我正在尝试将对opencv的groupRectangles()的调用从python转换为c ++，并注意到python绑定的输出与c ++调用的输出不匹配。
我已经编辑了以下输出，以反映使用opencv 3.2在ubuntu 18.04上重制此输出
库版本
我正在Ubuntu 18.04上运行opencv。
该c ++程序与opencv 3.2.0链接（如ldd所报道）。
python模块报告版本3.2.0
C ++代码
我编写了以下程序，以获取一组（x1，y1，x2，y2）输入，并将它们传递给groupRectangles()，其组阈值为3，ε为0.02。为了便于比较，输出以python的列表格式打印。
#include <opencv2/opencv.hpp>
#include <iostream>
#include <vector>
// display in python format
std::ostream& operator<<(std::ostream& out, std::vector<cv::Rect>& rectangles)
{
out << '[';
for (auto i = 0u; i<rectangles.size(); ++i)
{
if (i)
out << ',';
out << '[' << rectangles[i].tl().x << ',' << rectangles[i].tl().y << ',' << rectangles[i].br().x << ',' << rectangles[i].br().y << ']';
}
return out << ']';
}
// inputs are x1,y1,x2,y2
constexpr const float inputs[][4] = {{547,432,701,639},{557,435,700,640},{560,438,695,641},{560,438,694,640},{88,443,336,663},{83,444,357,671},{83,444,373,676},{87,449,377,676},{87,454,380,677},{76,453,388,680},{72,447,394,683},{80,437,393,683},{101,430,392,678},{547,433,702,641},{555,433,701,645},{558,437,696,647},{556,440,696,644},{84,443,357,664},{73,448,369,665},{74,449,375,664},{81,451,373,664},{85,454,375,666},{81,454,385,672},{74,452,392,676},{77,445,396,679},{91,433,392,680},{547,430,705,644},{553,429,704,649},{555,434,697,649},{552,438,695,649},{85,445,365,661},{69,451,376,662},{69,452,379,663},{76,453,374,663},{80,452,377,666},{79,451,382,671},{74,449,388,673},{77,445,393,673},{90,434,389,674},{546,429,706,643},{553,428,703,647},{554,432,695,649},{553,435,693,654},{81,445,370,663},{68,454,383,664},{67,455,388,664},{72,454,384,667},{77,452,382,669},{71,448,386,671},{66,443,388,672},{73,438,389,671},{92,429,388,673},{545,429,706,642},{553,429,703,643},{553,432,695,647},{553,432,696,658},{79,450,367,664},{72,459,379,663},{71,459,387,665},{75,458,388,667},{75,455,390,666},{65,448,389,668},{63,441,387,669},{73,433,384,672},{100,425,388,675},{549,429,707,648},{550,429,701,652},{554,434,703,662},{79,462,356,665},{73,462,374,665},{74,461,383,666},{73,460,387,667},{69,457,391,664},{60,447,390,668},{63,435,385,673},{81,430,384,676},{116,433,390,677}};
int main()
{
std::vector<cv::Rect> candidates;
std::transform(std::begin(inputs), std::end(inputs), std::back_inserter(candidates),
[](const float coord[4]) {
return cv::Rect(cv::Point((int)coord[0], (int)coord[1]), cv::Point((int)coord[2], (int)coord[3]));
});
std::cout << "input:\n" << candidates << '\n';
std::vector<int> weights(candidates.size());
cv::groupRectangles(candidates, weights, 3, 0.02);
std::cout << "output:\n" << candidates << '\n';
return EXIT_SUCCESS;
}
测试执行
执行c ++程序时，我得到以下输出：
input:
