SIFT+RANSAC算法做图像匹配的学习与实现

为了这玩意blhx-auto-project我需要做一个图像匹配的玩意,一路顺藤摸瓜摸到了RANSAC+SIFT,这里研究一下。

相关资料:

Wikipedia:scale-invariant feature transform (SIFT)
Wikipedia:Random sample consensus (RANSAC)
Github:RobHess的源码(SIFT+RANSAC)(C++)
博客:RobHess的SIFT源码分析:综述
博客:RANSAC算法详解
博客:利用RANSAC算法筛选SIFT特征匹配
scikit-image:Robust matching using RANSAC(Python)
发现我绕远了
opencv上有相关Demo
github上还有图片拼接的相关代码
基本上没我啥事了

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GitHub GraphQL API [Quick Start](新手友好)

由于软工项目选的是社交好友分析,又得捡起爬虫的那一套理论。。。社交好友分析应用数据才是王道,没有数据就没有发言权。写一个稳定的爬虫还是很重要的。准备爬github的时候发现github已经不再使用REST API,而是用的一个叫GraphQL API的东西。github上的教程在,但是把这一套教程从头到尾看完花了我几个小时,于是想在这里写一个快速上手教程。

Hint:github GraphQL API 网页版测试工具 很好用,侧面还有文档,可以随时查,很方便

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在java语言中使用Graphviz画图

 上图是使用Graphviz画图的一个示例,它是由以下dot脚本生成的。

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2017ICPC北京网络赛 G | hihocoder 1584 Bounce

For Argo, it is very interesting watching a circle bouncing in a rectangle.

As shown in the figure below, the rectangle is divided into N×M grids, and the circle fits exactly one grid.

The bouncing rule is simple:

1. The circle always starts from the left upper corner and moves towards lower right.

2. If the circle touches any edge of the rectangle, it will bounce.

3. If the circle reaches any corner of the rectangle after starting, it will stop there.

Argo wants to know how many grids the circle will go through only once until it first reaches another corner. Can you help him?
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2017ICPC北京网络赛 B | hihocoder 1579 Reverse Suffix Array

描述

There is a strong data structure called “Suffix Array” which can effectively solve string problems.

Let S=s1s2…sn be a string and let S[i,j] denote the substring of S ranging from i to j. The suffix array A of S is now defined to be an array of integers providing the starting positions of suffixes of S in lexicographical order. This means, an entry A[i] is the starting position of the i-th smallest suffix in S and thus for all 1 < i ≤ n:  S[A[i-1], n] < S[A[i], n].

For example: the suffix array of “banana” is [6, 4, 2, 1, 5, 3].

Here comes another problem called “Reverse Suffix Array”.

Given a suffix array, you need to figure out how many lower case strings are there whose suffix array is the same as the given suffix array.
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