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42 #include "precomp.hpp"
50 //#define _SUBPIX_VERBOSE
57 void drawCircles(Mat& img, const vector<Point2f>& corners, const vector<float>& radius)
59 for(size_t i = 0; i < corners.size(); i++)
61 circle(img, corners[i], cvRound(radius[i]), CV_RGB(255, 0, 0));
65 int histQuantile(const Mat& hist, float quantile)
67 if(hist.dims > 1) return -1; // works for 1D histograms only
70 float total_sum = (float)sum(hist).val[0];
71 float quantile_sum = total_sum*quantile;
72 for(int j = 0; j < hist.size[0]; j++)
74 cur_sum += (float)hist.at<float>(j);
75 if(cur_sum > quantile_sum)
81 return hist.size[0] - 1;
84 bool is_smaller(const std::pair<int, float>& p1, const std::pair<int, float>& p2)
86 return p1.second < p2.second;
89 void orderContours(const vector<vector<Point> >& contours, Point2f point, vector<std::pair<int, float> >& order)
92 size_t i, j, n = contours.size();
93 for(i = 0; i < n; i++)
95 size_t ni = contours[i].size();
96 double min_dist = std::numeric_limits<double>::max();
97 for(j = 0; j < ni; j++)
99 double dist = norm(Point2f((float)contours[i][j].x, (float)contours[i][j].y) - point);
100 min_dist = MIN(min_dist, dist);
102 order.push_back(std::pair<int, float>((int)i, (float)min_dist));
105 std::sort(order.begin(), order.end(), is_smaller);
108 // fit second order curve to a set of 2D points
109 void fitCurve2Order(const vector<Point2f>& /*points*/, vector<float>& /*curve*/)
114 void findCurvesCross(const vector<float>& /*curve1*/, const vector<float>& /*curve2*/, Point2f& /*cross_point*/)
118 void findLinesCrossPoint(Point2f origin1, Point2f dir1, Point2f origin2, Point2f dir2, Point2f& cross_point)
120 float det = dir2.x*dir1.y - dir2.y*dir1.x;
121 Point2f offset = origin2 - origin1;
123 float alpha = (dir2.x*offset.y - dir2.y*offset.x)/det;
124 cross_point = origin1 + dir1*alpha;
127 void findCorner(const vector<Point>& contour, Point2f point, Point2f& corner)
129 // find the nearest point
130 double min_dist = std::numeric_limits<double>::max();
134 for(size_t i = 0; i < contour.size(); i++)
136 double dist = norm(Point2f((float)contour[i].x, (float)contour[i].y) - point);
143 assert(min_idx >= 0);
145 // temporary solution, have to make something more precise
146 corner = contour[min_idx];
150 void findCorner(const vector<Point2f>& contour, Point2f point, Point2f& corner)
152 // find the nearest point
153 double min_dist = std::numeric_limits<double>::max();
157 for(size_t i = 0; i < contour.size(); i++)
159 double dist = norm(contour[i] - point);
166 assert(min_idx >= 0);
168 // temporary solution, have to make something more precise
169 corner = contour[min_idx];
173 int segment_hist_max(const Mat& hist, int& low_thresh, int& high_thresh)
176 //const double max_bell_width = 20; // we expect two bells with width bounded above
177 //const double min_bell_width = 5; // and below
179 double total_sum = sum(hist).val[0];
180 //double thresh = total_sum/(2*max_bell_width)*0.25f; // quarter of a bar inside a bell
182 // threshold(hist, bw, thresh, 255.0, CV_THRESH_BINARY);
184 double quantile_sum = 0.0;
185 //double min_quantile = 0.2;
187 double max_segment_length = 0;
188 int max_start_x = -1;
191 const double out_of_bells_fraction = 0.1;
192 for(int x = 0; x < hist.size[0]; x++)
194 quantile_sum += hist.at<float>(x);
195 if(quantile_sum < 0.2*total_sum) continue;
197 if(quantile_sum - low_sum > out_of_bells_fraction*total_sum)
199 if(max_segment_length < x - start_x)
201 max_segment_length = x - start_x;
202 max_start_x = start_x;
206 low_sum = quantile_sum;
217 low_thresh = cvRound(max_start_x + 0.25*(max_end_x - max_start_x));
218 high_thresh = cvRound(max_start_x + 0.75*(max_end_x - max_start_x));
225 bool cv::find4QuadCornerSubpix(InputArray _img, InputOutputArray _corners, Size region_size)
227 Mat img = _img.getMat(), cornersM = _corners.getMat();
228 int ncorners = cornersM.checkVector(2, CV_32F);
229 CV_Assert( ncorners >= 0 );
230 Point2f* corners = cornersM.ptr<Point2f>();
231 const int nbins = 256;
232 float ranges[] = {0, 256};
233 const float* _ranges = ranges;
236 #if defined(_SUBPIX_VERBOSE)
237 vector<float> radius;
238 radius.assign(corners.size(), 0.0f);
239 #endif //_SUBPIX_VERBOSE
