# what is the difference between a projective mapping(transformation) and perspective mapping(transformation)

(1)a projective but not perspective mapping indicates that they are different

(2)Perspective Transform & Homography Matrix indicates these are the same thing

it is evident (1) conflicts with (2) and (3). how can pinpoint these ?

• Don’t try to look for consistency of terminology in different subdomains. For instance, “linear” means rather different things in different contexts. – amd Mar 17 at 20:06

The blog post (2) gets it wrong. The OpenCV's getPerspectiveTransform function seems to be incorrectly named. It should be called getProjectiveTransform, I suppose, but presumably nobody in that community objects.
• It’s common in computer graphics to call a plane homography a “plane projective transform.” To muddy the waters further, the mapping from $\mathbb P^3$ to $\mathbb P^2$ that models a pinhole camera is also called a “projective transformation.” – amd Mar 17 at 20:03