Introduction
Sometimes it is very convenient to stabilize camera movements temporally, to be able to work with other effect in a static shot situation. And finally reapply the original camera movement. For example this is useful when creating shapes or painting wth the VectorPaint, which is significantly more difficult if the camera is moving.
Before going into the full example, it is recommended to learn basic camera stabilization functions (with no other effects involved), which is covered in this video tutorial:
https://www.youtube.com/watch?v=SCVtwTXi2Zs&list=PLPxezwaoLh179l9nGWhDuvgRLHz_OwtvJ&index=17
For more control, camera stabilization does not need to be all or nothing. You can use it to reduce camera shaking without completely eliminating it, as follows:
You can apply your stabilization curve to the Axis_1 Position X and Y of the Comp3D effect (which will apply for all the layers in your comp), then copy and paste this curves into the Layer_1 Position X and Y, respectively. Then in the curves menu select such parameters and flip them.
As a result you will obtain that each curve cancels the other one, but then with the Scale options you can fine-tune only one of the curves so you can adjust the quantity of Stab/Destab desired. Be aware that, in order to perform Scale operations in any curve, you have to select directly the points in the canvas (just selecting the parameter box is not enough):
I would also recommend you to operate this way because, in case you want to discard the modifications made in any curve, you just delete it and copy-paste and invert again from the original one. In that way once you've tracked anything you don't have to repeat it, as it 'saved' in the parameters' boxes. I also recommend to set the Background options of the Comp3D to 100% Red (or Green or Blue) when dealing with Stab/Destabs, so you will always be visually aware if you are losing image inside your canvas.
Using Comp3D to stabilize the shot while working in other effect:
Now going into the matter, let's suppose that you only want to stabilize the shot for a while in order to work with the VectorPaint effect:
Build a Comp3D with two layers, let Layer01 be the original footage, and the Layer02 the same footage+ another Comp3D + VectorPaint.
In the Comp3D of the Layer02 track and stabilize as usual (via Axis' Comp or at Layer1, it shouldn't matter), then with the Vector Paint perform the required cleanup/clone brush needed.
Compose the Layer02 by drawing a shape in the VectorPaint node (not in the paint menu of the node itself, but in the stack directly)
Finally, copy the stabilization curves in the first Comp3D and paste them in the Layer2 X/Y Position of the overall Comp3D, and flip them in the Curve Editor. This will re-apply the original movement of the footage only to the painted patch masked, and will compose with the original footage.
Note that we have used nested Comp3D effects, that is, one Comp3D is "inside a layer" of the other, not one Comp3D "applied" to the other. This is because in that way the second Comp3D would receive the image already cropped, and it would not receive have the cropped pixels to bring them back.
