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opencv/modules/imgproc/src/rotcalipers.cpp
Andrey Kamaev 2a6fb2867e Remove all using directives for STL namespace and members 
Made all STL usages explicit to be able automatically find all usages of
particular class or function.
2013-02-25 15:04:17 +04:00

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/*M///////////////////////////////////////////////////////////////////////////////////////
//
// IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
//
// By downloading, copying, installing or using the software you agree to this license.
// If you do not agree to this license, do not download, install,
// copy or use the software.
//
//
// License Agreement
// For Open Source Computer Vision Library
//
// Copyright (C) 2000, Intel Corporation, all rights reserved.
// Third party copyrights are property of their respective owners.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
// * Redistribution's of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// * Redistribution's in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * The name of OpenCV Foundation may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// This software is provided by the copyright holders and contributors "as is" and
// any express or implied warranties, including, but not limited to, the implied
// warranties of merchantability and fitness for a particular purpose are disclaimed.
// In no event shall the OpenCV Foundation or contributors be liable for any direct,
// indirect, incidental, special, exemplary, or consequential damages
// (including, but not limited to, procurement of substitute goods or services;
// loss of use, data, or profits; or business interruption) however caused
// and on any theory of liability, whether in contract, strict liability,
// or tort (including negligence or otherwise) arising in any way out of
// the use of this software, even if advised of the possibility of such damage.
//
//M*/
#include "precomp.hpp"
namespace cv
{
struct MinAreaState
{
int bottom;
int left;
float height;
float width;
float base_a;
float base_b;
};
enum { CALIPERS_MAXHEIGHT=0, CALIPERS_MINAREARECT=1, CALIPERS_MAXDIST=2 };
/*F///////////////////////////////////////////////////////////////////////////////////////
// Name: rotatingCalipers
// Purpose:
// Rotating calipers algorithm with some applications
//
// Context:
// Parameters:
// points - convex hull vertices ( any orientation )
// n - number of vertices
// mode - concrete application of algorithm
// can be CV_CALIPERS_MAXDIST or
// CV_CALIPERS_MINAREARECT
// left, bottom, right, top - indexes of extremal points
// out - output info.
// In case CV_CALIPERS_MAXDIST it points to float value -
// maximal height of polygon.
// In case CV_CALIPERS_MINAREARECT
// ((CvPoint2D32f*)out)[0] - corner
// ((CvPoint2D32f*)out)[1] - vector1
// ((CvPoint2D32f*)out)[0] - corner2
//
// ^
// |
// vector2 |
// |
// |____________\
// corner /
// vector1
//
// Returns:
// Notes:
//F*/
/* we will use usual cartesian coordinates */
static void rotatingCalipers( const Point2f* points, int n, int mode, float* out )
{
float minarea = FLT_MAX;
float max_dist = 0;
char buffer[32] = {};
int i, k;
AutoBuffer<float> abuf(n*3);
float* inv_vect_length = abuf;
Point2f* vect = (Point2f*)(inv_vect_length + n);
int left = 0, bottom = 0, right = 0, top = 0;
int seq[4] = { -1, -1, -1, -1 };
/* rotating calipers sides will always have coordinates
(a,b) (-b,a) (-a,-b) (b, -a)
*/
/* this is a first base bector (a,b) initialized by (1,0) */
float orientation = 0;
float base_a;
float base_b = 0;
float left_x, right_x, top_y, bottom_y;
Point2f pt0 = points[0];
left_x = right_x = pt0.x;
top_y = bottom_y = pt0.y;
for( i = 0; i < n; i++ )
{
double dx, dy;
if( pt0.x < left_x )
left_x = pt0.x, left = i;
if( pt0.x > right_x )
right_x = pt0.x, right = i;
if( pt0.y > top_y )
top_y = pt0.y, top = i;
if( pt0.y < bottom_y )
bottom_y = pt0.y, bottom = i;
Point2f pt = points[(i+1) & (i+1 < n ? -1 : 0)];
dx = pt.x - pt0.x;
dy = pt.y - pt0.y;
vect[i].x = (float)dx;
vect[i].y = (float)dy;
inv_vect_length[i] = (float)(1./std::sqrt(dx*dx + dy*dy));
pt0 = pt;
}
// find convex hull orientation
{
double ax = vect[n-1].x;
double ay = vect[n-1].y;
for( i = 0; i < n; i++ )
{
double bx = vect[i].x;
double by = vect[i].y;
double convexity = ax * by - ay * bx;
if( convexity != 0 )
{
orientation = (convexity > 0) ? 1.f : (-1.f);
break;
}
ax = bx;
ay = by;
}
CV_Assert( orientation != 0 );
}
base_a = orientation;
/*****************************************************************************************/
/* init calipers position */
seq[0] = bottom;
seq[1] = right;
seq[2] = top;
seq[3] = left;
/*****************************************************************************************/
