Compare the efficiency of different solvePnP flags

[loqoman]

We have always used CV_ITERATIVE when using solvePnP, there is a potential for efficiency with other methods of solvePnP organization

From an email by Dana:
CV_ITERATIVE Iterative method is based on Levenberg-Marquardt optimization. In this case the function finds such a pose that minimizes reprojection error, that is the sum of squared distances between the observed projections imagePoints and the projected (using projectPoints() ) objectPoints .

CV_P3P Method is based on the paper of X.S. Gao, X.-R. Hou, J. Tang, H.-F. Chang “Complete Solution Classification for the Perspective-Three-Point Problem”. In this case the function requires exactly four object and image points.

CV_EPNP Method has been introduced by F.Moreno-Noguer, V.Lepetit and P.Fua in the paper “EPnP: Efficient Perspective-n-Point Camera Pose Estimation”.

i think it might be interesting (and relatively quick) to compare the results from each method in quality and speed.

[loqoman]

@JeffreyTT Small write up on this?