warpPerspective 和perspectiveTransform 有什么区别? [英] What is the difference between warpPerspective and perspectiveTransform?

问题描述

我使用了四组点来获得透视变换矩阵.然后使用warpPerspective 将矩阵A 转换为矩阵B.来自 Mat A 的点 a.我想在 mat B 中获得新点的位置.但是 warpPerspective 不能这样做，而 perspectiveTransform 可以.

I have used four sets of points to get a perspective transform matrix. Then using warpPerspective to transform the matrix A to matrix B. Point a from Mat A. I want to get the new point a position in mat B. But warpPerspective cannot do that, while perspectiveTransform can.

这里我想通过warpPerspective来知道perspectiveTransform得到的位置是否与矩阵B中的位置相同.

Here I want to know if the position that perspectiveTransform gets is the same as the position in matrix B by using warpPerspective.

那么，warpPerspective 和 perspectiveTransform 有什么区别?

So, what is the difference between warpPerspective and perspectiveTransform?

Mat trans = getPerspectiveTransform(dst, gpsPoints);
warpPerspective(A, B, trans, image.size());
Point2f a = Point2f(..., ...);         //were known
vector<Point2f> obj(1);
obj[0] = a;
vector<Point2f> b; 
perspectiveTransform(obj, b, trans);//if the new point in B is c, is c equals to b?

推荐答案

warpPerspective 适用于图像.换句话说，warpPerspective 可以使用 H(Homography 或 warpMatrix)扭曲图像 A 并将结果放在 B 中，因此它具有以下结构:

warpPerspective works for images. In other words, warpPerspective can warp image A and put the result in B using the H (Homography or warpMatrix) so it has the following struct:

void warpPerspective(InputArray src, OutputArray dst, InputArray M, Size dsize, int flags=INTER_LINEAR, int borderMode=BORDER_CONSTANT, const Scalar& borderValue=Scalar())

src 是您要变形的 Mat，dst 将存储结果.

src is the Mat you want to warp, dst where the result will be stored.

perspectiveTransform 适用于一组点.它将 H(Homography 或 warpMatrix)应用于一组点(例如在 vector 中)并将结果放入另一个 vector.结果是应用变形后第一个 vector 中的点.它具有以下结构:

perspectiveTransform works for set of points. It applies the H (Homography or warpMatrix) on set of points (which are in vector for example) and put the results in another vector. The results are the points in the first vector after applying the warping. it has the following struct:

void perspectiveTransform(InputArray src, OutputArray dst, InputArray m)

其中 src 是输入点，dst 是输入点变形的结果.

where src is the input points, dst is the results of warping the input points.

结论:

数学上，他们都做同样的事情，即使用 H 扭曲一组点.

Mathematically, they both do the same thing which is warping a set of point using H.

技术上，warpPerspective 在Mat 的坐标上执行此操作并将像素值(颜色)移动到新像素.perspectiveTransform，它只是计算点的新坐标并将其存储在新的vector中.

Technically, warpPerspective do this on the coordinates of the Mat and move the pixel value(color) to a new pixel. perspectiveTransform, it just compute the new coordinate of the point and store it in the new vector.

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