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Chain approximation approximately working

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jaseg 2021-06-02 00:02:36 +02:00
parent 3386e586ac
commit 3b553b3a1d
3 changed files with 34 additions and 13 deletions
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43
svg-flatten/src/nopencv.cpp
View file

@ -156,7 +156,7 @@ void gerbolyze::nopencv::find_blobs(gerbolyze::nopencv::Image32 &img, gerbolyze:
} else if (val_xy >= 1 && img.at_default(x+1, y) == 0) { /* hole border starting point */
nbd += 1;
follow(img, x, y, D_E, nbd, 8, poly);
follow(img, x, y, D_E, nbd, 8, poly); /* FIXME should be 4? */
cb(poly, CP_HOLE);
poly.clear();
}
@ -170,7 +170,8 @@ static size_t region_of_support(Polygon_i poly, size_t i) {
double last_l = 0;
double last_r = 0;
size_t k;
for (k=0; k<sz/2; k++) {
//cerr << "d: ";
for (k=1; k<(sz+1)/2; k++) {
size_t idx1 = (i + k) % sz;
size_t idx2 = (i + sz - k) % sz;
double x1 = poly[idx1][0], y1 = poly[idx1][1], x2 = poly[idx2][0], y2 = poly[idx2][1];
@ -179,17 +180,19 @@ static size_t region_of_support(Polygon_i poly, size_t i) {
* TODO: Check whether distance-to-line is an ok implementation here, the paper asks for distance to chord.
*/
double d = ((x2-x1)*(y1-y0) - (x1-x0)*(y2-y1)) / sqrt(pow(x2-x1, 2) + pow(y2-y1, 2));
//cerr << d << " ";
double r = d/l;
bool cond_a = l < last_l;
bool cond_b = (d > 0) ? (r < last_r) : (r > last_r);
bool cond_b = ((d > 0) && (r < last_r)) || ((d < 0) && (r > last_r));
if (cond_a || cond_b)
if (k > 2 && (cond_a || cond_b))
break;
last_l = l;
last_r = r;
}
//cerr << endl;
k -= 1;
return k;
}
@ -228,7 +231,7 @@ double k_curvature(const Polygon_i &poly, size_t i, size_t k) {
for (size_t idx = 0; idx < k; idx++) {
acc += freeman_angle(poly, (i + 2*sz - idx) % sz) - freeman_angle(poly, (i+idx + 1) % sz);
}
return acc / (2*k);
return acc / k;
}
double k_cos(const Polygon_i &poly, size_t i, size_t k) {
@ -244,15 +247,17 @@ double k_cos(const Polygon_i &poly, size_t i, size_t k) {
return dp / (sqrt(sq_a)*sqrt(sq_b));
}
ContourCallback gerbolyze::nopencv::simplify_contours_teh_chin(int kcos, ContourCallback cb) {
return [&cb, kcos](Polygon_i &poly, ContourPolarity cpol) {
ContourCallback gerbolyze::nopencv::simplify_contours_teh_chin(ContourCallback cb) {
return [&cb](Polygon_i &poly, ContourPolarity cpol) {
size_t sz = poly.size();
vector<size_t> ros(sz);
vector<double> sig(sz);
vector<double> cur(sz);
vector<bool> retain(sz);
for (size_t i=0; i<sz; i++) {
ros[i] = region_of_support(poly, i);
sig[i] = fabs(k_cos(poly, i, kcos));
sig[i] = fabs(k_cos(poly, i, ros[i]));
cur[i] = k_curvature(poly, i, 1);
retain[i] = true;
}
@ -281,9 +286,23 @@ ContourCallback gerbolyze::nopencv::simplify_contours_teh_chin(int kcos, Contour
}
cerr << endl;
/* Pass 0 (like opencv): Remove points with zero 1-curvature */
for (size_t i=0; i<sz; i++) {
if (cur[i] == 0) {
retain[i] = false;
break;
}
}
cerr << "pass 0: ";
for (size_t i=0; i<sz; i++) {
cerr << (retain[i] ? "#" : ".");
}
cerr << endl;
/* 3a, Pass 1: Non-maxima suppression */
for (size_t i=0; i<sz; i++) {
for (size_t j=0; j<ros[i]/2; j++) {
for (size_t j=1; j<ros[i]/2; j++) {
if (sig[i] < sig[(i + j) % sz] || sig[i] < sig[(i + sz - j) % sz]) {
retain[i] = false;
break;
@ -299,8 +318,10 @@ ContourCallback gerbolyze::nopencv::simplify_contours_teh_chin(int kcos, Contour
/* 3b, Pass 2: Zero-curvature suppression */
for (size_t i=0; i<sz; i++) {
if (retain[i] && k_cos(poly, i, kcos) == 0) {
retain[i] = false;
if (retain[i] && ros[i] == 1) {
if (sig[i] <= sig[(i + 1) % sz] || sig[i] <= sig[(i + sz - 1) % sz]) {
retain[i] = false;
}
}
}

2
svg-flatten/src/nopencv.hpp
View file

@ -101,7 +101,7 @@ namespace gerbolyze {
};
void find_blobs(Image32 &img, ContourCallback cb);
ContourCallback simplify_contours_teh_chin(int kcos, ContourCallback cb);
ContourCallback simplify_contours_teh_chin(ContourCallback cb);
}
}

2
svg-flatten/src/nopencv_test.cpp
View file

@ -233,7 +233,7 @@ static void chain_approx_test(const char *fn) {
<< "xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">" << endl;
svg << "<rect width=\"100%\" height=\"100%\" fill=\"black\"/>" << endl;
gerbolyze::nopencv::find_blobs(ref_img, simplify_contours_teh_chin(2, [&svg](Polygon_i &poly, ContourPolarity pol) {
gerbolyze::nopencv::find_blobs(ref_img, simplify_contours_teh_chin([&svg](Polygon_i &poly, ContourPolarity pol) {
svg << "<path fill=\"" << ((pol == CP_HOLE) ? "black" : "white") << "\" d=\"";
svg << "M " << poly[0][0] << " " << poly[0][1];
for (size_t i=1; i<poly.size(); i++) {