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Measurement: Fixed and refactored circle detection:

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- first/last segment of a circular segment was sometimes separated
- circles were sometimes shown where they shouldn't be
This commit is contained in:
Lukas Matena 2022-11-22 09:49:10 +01:00 committed by enricoturri1966
parent 3bdd548358
commit d4ad4aff01
1 changed files with 120 additions and 116 deletions
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236
src/libslic3r/Measure.cpp
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@ -14,17 +14,17 @@ namespace Measure {
constexpr double feature_hover_limit = 0.5; // how close to a feature the mouse must be to highlight it
static std::pair<Vec3d, double> get_center_and_radius(const std::vector<Vec3d>& border, int start_idx, int end_idx, const Transform3d& trafo)
static std::pair<Vec3d, double> get_center_and_radius(const std::vector<Vec3d>& points, const Transform3d& trafo)
{
Vec2ds pts;
Vec2ds out;
double z = 0.;
for (int i=start_idx; i<=end_idx; ++i) {
Vec3d pt_transformed = trafo * border[i];
for (const Vec3d pt : points) {
Vec3d pt_transformed = trafo * pt;
z = pt_transformed.z();
pts.emplace_back(pt_transformed.x(), pt_transformed.y());
out.emplace_back(pt_transformed.x(), pt_transformed.y());
}
auto circle = Geometry::circle_ransac(pts, 20); // FIXME: iterations?
auto circle = Geometry::circle_ransac(out, 20); // FIXME: iterations?
return std::make_pair(trafo.inverse() * Vec3d(circle.center.x(), circle.center.y(), z), circle.radius);
}
@ -216,6 +216,7 @@ void MeasuringImpl::update_planes()
m_planes[plane_id].borders.pop_back();
else {
assert(last_border.front() == last_border.back());
last_border.pop_back();
}
}
}
@ -233,6 +234,9 @@ void MeasuringImpl::update_planes()
void MeasuringImpl::extract_features()
{
auto are_angles_same = [](double a, double b) { return Slic3r::is_approx(a,b); };
auto are_lengths_same = [](double a, double b) { return Slic3r::is_approx(a,b); };
std::vector<double> angles;
std::vector<double> lengths;
@ -246,152 +250,152 @@ void MeasuringImpl::extract_features()
q.setFromTwoVectors(plane.normal, Vec3d::UnitZ());
Transform3d trafo = Transform3d::Identity();
trafo.rotate(q);
for (const std::vector<Vec3d>& border : plane.borders) {
if (border.size() <= 1)
continue;
assert(border.front() == border.back());
int start_idx = -1;
std::vector<SurfaceFeature> edges;
// Given an idx into border, return the index that is idx+offset position,
// while taking into account the need for warp-around and the fact that
// the first and last point are the same.
auto offset_to_index = [border_size = int(border.size())](int idx, int offset) -> int {
assert(std::abs(offset) < border_size);
int out = idx+offset;
if (out >= border_size)
out = out - border_size;
else if (out < 0)
out = border_size + out;
return out;
};
// First calculate angles at all the vertices.
angles.clear();
lengths.clear();
for (int i=0; i<int(border.size()); ++i) { // front is the same as back, hence the weird indexing
const Vec3d& v2 = (i == 0 ? border[0] - border[border.size()-2]
: border[i] - border[i-1]);
const Vec3d& v1 = i == (int)border.size()-1 ? border[1] - border.back()
: border[i+1] - border[i];
int first_different_angle_idx = 0;
for (int i=0; i<int(border.size()); ++i) {
const Vec3d& v2 = border[i] - (i == 0 ? border[border.size()-1] : border[i-1]);
const Vec3d& v1 = (i == int(border.size()-1) ? border[0] : border[i+1]) - border[i];
double angle = atan2(-normal.dot(v1.cross(v2)), -v1.dot(v2)) + M_PI;
if (angle > M_PI)
angle = 2*M_PI - angle;
angles.push_back(angle);
lengths.push_back(v2.norm());
if (first_different_angle_idx == 0 && angles.size() > 1) {
if (! are_angles_same(angles.back(), angles[angles.size()-2]))
first_different_angle_idx = angles.size()-1;
}
}
assert(border.size() == angles.size());
assert(border.size() == lengths.size());
// First go around the border and pick what might be circular segments.
// Save pair of indices to where such potential segments start and end.
