDA.

from the video i would guess that they also projected the original footage to a plane and the camera move is so subtle that you dont see the warping/deformation

Thanks, I'm pretty sure I understand the principles here, but i'm not getting the right result. I'll try to make a simple test to post here. The stuff i'm working on is under NDA.

After repeated reading of your original post I think I came to conclusion that you are trying to merge two planes together with two separate projections in 3D space. Am I right?

If you want to post the example just remove NDA imagery and replace it with contrasting gradients so we can see the movement.

from the video i would guess that they also projected the original footage to a plane and the camera move is so subtle that you dont see the warping/deformation

Thanks Michael, that's what I'm guessing too. Some trial an error kind of came up with minimal warping/deformation with this approach.

After repeated reading of your original post I think I came to conclusion that you are trying to merge two planes together with two separate projections in 3D space. Am I right?

If you want to post the example just remove NDA imagery and replace it with contrasting gradients so we can see the movement.

Wouldn't have gotten this far without the suggestion for using gradients. I re-set up the projections with gradients and found them not to slip, so I reversed engineered it, and projected the original footage on a plane, and line that up with ground plane projection. So yes, you're correct in that I'm trying to merge two planes from two separate projections in 3D space.

So, with this approach, I see the need to restrict projections with priority which isn't an issue, but to get everything to line up I need certain sections of different projections on the same geo ( i'm not using planes) Is there a way to automate masks for this type of combined projections? not sure how volume mask could be combined with projections. My other though is to maybe generate vertex maps from 3D?
Thanks again guys.