Reprojecting an image to another viewpoint using planar homography

1. What is planar homography?
2. What is homography in image processing?
3. What is preserved in a homography what is not preserved in a homography?
4. What is homography used for?

What is planar homography?

We can derive a linear relationship between the coordinates of points on an arbitrary plane in the scene and the coordinate of that point in the image. This is the planar homography and it has a number of everyday uses which might surprise you.

What is homography in image processing?

Homography, also referred to as planar homography, is a transformation that is occurring between two planes. In other words, it is a mapping between two planar projections of an image. It is represented by a 3x3 transformation matrix in a homogenous coordinates space.

What is preserved in a homography what is not preserved in a homography?

Projective transformation (homographies)

A homography, also called projective transformation, preserves lines but not necessarily parallelism.

What is homography used for?

Homography is generally used to map a plane to another plane while fundamental matrix is used to calculate depths of scene structure with objects of varying depths.