// Also remember the length of these segments.
int start_idx = -1;
bool circle = false;
bool first_iter = true;
std::vector<SurfaceFeature> circles;
std::vector<SurfaceFeature> edges;
std::vector<std::pair<int, int>> circles_idxs;
std::vector<double> circles_lengths;
for (int i=1; i<(int)angles.size(); ++i) {
if (Slic3r::is_approx(lengths[i], lengths[i-1])
&& Slic3r::is_approx(angles[i], angles[i-1])
&& i != (int)angles.size()-1 ) {
//std::vector<double> circles_lengths;
std::vector<Vec3d> single_circle; // could be in loop-scope, but reallocations
double single_circle_length = 0.;
int first_pt_idx = offset_to_index(first_different_angle_idx, 1);
int i = first_pt_idx;
while (i != first_pt_idx || first_iter) {
if (are_angles_same(angles[i], angles[offset_to_index(i,-1)])
&& i != offset_to_index(first_pt_idx, -1) // not the last point
&& i != start_idx ) {
// circle
if (! circle) {
circle = true;
start_idx = std::max(0, i-2);
single_circle.clear();
single_circle_length = 0.;
start_idx = offset_to_index(i, -2);
single_circle = { border[start_idx], border[offset_to_index(start_idx,1)] };
single_circle_length += lengths[offset_to_index(i, -1)];
}
single_circle.emplace_back(border[i]);
single_circle_length += lengths[i];
} else {
if (circle) {
const auto& [center, radius] = get_center_and_radius(border, start_idx, i, trafo);
// Add the circle and remember indices into borders.
circles_idxs.emplace_back(start_idx, i);
circles.emplace_back(SurfaceFeature(SurfaceFeatureType::Circle, center, plane.normal, std::nullopt, radius));
circles_lengths.emplace_back(std::accumulate(lengths.begin() + start_idx + 1, lengths.begin() + i + 1, 0.));
circle = false;
}
}
}
if (circle && single_circle.size() >= 5) { // Less than 5 vertices? Not a circle.
single_circle.emplace_back(border[i]);
single_circle_length += lengths[i];
// At this point we might need to merge the first and last segment, if the starting
// point happened to be inside the segment. The discrimination of too small segments
// will follow, so we need a complete picture before that.
if (circles_idxs.size() > 1
&& circles_idxs.back().second == (int)angles.size()-1
&& circles_idxs.front().first == 0) {
// Possibly the same circle. Check that the angle and length criterion holds along the combined segment.
bool same = true;
double last_len = -1.;
double last_angle = 0.;
for (int i=circles_idxs.back().first + 1; i != circles_idxs.front().second; ++i) {
if (i == (int)angles.size())
i = 1;
if (last_len == -1.) {
last_len = lengths[i];
last_angle = angles[i];
} else {
if (! Slic3r::is_approx(lengths[i], last_len) || ! Slic3r::is_approx(angles[i], last_angle)) {
same = false;
break;
bool accept_circle = true;
{
// Check that lengths of internal (!!!) edges match.
int j = offset_to_index(start_idx, 3);
while (j != i) {
if (! are_lengths_same(lengths[offset_to_index(j,-1)], lengths[j])) {
accept_circle = false;
break;
}
j = offset_to_index(j, 1);
}
}
if (accept_circle) {
const auto& [center, radius] = get_center_and_radius(single_circle, trafo);
// Check that the fit went well. The tolerance is high, only to
// reject complete failures.
for (const Vec3d& pt : single_circle) {
if (std::abs((pt - center).norm() - radius) > 0.5) {
accept_circle = false;
break;
}
}
// If the segment subtends less than 90 degrees, throw it away.
accept_circle &= single_circle_length / radius > 0.9*M_PI/2.;
// If this is all-around and 5 to 8 vertices, consider it a polygon.
bool is_polygon = start_idx == i && single_circle.size() <= 9 && single_circle.size() >= 6;
if (accept_circle) {
// Add the circle and remember indices into borders.
circles_idxs.emplace_back(start_idx, i);
if (is_polygon) {
for (int j=0; j<=i; ++j) // No wrap-around handling needed here.
edges.emplace_back(SurfaceFeature(SurfaceFeatureType::Edge,
border[j==0 ? border.size()-1 : j-1], border[j],
std::make_optional(center)));
}
else
circles.emplace_back(SurfaceFeature(SurfaceFeatureType::Circle, center, plane.normal, std::nullopt, radius));
}
}
}
circle = false;
}
if (same) {
// This seems to really be the same circle. Better apply ransac again. The parts can be small and inexact.
std::vector<Vec3d> points(border.begin() + circles_idxs.back().first, border.end());
points.insert(points.end(), border.begin(), border.begin() + circles_idxs.front().second+1);
auto [c, radius] = get_center_and_radius(points, 0, points.size()-1, trafo);
// Now replace the first circle with the combined one, remove the last circle.
