Hi Etamar,
It is my understanding that, you want to know the difference between ‘fitgeotform2d’ and ‘estgeotform2d’ functions and which algorithms are used for them, also how to transform individual points and not the whole image.
The function 'estgeotform2d' estimates 2-D geometric transformation from matching point pairs, whereas 'fitgeotform2d' fits a transformation to the control point pairs. There is also a difference in the types of geometric transformation objects returned in both cases. You can refer to following documentation pages for more information on this:
The algorithm used for function 'estgeotform' is M-estimator sample consensus (MSAC) to exclude outliers(refer https://www.mathworks.com/help/vision/ref/estgeotform2d.html?s_tid=answers_rc2-2_p5_MLT#mw_884abd94-6959-485b-8a56-8d027548518e). And to know about the algorithm for 'fitgeotform' refer https://www.mathworks.com/help/images/ref/fitgeotform2d.html?s_tid=doc_ta#mw_bbf65ade-c8b1-456a-b5bc-dd822a6ceb83
And, to transform individual points instead of whole image in each case, use 'transformPointsForward' function that you can use on those points. Also, you must use 'worldToIntrinsic' function to convert the output of above function in world coordinates to intrinsic coordinates, as follows:
[B,RB]= imwarp(A,tform);
[x,y]= transformPointsForward(tform, u, v);
[xIntrinsic, yIntrinsic]= worldToIntrinsic(RB,x,y);
where 'tform' is the output from 'estgeotform' or 'fitgeotform' and RB is a spacial referencing object.
Please refer the below documentations links for more information on above functions:
Hope this helps!
Regards,
Rasmita
