estimateAffinePartial2D without scaling

Describe the feature and motivation

I use estimateAffinePartial2D function to stabilize a set of images of a fixed camera dedicated to coastline monitoring. The camera zoom is fixed. There are small camera movements due to for example the thermal dilation of the structure on which the camera is installed.

The stabilization result with estimateAffinePartial2D is quite good, but it could be really better if scaling factor was not computed and left to 1, as it would better suit the camera configuration.

It would be great to have a boolean parameter in estimateAffinePartial2D, in which the user can specifiy if scaling factor has to be computed or not. Otherwise, it might be more simple to implement an other function called for example 'estimateRigidBody2D' that would compute a rigid body (translation + rotation) transformation from matching points.

Additional context

No response

Start with the estimateAffinePartial2D API and its documentation link. Determine how to expose an option that fixes scaling at 1, or whether a separate rigid-body transform entry point is needed. Done means matching points can produce translation and rotation without estimating scale, with the API behavior documented and tested.