标签:triangle area int iou 计算 y1 x3 y3 车位
车位检测中,判断多帧图像检测出的车位是否是同一个车位.计算其IOU.
判断一个点是否在一个四边形内
Approach : Let the coordinates of four corners be A(x1, y1), B(x2, y2), C(x3, y3) and D(x4, y4). And coordinates of the given point P be (x, y)
- Calculate area of the given rectangle, i.e., area of the rectangle ABCD as area of triangle ABC + area of triangle ACD.
Area A = [ x1(y2 – y3) + x2(y3 – y1) + x3(y1-y2)]/2 + [ x1(y4 – y3) + x4(y3 – y1) + x3(y1-y4)]/2 - Calculate area of the triangle PAB as A1.
- Calculate area of the triangle PBC as A2.
- Calculate area of the triangle PCD as A3.
- Calculate area of the triangle PAD as A4.
- If P lies inside the triangle, then A1 + A2 + A3 + A4 must be equal to A.
#include <bits/stdc++.h>
using namespace std;
/* A utility function to calculate area of
triangle formed by (x1, y1), (x2, y2) and
(x3, y3) */
float area(int x1, int y1, int x2, int y2,
int x3, int y3)
{
return abs((x1 * (y2 - y3) + x2 * (y3 - y1) +
x3 * (y1 - y2)) / 2.0);
}
/* A function to check whether point P(x, y)
lies inside the rectangle formed by A(x1, y1),
B(x2, y2), C(x3, y3) and D(x4, y4) */
bool check(int x1, int y1, int x2, int y2, int x3,
int y3, int x4, int y4, int x, int y)
{
/* Calculate area of rectangle ABCD */
float A = area(x1, y1, x2, y2, x3, y3) +
area(x1, y1, x4, y4, x3, y3);
/* Calculate area of triangle PAB */
float A1 = area(x, y, x1, y1, x2, y2);
/* Calculate area of triangle PBC */
float A2 = area(x, y, x2, y2, x3, y3);
/* Calculate area of triangle PCD */
float A3 = area(x, y, x3, y3, x4, y4);
/* Calculate area of triangle PAD */
float A4 = area(x, y, x1, y1, x4, y4);
/* Check if sum of A1, A2, A3 and A4
is same as A */
return (A == A1 + A2 + A3 + A4);
}
/* Driver program to test above function */
int main()
{
/* Let us check whether the point P(10, 15)
lies inside the rectangle formed by A(0, 10),
B(10, 0) C(0, -10) D(-10, 0) */
if (check(0, 10, 10, 0, 0, -10, -10, 0, 10, 15))
cout << "yes";
else
cout << "no";
return 0;
}
标签:triangle,area,int,iou,计算,y1,x3,y3,车位 来源: https://www.cnblogs.com/sdu20112013/p/10919352.html
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