Homography from scratch python

1. What is homography in Python?
2. How to do homography in OpenCV?
3. How many points does it take to compute a homography?
4. How do you apply a homography matrix to a point?

What is homography in Python?

What is Homography? Homography is a transformation that maps the points in one point to the corresponding point in another image. The homography is a 3×3 matrix : If 2 points are not in the same plane then we have to use 2 homographs. Similarly, for n planes, we have to use n homographs.

How to do homography in OpenCV?

To calculate a homography between two images, you need to know at least 4 point correspondences between the two images. If you have more than 4 corresponding points, it is even better. OpenCV will robustly estimate a homography that best fits all corresponding points.

How many points does it take to compute a homography?

We have seen that a homography can be used to map one image to the other in the case of pure camera rotation or a planar scene. If such a homography exists between the images, four points are sufficient to specify it precisely.

How do you apply a homography matrix to a point?

This spatial relationship is represented by a transformation known as a homography, H, where H is a 3 x 3 matrix. To apply homography H to a point p, simply compute p' = Hp, where p and p' are (3-dimensional) homogeneous coordinates. p' is then the transformed point.