242 Mat black_comp, white_comp;
243 for(int i = 0; i < ncorners; i++)
246 Rect roi(cvRound(corners[i].x - region_size.width), cvRound(corners[i].y - region_size.height),
247 region_size.width*2 + 1, region_size.height*2 + 1);
248 Mat img_roi = img(roi);
249 calcHist(&img_roi, 1, &channels, Mat(), hist, 1, &nbins, &_ranges);
252 int black_thresh = histQuantile(hist, 0.45f);
253 int white_thresh = histQuantile(hist, 0.55f);
255 int black_thresh, white_thresh;
256 segment_hist_max(hist, black_thresh, white_thresh);
259 threshold(img, black_comp, black_thresh, 255.0, CV_THRESH_BINARY_INV);
260 threshold(img, white_comp, white_thresh, 255.0, CV_THRESH_BINARY);
262 const int erode_count = 1;
263 erode(black_comp, black_comp, Mat(), Point(-1, -1), erode_count);
264 erode(white_comp, white_comp, Mat(), Point(-1, -1), erode_count);
266 #if defined(_SUBPIX_VERBOSE)
267 namedWindow("roi", 1);
268 imshow("roi", img_roi);
269 imwrite("test.jpg", img);
270 namedWindow("black", 1);
271 imshow("black", black_comp);
272 namedWindow("white", 1);
273 imshow("white", white_comp);
275 imwrite("black.jpg", black_comp);
276 imwrite("white.jpg", white_comp);
280 vector<vector<Point> > white_contours, black_contours;
281 vector<Vec4i> white_hierarchy, black_hierarchy;
282 findContours(black_comp, black_contours, black_hierarchy, CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE);
283 findContours(white_comp, white_contours, white_hierarchy, CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE);
285 if(black_contours.size() < 5 || white_contours.size() < 5) continue;
287 // find two white and black blobs that are close to the input point
288 vector<std::pair<int, float> > white_order, black_order;
289 orderContours(black_contours, corners[i], black_order);
290 orderContours(white_contours, corners[i], white_order);
292 const float max_dist = 10.0f;
293 if(black_order[0].second > max_dist || black_order[1].second > max_dist ||
294 white_order[0].second > max_dist || white_order[1].second > max_dist)
296 continue; // there will be no improvement in this corner position
299 const vector<Point>* quads[4] = {&black_contours[black_order[0].first], &black_contours[black_order[1].first],
300 &white_contours[white_order[0].first], &white_contours[white_order[1].first]};
301 vector<Point2f> quads_approx[4];
302 Point2f quad_corners[4];
303 for(int k = 0; k < 4; k++)
306 vector<Point2f> temp;
307 for(size_t j = 0; j < quads[k]->size(); j++) temp.push_back((*quads[k])[j]);
308 approxPolyDP(Mat(temp), quads_approx[k], 0.5, true);
310 findCorner(quads_approx[k], corners[i], quad_corners[k]);
312 findCorner(*quads[k], corners[i], quad_corners[k]);
314 quad_corners[k] += Point2f(0.5f, 0.5f);
318 Point2f origin1 = quad_corners[0];
319 Point2f dir1 = quad_corners[1] - quad_corners[0];
320 Point2f origin2 = quad_corners[2];
321 Point2f dir2 = quad_corners[3] - quad_corners[2];
322 double angle = acos(dir1.dot(dir2)/(norm(dir1)*norm(dir2)));
323 if(cvIsNaN(angle) || cvIsInf(angle) || angle < 0.5 || angle > CV_PI - 0.5) continue;
325 findLinesCrossPoint(origin1, dir1, origin2, dir2, corners[i]);
327 #if defined(_SUBPIX_VERBOSE)
328 radius[i] = norm(corners[i] - ground_truth_corners[ground_truth_idx])*6;
331 Mat test(img.size(), CV_32FC3);
332 cvtColor(img, test, CV_GRAY2RGB);
333 // line(test, quad_corners[0] - corners[i] + Point2f(30, 30), quad_corners[1] - corners[i] + Point2f(30, 30), cvScalar(0, 255, 0));
334 // line(test, quad_corners[2] - corners[i] + Point2f(30, 30), quad_corners[3] - corners[i] + Point2f(30, 30), cvScalar(0, 255, 0));
335 vector<vector<Point> > contrs;
337 for(int k = 0; k < 4; k++)
339 //contrs[0] = quads_approx[k];
341 for(size_t j = 0; j < quads_approx[k].size(); j++) contrs[0].push_back(quads_approx[k][j]);
342 drawContours(test, contrs, 0, CV_RGB(0, 0, 255), 1, 1, vector<Vec4i>(), 2);
343 circle(test, quad_corners[k], 0.5, CV_RGB(255, 0, 0));
345 Mat test1 = test(Rect(corners[i].x - 30, corners[i].y - 30, 60, 60));
348 imwrite("test.jpg", test);
351 #endif //_SUBPIX_VERBOSE
355 #if defined(_SUBPIX_VERBOSE)
356 Mat test(img.size(), CV_32FC3);
357 cvtColor(img, test, CV_GRAY2RGB);
358 drawCircles(test, corners, radius);
360 namedWindow("corners", 1);
361 imshow("corners", test);
363 #endif //_SUBPIX_VERBOSE