Is it possible to obtain front-parallel view of image or camera position by 2d-3d points relation using OpenCV?
For this I have intrinsic and extrinsic parameters. I have also 3d coordinates of set of control points (which lies in one plane) on image (relation 2d-3d).
In fact I need location and orientation of camera, but it is not difficult to find it if I can convert image to fronto-parallel view.
If it is not possible to do with OpenCV, are the other libraries which can solve this task?
Solution is based on the formulas in the OpenCV documentation Camera Calibration and 3D Reconstruction
Let's consider numerical form without distortion coefficient (in contrast with matrix form).
We have u and v.
It is easy to calculate x' and y'.
But x and y can not be calculate because we can choose any non-zero z.
Line in 3d corresponds to one point in 2d image.
To solve this we take two points for z=1 and z=2.
Then we find 2 points in 3d space which specify line (x1,y1,z1) and (x2,y2,z2).
Then we can apply R-1 to (x1,y1,z1) and (x2,y2,z2) which results in line determined by two points (X1, Y1, Z1) and (X1, Y1, Z1).
Since our control points lie in one plane (let plane is Z=0 for simplicity) we can find corresponding X and Y point which is a point in 3d.
After applying normalization from mm to pixels we obtain fronto-parallel image.
(If we have input image distorted we should undistort it first)