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fix choose minimum angle in rotatingCalipers

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This commit is contained in:
AleksandrPanov 2021-08-11 19:08:52 +03:00
parent 992b47b991
commit 8199967b31
1 changed files with 34 additions and 21 deletions
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55
modules/imgproc/src/rotcalipers.cpp
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@ -88,6 +88,32 @@ enum { CALIPERS_MAXHEIGHT=0, CALIPERS_MINAREARECT=1, CALIPERS_MAXDIST=2 };
// Notes:
//F*/
static void rotate90CCW(const cv::Point2f& in, cv::Point2f &out)
{
out.x = -in.y;
out.y = in.x;
}
static void rotate90CW(const cv::Point2f& in, cv::Point2f &out)
{
out.x = in.y;
out.y = -in.x;
}
static void rotate180(const cv::Point2f& in, cv::Point2f &out)
{
out.x = -in.x;
out.y = -in.y;
}
/* return true if first vector is to the right (clockwise) of the second */
static bool firstVecIsRight(const cv::Point2f& vec1, const cv::Point2f &vec2)
{
cv::Point2f tmp;
rotate90CW(vec1, tmp);
return tmp.x * vec2.x + tmp.y * vec2.y < 0;
}
/* we will use usual cartesian coordinates */
static void rotatingCalipers( const Point2f* points, int n, int mode, float* out )
{
@ -100,6 +126,7 @@ static void rotatingCalipers( const Point2f* points, int n, int mode, float* out
Point2f* vect = (Point2f*)(inv_vect_length + n);
int left = 0, bottom = 0, right = 0, top = 0;
int seq[4] = { -1, -1, -1, -1 };
Point2f rot_vect[4];
/* rotating calipers sides will always have coordinates
(a,b) (-b,a) (-a,-b) (b, -a)
@ -179,32 +206,18 @@ static void rotatingCalipers( const Point2f* points, int n, int mode, float* out
/* all of edges will be checked while rotating calipers by 90 degrees */
for( k = 0; k < n; k++ )
{
/* sinus of minimal angle */
/*float sinus;*/
/* compute cosine of angle between calipers side and polygon edge */
/* dp - dot product */
float dp[4] = {
+base_a * vect[seq[0]].x + base_b * vect[seq[0]].y,
-base_b * vect[seq[1]].x + base_a * vect[seq[1]].y,
-base_a * vect[seq[2]].x - base_b * vect[seq[2]].y,
+base_b * vect[seq[3]].x - base_a * vect[seq[3]].y,
};
float maxcos = dp[0] * inv_vect_length[seq[0]];
/* number of calipers edges, that has minimal angle with edge */
int main_element = 0;
/* choose minimal angle */
for ( i = 1; i < 4; ++i )
/* choose minimum angle between calipers side and polygon edge by dot product sign */
rot_vect[0] = vect[seq[0]];
rotate90CW(vect[seq[1]], rot_vect[1]);
rotate180(vect[seq[2]], rot_vect[2]);
rotate90CCW(vect[seq[3]], rot_vect[3]);
for (i = 1; i < 4; i++)
{
float cosalpha = dp[i] * inv_vect_length[seq[i]];
if (cosalpha > maxcos)
{
if (firstVecIsRight(rot_vect[i], rot_vect[main_element]))
main_element = i;
maxcos = cosalpha;
}
}
/*rotate calipers*/