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refactor to use covariance to best estimate XY variance of the connection and thus second moment of area

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This commit is contained in:
PavelMikus 2022-07-27 11:29:31 +02:00
parent 9cfde724f1
commit dbe864ea8a
1 changed files with 79 additions and 20 deletions
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99
src/libslic3r/SupportSpotsGenerator.cpp
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@ -15,6 +15,7 @@
#include "libslic3r/ClipperUtils.hpp"
#include "Geometry/ConvexHull.hpp"
#define DETAILED_DEBUG_LOGS
#define DEBUG_FILES
#ifdef DEBUG_FILES
@ -252,21 +253,25 @@ struct IslandConnection {
float area { };
Vec3f centroid_accumulator = Vec3f::Zero();
Vec2f second_moment_of_area_accumulator = Vec2f::Zero();
float second_moment_of_area_covariance_accumulator { };
void add(const IslandConnection &other) {
this->area += other.area;
this->centroid_accumulator += other.centroid_accumulator;
this->second_moment_of_area_accumulator += other.second_moment_of_area_accumulator;
this->second_moment_of_area_covariance_accumulator += other.second_moment_of_area_covariance_accumulator;
}
void print_info(const std::string &tag) {
Vec3f centroid = centroid_accumulator / area;
Vec2f variance =
(second_moment_of_area_accumulator / area - centroid.head<2>().cwiseProduct(centroid.head<2>()));
float covariance = second_moment_of_area_covariance_accumulator / area - centroid.x() * centroid.y();
std::cout << tag << std::endl;
std::cout << "area: " << area << std::endl;
std::cout << "centroid: " << centroid.x() << " " << centroid.y() << " " << centroid.z() << std::endl;
std::cout << "variance: " << variance.x() << " " << variance.y() << std::endl;
std::cout << "covariance: " << covariance << std::endl;
}
};
@ -277,6 +282,7 @@ struct Island {
float sticking_area { }; // for support points present on this layer (or bed extrusions)
Vec3f sticking_centroid_accumulator = Vec3f::Zero();
Vec2f sticking_second_moment_of_area_accumulator = Vec2f::Zero();
float sticking_second_moment_of_area_covariance_accumulator { };
std::vector<ExtrusionLine> external_lines;
};
@ -535,11 +541,15 @@ std::tuple<LayerIslands, PixelGrid> reckon_islands(
Vec2f middle = Vec2f((line.a + line.b) / 2.0f);
island.sticking_centroid_accumulator += sticking_area * to_3d(middle, float(layer->slice_z));
island.sticking_second_moment_of_area_accumulator += sticking_area * middle.cwiseProduct(middle);
island.sticking_second_moment_of_area_covariance_accumulator += sticking_area * middle.x()
* middle.y();
} else if (layer_lines[lidx].support_point_generated) {
float sticking_area = line.len * flow_width;
island.sticking_area += sticking_area;
island.sticking_centroid_accumulator += sticking_area * to_3d(line.b, float(layer->slice_z));
island.sticking_second_moment_of_area_accumulator += sticking_area * line.b.cwiseProduct(line.b);
island.sticking_second_moment_of_area_covariance_accumulator += sticking_area * line.b.x()
* line.b.y();
}
}
}
@ -574,6 +584,8 @@ std::tuple<LayerIslands, PixelGrid> reckon_islands(
* current_layer_grid.pixel_area();
connection.second_moment_of_area_accumulator += current_coords.cwiseProduct(current_coords)
* current_layer_grid.pixel_area();
connection.second_moment_of_area_covariance_accumulator += current_coords.x() * current_coords.y()
* current_layer_grid.pixel_area();
}
}
}
@ -601,6 +613,7 @@ class ObjectPart {
float sticking_area { };
Vec3f sticking_centroid_accumulator = Vec3f::Zero();
Vec2f sticking_second_moment_of_area_accumulator = Vec2f::Zero();
float sticking_second_moment_of_area_covariance_accumulator { };
public:
ObjectPart() = default;
@ -611,6 +624,8 @@ public:
