OpenCV Q&A Forum - RSS feedhttp://answers.opencv.org/questions/OpenCV answersenCopyright <a href="http://www.opencv.org">OpenCV foundation</a>, 2012-2018.Wed, 26 Feb 2014 01:47:22 -0600Finding 3D coordinate when all 3 coordinates can vary in the object coordinate systemhttp://answers.opencv.org/question/29067/finding-3d-coordinate-when-all-3-coordinates-can-vary-in-the-object-coordinate-system/I have the 3D coordinates of 4 coplanar points of my target in the object coordinate system.I also have their the 2D coordinates in every frame of a video.I have also calculated the intrinsic parameters (M) for the camera, the R (rotation) and t (translation) matrices between the object coordinate system and the camera coordinate system using solvepnp(). I have read [from here](http://stackoverflow.com/questions/12299870/computing-x-y-coordinate-3d-from-image-point) the complete process,which is very clear.It is also similar to the process I followed.Therefore I wanted to use the same equation
s [u v 1]<sup>T</sup> = M ( R [X Y Z]<sup>T</sup> + t)
for calculating my 3D coordinates but I have no constant as the link explains for calculating s.My target rotates about the x axis in the OpenCV coordinate system.My questions are -
1. Can anyone suggest me a way to find
s? Is it definitely mandatory for
this calculation or can i use s=1?
2.
Is there any other methods for
calculating the 3d point with what
parameters I have?silentvalleyWed, 26 Feb 2014 01:47:22 -0600http://answers.opencv.org/question/29067/