单应性和仿射变换 [英] Homography and Affine Transformation

问题描述

您好，我是计算机视觉的初学者，如果您要查找两幅图像之间的转换以及为什么要使用它，我想知道单应性和仿射变换之间的确切区别是什么.从我在线上找到的论文和定义中，我还没有找到它们之间的区别，以及它们之间的区别.

感谢您的帮助.

解决方案

我已按照外行的条款将其设置为空.

Homography

单应性是将一个图像中的给定点集映射到另一图像中的对应点集的矩阵.

单应性是一个3x3矩阵，它将第一个图像的每个点映射到第二个图像的对应点.参见以下内容，其中H是针对点x1, y1和x2, y2

计算的单应性矩阵

考虑以下图像的要点:

在上述情况下，生成了4个单应性矩阵.

在哪里使用?

1. 您可能需要对齐上面描述的图像.您可以通过使用单应性来做到这一点.

此处第二张图片相对于第一张图片

2. 另一个应用程序是全景拼接

访问此博客以获取更多信息

仿射变换

仿射变换生成矩阵以相对于整个图像变换图像.它不像单应性那样考虑某些点.

因此，在仿射变换中，线的平行性始终保持不变(如EdChum所述).

在哪里使用?

它用于要更改整个图像的区域:

• 旋转(自我理解)
• 平移(将整个图像上下左右或左右移动一定长度)
• 缩放(基本上是缩小或放大图像)

有关更多信息，请参见此页面

Hi i am a beginner in computer vision and i wish to know what exactly is the difference between a homography and affine tranformation, if you want to find the translation between two images which one would you use and why?. From papers and definitions I found online, I am yet to find the difference between them and where one is used instead of the other.

Thanks for your help.

解决方案

I have set it down in the terms of a layman.

Homography

A homography, is a matrix that maps a given set of points in one image to the corresponding set of points in another image.

The homography is a 3x3 matrix that maps each point of the first image to the corresponding point of the second image. See below where H is the homography matrix being computed for point x1, y1 and x2, y2

Consider the points of the images present below:

In the case above, there are 4 homography matrices generated.

Where is it used?

1. You may want to align the above depicted images. You can do so by using the homography.

Here the second image is mapped with respect to the first

2. Another application is Panoramic Stitching

Visit THIS BLOG for more

Affine transformation

An affine transform generates a matrix to transform the image with respect to the entire image. It does not consider certain points as in the case of homography.

Hence in affine transformation the parallelism of lines is always preserved (as mentioned by EdChum ).

Where is it used?

It is used in areas where you want to alter the entire image:

• Rotation (self understood)
• Translation (shifting the entire image by a certain length either to top/bottom or left/right)
• Scaling (it is basically shrinking or blowing up an image)

See THIS PAGE for more

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