// First index of the first circle is saved negative - we are going to pick edges
// from the border later, we will need to know where the merged in segment was.
// The sign simplifies the algorithm that picks the remaining edges - see below.
circles.front() = SurfaceFeature(SurfaceFeatureType::Circle, c, plane.normal, std::nullopt, radius);
circles_idxs.front().first = - circles_idxs.back().first;
circles_lengths.front() += circles_lengths.back();
circles.pop_back();
circles_idxs.pop_back();
circles_lengths.pop_back();
}
}
// Now throw away all circles that subtend less than 90 deg.
assert(circles.size() == circles_lengths.size());
for (int i=0; i<int(circles.size()); ++i) {
double r = std::get<1>(circles[i].get_circle());
if (circles_lengths[i] / r < 0.9*M_PI/2.) {
circles_lengths.erase(circles_lengths.begin() + i);
circles.erase(circles.begin() + i);
circles_idxs.erase(circles_idxs.begin() + i);
--i;
}
// Take care of the wrap around.
first_iter = false;
i = offset_to_index(i, 1);
}
circles_lengths.clear(); // no longer needed, make it obvious
// Anything under 5 vertices shall not be considered a circle.
assert(circles_idxs.size() == circles.size());
for (int i=int(circles_idxs.size())-1; i>=0; --i) {
const auto& [start, end] = circles_idxs[i];
int N = start >= 0
? end - start + (start == 0 && end == (int)border.size()-1 ? 0 : 1) // last point is the same as first
: end + (border.size() + start);
if (N < 5) {
circles.erase(circles.begin() + i);
circles_idxs.erase(circles_idxs.begin() + i);
} else if (N <= 8 && start == 0 && end == (int)border.size()-1) {
// This is a regular 5-8 polygon. Add the edges as edges with a special
// point and remove the circle. Leave the indices in circles_idxs, so
// the edges are not picked up again later.
const Vec3d center = std::get<0>(circles[i].get_circle());
for (int j=1; j<=end; ++j)
edges.emplace_back(SurfaceFeature(SurfaceFeatureType::Edge,
border[j - 1], border[j], std::make_optional(center)));
circles.erase(circles.begin() + i);
}
}
// We have the circles. Now go around again and pick edges, while jumping over circles.
// If the first index of the first circle is negative, it means that it was merged
// with a segment that was originally at the back and is no longer there. Ressurect
// its pair of indices so that edges are not picked again.
if (! circles_idxs.empty() && circles_idxs.front().first < 0)
circles_idxs.emplace_back(-circles_idxs.front().first, int(border.size()));
int cidx = 0; // index of next circle to jump over
for (int i=1; i<int(border.size()); ++i) {
if (cidx < (int)circles_idxs.size() && i > (int)circles_idxs[cidx].first)
i = circles_idxs[cidx++].second;
else
edges.emplace_back(SurfaceFeature(SurfaceFeatureType::Edge, border[i - 1], border[i]));
if (circles_idxs.empty()) {
// Just add all edges.
for (int i=1; i<int(border.size()); ++i)
edges.emplace_back(SurfaceFeature(SurfaceFeatureType::Edge, border[i-1], border[i]));
edges.emplace_back(SurfaceFeature(SurfaceFeatureType::Edge, border[0], border[border.size()-1]));
} else {
// There is at least one circular segment. Start at its end and add edges until the start of the next one.
int i = circles_idxs.front().second;
int circle_idx = 1;
while (true) {
i = offset_to_index(i, 1);
edges.emplace_back(SurfaceFeature(SurfaceFeatureType::Edge, border[offset_to_index(i,-1)], border[i]));
if (circle_idx < int(circles_idxs.size()) && i == circles_idxs[circle_idx].first) {
i = circles_idxs[circle_idx].second;
++circle_idx;
}
if (i == circles_idxs.front().first)
break;
}
}
// Merge adjacent edges where needed.