nms算法c++实现_nmsboxes源码 c++

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

typedef struct Bbox
{
    int x;
    int y;
    int w;
    int h;
    float score;

}Bbox;

bool sort_score(Bbox box1,Bbox box2)
{
    return (box1.score > box2.score);

}

float iou(Bbox box1,Bbox box2)
{
    int x1 = std::max(box1.x,box2.x);
    int y1 = std::max(box1.y,box2.y);
    int x2 = std::min((box1.x + box1.w),(box2.x + box2.w));
    int y2 = std::min((box1.y + box1.h),(box2.y + box2.h));
    float over_area = (x2 - x1) * (y2 - y1);
    float iou = over_area/(box1.w * box1.h + box2.w * box2.h-over_area);
    return iou;
}
//方法1
vector<Bbox> nms(std::vector<Bbox>&vec_boxs,float threshold)
{
    std::sort(vec_boxs.begin(),vec_boxs.end(),sort_score);
    std::vector<Bbox>del(vec_boxs.size(),false);
    for(int i =0; i<vec_boxs.size();i++)
    {
        for (int j =0;j<vec_boxs.size();j++)
        {
            float iou_value =iou(vec_boxs[i],vec_boxs[j]);
            if(iou_value>threshold)
            {
                del[j]=true;
            }
        }
    }
     std::vector<Bbox>results;
    for(const auto i :del)
    {
        if(!del[i]) results.push_back(vec_box[i]);
    }
    return results;
}
//方法2  这种执行效率更高
vector<Bbox> nms(std::vector<Bbox>&vec_boxs,float threshold)
{
    vector<Bbox>results;
    while(vec_boxs.size() > 0)
    {
        std::sort(vec_boxs.begin(),vec_boxs.end(),sort_score);
        results.push_back(vec_boxs[0]);
        for(int i =0;i <vec_boxs.size()-1;i++)
        {
            float iou_value =iou(vec_boxs[0],vec_boxs[i+1]);
            if (iou_value >threshold)
            {
                vec_boxs.erase(vec_boxs[i+1]);
            }
        }
        vec_boxs.erase(vec_boxs[0]);

    }
}
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