OpenCV 将仿射变换应用于单个点而不是整个图像 [英] OpenCV Applying Affine transform to single points rather than entire image

问题描述

我在 OpenCV 中从 KeypointBasedMotionEstimator 类获得了一个仿射变换矩阵.

I've got a Affine transform matrix in OpenCV from the KeypointBasedMotionEstimator class.

它的形式如下:

[1.0008478, -0.0017408683, -10.667297;
0.0011812132, 1.0009096, -3.3626099;
0, 0, 1]

我现在想将变换应用于向量

Pointf >，这样它就会变换每个点，就像它们在图像中一样.

I would now like to apply the transform to a vector< Pointf >, so that it will transform each point as it would be if they were in the image.

OpenCV 似乎不允许只转换点，函数:

The OpenCV does not seem to allow transforming points only, the function:

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

似乎只将图像作为输入和输出.

Only seems to take images as inputs and outputs.

有没有办法对 OpenCV 中的单点应用仿射变换?

Is there a way I can apply an affine transform to single points in OpenCV?

推荐答案

你可以使用

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

例如

cv::Mat yourAffineMatrix(3,3,CV_64FC1);
[...] // fill your transformation matrix

std::vector<cv::Point2f> yourPoints;
yourPoints.push_back(cv::Point2f(4,4));
yourPoints.push_back(cv::Point2f(0,0));

std::vector<cv::Point2f> transformedPoints;

cv::perspectiveTransform(yourPoints, transformedPoints, yourAffineMatrix);

不确定 Point 数据类型，但转换必须具有 double 类型，例如CV_64FC1

not sure about Point datatype, but the transformation must have double type, e.g. CV_64FC1

参见 http://docs.opencv.org/modules/core/doc/operations_on_arrays.html#perspectivetransform 也是

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