android - Rectify a rectangle to get area

Question

I need to get the area of a known object inside a scene to get the distance from that. The problem is rectifying it so that the area is independent from the angle. I'm using opencv (on Android) with some java code that is equivalent to this:

http://docs.opencv.org/doc/tutorials/features2d/feature_homography/feature_homography.html#feature-homography

In other words: how do i get the area of the object observed perpendicularly from that distance given the H matrix.

Thank you in advance and sorry for my poor english... :)

Answer 1

您可以调用 cvCalibrateCamera，但不确定它是否仅适用于一张图像。它所基于的算法可以处理一个图像的情况，见第 3.1 节。它说“如果n = 1 ...”。因此，您可以在紧要关头重新实现它。