vector<Point2f> findCorner(const Mat& img, int idx)
{
stringstream ss;
ss << idx;
string iname = ss.str();
Mat img_gray, d_edges;
Mat line1 = img.clone(), line2 = img.clone(), line3 = img.clone();
Size imgSize = img.size();
cvtColor(img, img_gray, CV_BGR2GRAY);
//GaussianBlur(img_gray, img_gray, Size(3, 3), 0, 0);
// edges detector
Canny(img_gray, d_edges, 50, 300);
imwrite("imgEdge" + iname + ".jpg", d_edges);
vector<Vec2f> lines;
// hough lines detector
HoughLines(d_edges, lines, 1, CV_PI/180, 50);
line1 = drawHoughLines(lines, img);
imwrite("imgSlines" + iname + ".jpg", line1);
VHLINE vh;
vector<Vec2f> vlines, hlines;
vh = divideVHLines(lines);
// sort two directional lines
sort(vh.vlines.begin(), vh.vlines.end(), sortVLines);
sort(vh.hlines.begin(), vh.hlines.end(), sortHLines);
// get unique lines
vlines = groupLines(vh.vlines, imgSize, 15.0);
hlines = groupLines(vh.hlines, imgSize, 15.0);
line2 = drawHoughLines(vlines, img);
line3 = drawHoughLines(hlines, line2);
imwrite("imglines" + iname + ".jpg", line3);
vector<Point2f> corners;
// get two orthogonal lines' intersection as corners
for(size_t i = 0; i < hlines.size(); i++)
{
Point3d hline = getHoughHC(hlines[i]);
for(size_t j = 0; j < vlines.size(); j++)
{
Point3f vline = getHoughHC(vlines[j]);
Point3f corner = vline.cross(hline);
normHC(corner);
corners.push_back(Point2d(corner.x, corner.y));
}
}
// refine corners
cornerSubPix(img_gray, corners, Size(15,15), Size(-1,-1),
TermCriteria(CV_TERMCRIT_ITER+CV_TERMCRIT_EPS, 30, 0.01));
return corners;
}
vector<Vec2f> groupLines(vector<Vec2f> lines, Size imgSize, double minDist)
{
size_t lsize = lines.size();
vector<Vec2f> unilines;
unilines.push_back(lines[0]);
for(size_t i = 1; i < lsize; i++)
{
Vec2f lastline = unilines.back();
Vec2f curline = lines[i];
Point3f unilineHC = getHoughHC(lastline);
Point3f lineHC = getHoughHC(curline);
Point3f crosspt = unilineHC.cross(lineHC);
normHC(crosspt);
// check if two lines intersect in the image
if(crosspt.x >= 0 && crosspt.x < imgSize.width
&& crosspt.y >= 0 && crosspt.y < imgSize.height){
continue;
}
// check if two lines are parallel
int ptype = checkParallel(lineHC, unilineHC);
if(ptype){
double deltaDist = 0;
if(ptype == 1){
deltaDist = abs(lineHC.z/lineHC.x - unilineHC.z/unilineHC.x);
}
if(ptype == 2){
deltaDist = abs(lineHC.z/lineHC.y - unilineHC.z/unilineHC.y);
}
if(ptype == 3){
double k = lineHC.x/unilineHC.x;
double rt = sqrt(lineHC.x*lineHC.x + lineHC.y*lineHC.y);
deltaDist = abs(k*unilineHC.z - lineHC.z)/rt;
}
if(deltaDist <= minDist){
continue;
}
}
// the other cases are unique lines
unilines.push_back(curline);
}
return unilines;
}
