OpenCV 示例程序 lkdemo

发布于 2024-07-09 11:00:40 字数 985 浏览 11 评论 0原文

参考，OpenCv\samples\c\lkdemo.c

有人知道以下代码片段的作用吗？

从 lkdemo.c Q1 中提取的代码

 for( i = k = 0; i < count; i++ )
            {
                if( add_remove_pt )
                {
                    double dx = pt.x - points[1][i].x;
                    double dy = pt.y - points[1][i].y;

                    if( dx*dx + dy*dy <= 25 )
                    {
                        add_remove_pt = 0;
                        continue;
                    }
                }

                if( !status[i] )
                    continue;

                points[1][k++] = points[1][i];
                cvCircle( image, cvPointFrom32f(points[1][i]), 3, CV_RGB(0,255,0), -1, 8,0);
            }
            count = k;

。

粗线有什么作用？ >>> 点[1][k++] = 点[1][i];

为什么是 k++ ？我很困惑，认为下一点被覆盖了当前点

Q2。

当 cvCircle id 随着帧循环而绘制时，旧点被清除并新点被绘制在哪里？

我期待您的意见。

谢谢=）

原文

reference, OpenCv\samples\c\lkdemo.c

Anybody know what does the following snippet of codes does ?

Code extracted from lkdemo.c

 for( i = k = 0; i < count; i++ )
            {
                if( add_remove_pt )
                {
                    double dx = pt.x - points[1][i].x;
                    double dy = pt.y - points[1][i].y;

                    if( dx*dx + dy*dy <= 25 )
                    {
                        add_remove_pt = 0;
                        continue;
                    }
                }

                if( !status[i] )
                    continue;

                points[1][k++] = points[1][i];
                cvCircle( image, cvPointFrom32f(points[1][i]), 3, CV_RGB(0,255,0), -1, 8,0);
            }
            count = k;

Q1.

What does the bold line does ? >> points[1][k++] = points[1][i];

Why k++ ? I am confuse, thinking that next point is overwritten by
the current point

Q2.

As cvCircle id drawn as the frame loops, where is the old points cleared and new point drawn ?

I look forward to your inputs.

Thanks =)

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南风起 2024-07-16 11:00:40

Q1：

如果我重构代码，也许会有所帮助：

if( status[i] ) {
    points[1][k++] = points[1][i];  // <---- Q1
    cvCircle( image, cvPointFrom32f(points[1][i]), 3, CV_RGB(0,255,0), -1, 8,0);
}

因此，在问题 1 的行中，i 总是递增（通过循环递增），但 k 仅在 status[i] 为 true 时递增。简而言之，它通过复制数组中 status[i] 为 false 的点来消除这些点，然后将数组的长度（计数）设置为 k，即通过消除的数字。

Q1:

Perhaps it would help if I refactor the code:

if( status[i] ) {
    points[1][k++] = points[1][i];  // <---- Q1
    cvCircle( image, cvPointFrom32f(points[1][i]), 3, CV_RGB(0,255,0), -1, 8,0);
}

So in the line for question 1, i always increments (it's incremented by the loop) but k only increments when status[i] is true. In short, it eliminates any points in the array where status[i] is false by copying over them, and then setting the length of the array (count) to k, the number that passed the elimination.

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