[[547,432,701,639],[557,435,700,640],[560,438,695,641],[560,438,694,640],[88,443,336,663],[83,444,357,671],[83,444,373,676],[87,449,377,676],[87,454,380,677],[76,453,388,680],[72,447,394,683],[80,437,393,683],[101,430,392,678],[547,433,702,641],[555,433,701,645],[558,437,696,647],[556,440,696,644],[84,443,357,664],[73,448,369,665],[74,449,375,664],[81,451,373,664],[85,454,375,666],[81,454,385,672],[74,452,392,676],[77,445,396,679],[91,433,392,680],[547,430,705,644],[553,429,704,649],[555,434,697,649],[552,438,695,649],[85,445,365,661],[69,451,376,662],[69,452,379,663],[76,453,374,663],[80,452,377,666],[79,451,382,671],[74,449,388,673],[77,445,393,673],[90,434,389,674],[546,429,706,643],[553,428,703,647],[554,432,695,649],[553,435,693,654],[81,445,370,663],[68,454,383,664],[67,455,388,664],[72,454,384,667],[77,452,382,669],[71,448,386,671],[66,443,388,672],[73,438,389,671],[92,429,388,673],[545,429,706,642],[553,429,703,643],[553,432,695,647],[553,432,696,658],[79,450,367,664],[72,459,379,663],[71,459,387,665],[75,458,388,667],[75,455,390,666],[65,448,389,668],[63,441,387,669],[73,433,384,672],[100,425,388,675],[549,429,707,648],[550,429,701,652],[554,434,703,662],[79,462,356,665],[73,462,374,665],[74,461,383,666],[73,460,387,667],[69,457,391,664],[60,447,390,668],[63,435,385,673],[81,430,384,676],[116,433,390,677]]
output:
[[546,431,704,642],[70,447,389,672],[555,435,696,647],[74,455,381,666]]
在python中，我将c ++输入剪切并粘贴为groupRectangles()的输入，但是得到了完全不同的结果：
cv2.groupRectangles([[547,432,701,639],[557,435,700,640],[560,438,695,641],[560,438,694,640],[88,443,336,663],[83,444,357,671],[83,444,373,676],[87,449,377,676],[87,454,380,677],[76,453,388,680],[72,447,394,683],[80,437,393,683],[101,430,392,678],[547,433,702,641],[555,433,701,645],[558,437,696,647],[556,440,696,644],[84,443,357,664],[73,448,369,665],[74,449,375,664],[81,451,373,664],[85,454,375,666],[81,454,385,672],[74,452,392,676],[77,445,396,679],[91,433,392,680],[547,430,705,644],[553,429,704,649],[555,434,697,649],[552,438,695,649],[85,445,365,661],[69,451,376,662],[69,452,379,663],[76,453,374,663],[80,452,377,666],[79,451,382,671],[74,449,388,673],[77,445,393,673],[90,434,389,674],[546,429,706,643],[553,428,703,647],[554,432,695,649],[553,435,693,654],[81,445,370,663],[68,454,383,664],[67,455,388,664],[72,454,384,667],[77,452,382,669],[71,448,386,671],[66,443,388,672],[73,438,389,671],[92,429,388,673],[545,429,706,642],[553,429,703,643],[553,432,695,647],[553,432,696,658],[79,450,367,664],[72,459,379,663],[71,459,387,665],[75,458,388,667],[75,455,390,666],[65,448,389,668],[63,441,387,669],[73,433,384,672],[100,425,388,675],[549,429,707,648],[550,429,701,652],[554,434,703,662],[79,462,356,665],[73,462,374,665],[74,461,383,666],[73,460,387,667],[69,457,391,664],[60,447,390,668],[63,435,385,673],[81,430,384,676],[116,433,390,677]], 3, 0.02)
(array([[553, 433, 700, 647],
[ 75, 449, 382, 669],
[ 95, 430, 390, 676]], dtype=int32), array([[23],
[46],
[ 5]], dtype=int32))
这是我转换为cv::Rect时遇到的问题，groupRectangles()中的不确定性还是其他原因？
答案 0 :(得分：0)
上面的问题完全在python <-> c ++ cv::Rect转换中。在python中，list [4]是x，y，高度，宽度，不是 x1，y1，x2，y2（因为我移植的代码中的一个错误使我相信了）。
如果我更改以下几行，上面的代码将正常工作。
打印时：
out << '[' << rectangles[i].tl().x << ',' << rectangles[i].tl().y << ',' << rectangles[i].width << ',' << rectangles[i].height << ']';
构造cv::Rect时：
return cv::Rect((int)coord[0], (int)coord[1], (int)coord[2], (int)coord[3]);