//函数功能：利用RANSAC算法从图像中提取直线，RANSAC对噪声敏感度小
//输入：二值化图像input，目标直线的一个端点center
//输出：目标直线方程
public line doRANSAC(myPicture input, myPair center)
{
LinkedList <myPair> arr = new LinkedList <myPair>();
for (int i = 0; i < input.width; ++i)
{
for (int j = 0; j < input.height; ++j)
{
if (input.grayDegree[i, j] == 255)
{
arr.AddLast(new myPair(i, j));
}
}
}
Random rd = new Random(13);
line ret = new line(0, 0, 0);
double besterror = 1000000000000;
int bound = (int)(0.07 * arr.Count);
for (int iter = 0; iter < 100; ++iter)
{
int sampleIndex = rd.Next() % arr.Count;
myPair sample = arr.ElementAt(sampleIndex);
line cur = new line(center, sample);
LinkedList <myPair> alsoinliers = new LinkedList <myPair>();
foreach (myPair p in arr)
{
double d = cur.distance(p);
if (d <= 4)
{
alsoinliers.AddLast(p);
}
}
if (alsoinliers.Count >= bound)
{
alsoinliers.AddLast(sample);
line better = calLine(alsoinliers);
double thiserror = 0;
foreach (myPair p in alsoinliers)
{
double dis = better.distance(p);
thiserror += dis * dis;
}
thiserror /= alsoinliers.Count;
if (thiserror < besterror)
{
besterror = thiserror;
ret = better;
}
}
}
return(ret);
/*
* for (int i = 0; i < input.width; ++i)
* {
* for (int j = 0; j < input.height; ++j)
* {
* double val = Math.Abs(ret.A * i + ret.B * j + ret.C);
* if (val <= 1)
* {
* input.picture.SetPixel(i, j, Color.FromArgb(255, 0, 0));
* }
* }
* }
*/
//return input;
}
//函数功能：确定仪表盘指针的方向向量
//输入：二值图像input，直线方程ret，仪表盘中心o
//输出：仪表盘指针上的某一个点
public myPair doFind(myPicture input, line ret, circle o)
{
if (Math.Abs(ret.B) < 0.000001)
{
return(new myPair((int)o.x, 0));
}
int MAGIC = (int)(input.width * 0.18);
int cnt1 = 0, cnt2 = 0;
double K = -ret.A / ret.B;
double B = -ret.C / ret.B;
for (int dx = 1; dx <= MAGIC; ++dx)
{
double x = o.x + dx;
double y = K * x + B;
int xx = (int)x;
int yy = (int)y;
if (xx + 2 >= input.width || xx - 2 < 0)
{
break;
}
if (yy + 2 >= input.height || yy - 2 < 0)
{
break;
}
for (int i = -2; i <= 2; ++i)
{
for (int j = -2; j <= 2; ++j)
{
if (input.grayDegree[(int)(x + i), (int)(y + j)] == 255)
{
cnt1++;
}
}
}
}
for (int dx = 1; dx <= MAGIC; ++dx)
{
double x = o.x - dx;
double y = K * x + B;
int xx = (int)x;
int yy = (int)y;
if (xx + 2 >= input.width || xx - 2 < 0)
{
break;
}
if (yy + 2 >= input.height || yy - 2 < 0)
{
break;
}
for (int i = -2; i <= 2; ++i)
{
for (int j = -2; j <= 2; ++j)
{
if (input.grayDegree[(int)(x + i), (int)(y + j)] == 255)
{
cnt2++;
}
}
}
}
if (cnt1 > cnt2)
{
double x = o.x + MAGIC;
double y = K * x + B;
return(new myPair((int)x, (int)y));
}
else
{
double x = o.x - MAGIC;
double y = K * x + B;
return(new myPair((int)x, (int)y));
}
}
