# 计算机视觉常用工具

## Eigen

* [将Eigen中的vector4f变成vector3f](https://stackoverflow.com/questions/25104665/best-way-to-convert-an-eigen-vector4-type-to-vector3)

## OpenCV

* [OpenCV逐元素访问时使用的类型](https://stackoverflow.com/questions/30596158/how-to-find-out-what-type-to-use-for-opencv-at-function-in-c)

```
        C1      C2     C3     C4     C6
CV_8U   uchar   Vec2b  Vec3b  Vec4b
CV_8S   char    -       
CV_16U  ushort  -
CV_16S  short   Vec2s  Vec3s  Vec4s
CV_32S  int     Vec2i  Vec3i  Vec4i
CV_32F  float   Vec2f  Vec3f  Vec4f  Vec6f
CV_64F  double  Vec2d  Vec3d  Vec4d  Vec6d
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://blog.cweihang.io/cv/utils.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.