/* Main loop - evaluate angles and rotate calipers */
/* 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 dp0 = base_a * vect[seq[0]].x + base_b * vect[seq[0]].y;
float dp1 = -base_b * vect[seq[1]].x + base_a * vect[seq[1]].y;
float dp2 = -base_a * vect[seq[2]].x - base_b * vect[seq[2]].y;
float dp3 = base_b * vect[seq[3]].x - base_a * vect[seq[3]].y;
float cosalpha = dp0 * inv_vect_length[seq[0]];
float maxcos = cosalpha;
/* number of calipers edges, that has minimal angle with edge */
int main_element = 0;
/* choose minimal angle */
cosalpha = dp1 * inv_vect_length[seq[1]];
maxcos = (cosalpha > maxcos) ? (main_element = 1, cosalpha) : maxcos;
cosalpha = dp2 * inv_vect_length[seq[2]];
maxcos = (cosalpha > maxcos) ? (main_element = 2, cosalpha) : maxcos;
cosalpha = dp3 * inv_vect_length[seq[3]];
maxcos = (cosalpha > maxcos) ? (main_element = 3, cosalpha) : maxcos;
/*rotate calipers*/
{
//get next base
int pindex = seq[main_element];
float lead_x = vect[pindex].x*inv_vect_length[pindex];
float lead_y = vect[pindex].y*inv_vect_length[pindex];
switch( main_element )
{
case 0:
base_a = lead_x;
base_b = lead_y;
break;
case 1:
base_a = lead_y;
base_b = -lead_x;
break;
case 2:
base_a = -lead_x;
base_b = -lead_y;
break;
case 3:
base_a = -lead_y;
base_b = lead_x;
break;
default:
CV_Error(CV_StsError, "main_element should be 0, 1, 2 or 3");
}
}
/* change base point of main edge */
seq[main_element] += 1;
seq[main_element] = (seq[main_element] == n) ? 0 : seq[main_element];
switch (mode)
{
case CALIPERS_MAXHEIGHT:
{
/* now main element lies on edge alligned to calipers side */
/* find opposite element i.e. transform */
/* 0->2, 1->3, 2->0, 3->1 */
int opposite_el = main_element ^ 2;
float dx = points[seq[opposite_el]].x - points[seq[main_element]].x;
float dy = points[seq[opposite_el]].y - points[seq[main_element]].y;
float dist;
if( main_element & 1 )
dist = (float)fabs(dx * base_a + dy * base_b);
else
dist = (float)fabs(dx * (-base_b) + dy * base_a);
if( dist > max_dist )
max_dist = dist;
}
break;
case CALIPERS_MINAREARECT:
/* find area of rectangle */
{
float height;
float area;
/* find vector left-right */
float dx = points[seq[1]].x - points[seq[3]].x;
float dy = points[seq[1]].y - points[seq[3]].y;
/* dotproduct */
float width = dx * base_a + dy * base_b;
/* find vector left-right */
dx = points[seq[2]].x - points[seq[0]].x;
dy = points[seq[2]].y - points[seq[0]].y;
/* dotproduct */
height = -dx * base_b + dy * base_a;
area = width * height;
if( area <= minarea )
{
float *buf = (float *) buffer;
minarea = area;
/* leftist point */
((int *) buf)[0] = seq[3];
buf[1] = base_a;
buf[2] = width;
buf[3] = base_b;
buf[4] = height;
/* bottom point */
((int *) buf)[5] = seq[0];
buf[6] = area;
}
}
break;
} /*switch */
} /* for */
switch (mode)
{
case CALIPERS_MINAREARECT:
{
float *buf = (float *) buffer;
float A1 = buf[1];
float B1 = buf[3];
float A2 = -buf[3];
float B2 = buf[1];
float C1 = A1 * points[((int *) buf)[0]].x + points[((int *) buf)[0]].y * B1;
float C2 = A2 * points[((int *) buf)[5]].x + points[((int *) buf)[5]].y * B2;
float idet = 1.f / (A1 * B2 - A2 * B1);
float px = (C1 * B2 - C2 * B1) * idet;
float py = (A1 * C2 - A2 * C1) * idet;
out[0] = px;
out[1] = py;
out[2] = A1 * buf[2];
out[3] = B1 * buf[2];
out[4] = A2 * buf[4];
out[5] = B2 * buf[4];
}
break;
case CALIPERS_MAXHEIGHT:
{
out[0] = max_dist;
}
break;
}
}
}
cv::RotatedRect cv::minAreaRect( InputArray _points )
{
Mat hull;
Point2f out[3];
RotatedRect box;
convexHull(_points, hull, true, true);
if( hull.depth() != CV_32F )
{
Mat temp;
hull.convertTo(temp, CV_32F);
hull = temp;
}
int n = hull.checkVector(2);
const Point2f* hpoints = (const Point2f*)hull.data;
if( n > 2 )
{
rotatingCalipers( hpoints, n, CALIPERS_MINAREARECT, (float*)out );
box.center.x = out[0].x + (out[1].x + out[2].x)*0.5f;
box.center.y = out[0].y + (out[1].y + out[2].y)*0.5f;
box.size.width = (float)std::sqrt((double)out[1].x*out[1].x + (double)out[1].y*out[1].y);
box.size.height = (float)std::sqrt((double)out[2].x*out[2].x + (double)out[2].y*out[2].y);
box.angle = (float)atan2( (double)out[1].y, (double)out[1].x );
}
else if( n == 2 )
{
box.center.x = (hpoints[0].x + hpoints[1].x)*0.5f;
box.center.y = (hpoints[0].y + hpoints[1].y)*0.5f;
double dx = hpoints[1].x - hpoints[0].x;
double dy = hpoints[1].y - hpoints[0].y;
box.size.width = (float)std::sqrt(dx*dx + dy*dy);
box.size.height = 0;
box.angle = (float)atan2( dy, dx );
}
else
{
if( n == 1 )
box.center = hpoints[0];
}
box.angle = (float)(box.angle*180/CV_PI);
return box;
}
CV_IMPL CvBox2D
cvMinAreaRect2( const CvArr* array, CvMemStorage* /*storage*/ )
{
cv::AutoBuffer<double> abuf;
cv::Mat points = cv::cvarrToMat(array, false, false, 0, &abuf);
cv::RotatedRect rr = cv::minAreaRect(points);
return (CvBox2D)rr;
}
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