c++版 nms

定义的box是左上角的x、y以及宽度w、高度h

iou计算出来的交集的w、h必须判断是否大于0，这避免了两个框没有交集的情况。如果不判断，可能存在w、h都为负生成iou>0的情况进而影响结果。

+1操作是计算像素点个数，这个地方其实有点没太理解到，但开源的代码都是这么写的。

#include<iostream>

#include<vector>

#include<algorithm>

#include <stdio.h>

#include <stdlib.h>

using namespace std;

typedef struct Bbox{

    int x;

    int y;

    int w;

    int h;

    float score;

}Bbox;

class Solution {

public:

    static bool sort_score(Bbox box1,Bbox box2){

        return box1.score > box2.score ? true : false;

    }

    float iou(Bbox box1,Bbox box2){

        int x1 = max(box1.x,box2.x);

        int y1 = max(box1.y,box2.y);

        int x2 = min(box1.x+box1.w,box2.x+box2.w);

        int y2 = min(box1.y+box1.h,box2.y+box2.h);

        int w = max(,x2 - x1 + );

        int h = max(,y2 - y1 + );

        float over_area = w*h;

        return over_area/(box1.w * box1.h + box2.w * box2.h - over_area);

    }

    vector<Bbox> nms(std::vector<Bbox>&vec_boxs,float threshold){

        vector<Bbox>results;

        std::sort(vec_boxs.begin(),vec_boxs.end(),sort_score);

        while(vec_boxs.size() > )

        {

            results.push_back(vec_boxs[]);

            int index = ;

            while(index < vec_boxs.size()){

                float iou_value = iou(vec_boxs[],vec_boxs[index]);

                cout << "iou:" << iou_value << endl;

                if(iou_value > threshold)

                    vec_boxs.erase(vec_boxs.begin() + index);

                else

                    index++;

            }

            vec_boxs.erase(vec_boxs.begin());

        }

        return results;

    }

};

int main(){

    Solution a;

    vector<Bbox> input;

    // Bbox box1 = {1,1,1,1,0.3};

    // Bbox box2 = {0,0,2,2,0.4};

    //Bbox box1 = {1,3,2,2,0.3};        //iou为负

    //Bbox box2 = {0,0,2,2,0.4};

    //Bbox box1 = {4,4,2,2,0.3};

    //Bbox box2 = {0,0,2,2,0.4};

    // Bbox box1 = {4,4,1,1,0.3};

    // Bbox box2 = {0,0,2,2,0.4};

    // Bbox box1 = {3,3,1,1,0.3};

    // Bbox box2 = {0,0,2,2,0.4};

    input.push_back(box1);

    input.push_back(box2);

    vector<Bbox> res;

    res = a.nms(input,0.3);

    // for(int i = 0;i < res.size();i++){

    //     printf("%d %d %d %d %f",res[i].x,res[i].y,res[i].w,res[i].h,res[i].score);

    //     cout << endl;

    // }

    return ;

}