this->sticking_area = island.sticking_area;
this->sticking_centroid_accumulator = island.sticking_centroid_accumulator;
this->sticking_second_moment_of_area_accumulator = island.sticking_second_moment_of_area_accumulator;
this->sticking_second_moment_of_area_covariance_accumulator =
island.sticking_second_moment_of_area_covariance_accumulator;
}
void add(const ObjectPart &other) {
@ -619,6 +634,8 @@ public:
this->sticking_area += other.sticking_area;
this->sticking_centroid_accumulator += other.sticking_centroid_accumulator;
this->sticking_second_moment_of_area_accumulator += other.sticking_second_moment_of_area_accumulator;
this->sticking_second_moment_of_area_covariance_accumulator +=
other.sticking_second_moment_of_area_covariance_accumulator;
}
void add_support_point(const Vec3f &position, float sticking_area) {
@ -626,6 +643,51 @@ public:
this->sticking_centroid_accumulator += sticking_area * position;
this->sticking_second_moment_of_area_accumulator += sticking_area
* position.head<2>().cwiseProduct(position.head<2>());
this->sticking_second_moment_of_area_covariance_accumulator += sticking_area
* position.x() * position.y();
}
float compute_elastic_section_modulus(
const Vec2f &line_dir,
const Vec3f &centroid_accumulator,
const Vec2f &second_moment_of_area_accumulator,
const float &second_moment_of_area_covariance_accumulator,
const float &area) const {
assert(area > 0);
Vec3f centroid = centroid_accumulator / area;
Vec2f variance = (second_moment_of_area_accumulator / area
- centroid.head<2>().cwiseProduct(centroid.head<2>()));
float covariance = second_moment_of_area_covariance_accumulator / area - centroid.x() * centroid.y();
// Var(aX+bY)=a^2*Var(X)+b^2*Var(Y)+2*a*b*Cov(X,Y)
float directional_xy_variance = line_dir.x() * line_dir.x() * variance.x()
+ line_dir.y() * line_dir.y() * variance.y() +
2.0f * line_dir.x() * line_dir.y() * covariance;
#ifdef DETAILED_DEBUG_LOGS
BOOST_LOG_TRIVIAL(debug)
<< "centroid: " << centroid.x() << " " << centroid.y() << " " << centroid.z();
BOOST_LOG_TRIVIAL(debug)
<< "variance: " << variance.x() << " " << variance.y();
BOOST_LOG_TRIVIAL(debug)
<< "covariance: " << covariance;
BOOST_LOG_TRIVIAL(debug)
<< "directional_xy_variance: " << directional_xy_variance;
#endif
if (directional_xy_variance < EPSILON) {
return 0.0f;
}
float extreme_fiber_dist = sqrt(area * directional_xy_variance);
float elastic_section_modulus = area * directional_xy_variance / extreme_fiber_dist;
#ifdef DETAILED_DEBUG_LOGS
BOOST_LOG_TRIVIAL(debug)
<< "extreme_fiber_dist: " << extreme_fiber_dist;
BOOST_LOG_TRIVIAL(debug)
<< "elastic_section_modulus: " << elastic_section_modulus;
#endif
return elastic_section_modulus;
}
float is_stable_while_extruding(
@ -636,20 +698,6 @@ public:
Vec2f line_dir = (extruded_line.b - extruded_line.a).normalized();
auto compute_elastic_section_modulus = [&line_dir](
const Vec3f &centroid_accumulator, const Vec2f &second_moment_of_area_accumulator, const float &area) {
Vec3f centroid = centroid_accumulator / area;
Vec2f variance = (second_moment_of_area_accumulator / area
- centroid.head<2>().cwiseProduct(centroid.head<2>()));
variance = variance.cwiseProduct(line_dir.cwiseAbs());
float extreme_fiber_dist = variance.cwiseSqrt().norm();
if (extreme_fiber_dist < EPSILON) {
return 0.0f;
}
float elastic_section_modulus = area * (variance.x() + variance.y()) / extreme_fiber_dist;
return elastic_section_modulus;
};
const Vec3f &mass_centroid = this->volume_centroid_accumulator / this->volume;
float mass = this->volume * params.filament_density;
float weight = mass * params.gravity_constant;
@ -669,8 +717,12 @@ public:
return 1.0f;
Vec3f bed_centroid = this->sticking_centroid_accumulator / this->sticking_area;
float bed_yield_torque = compute_elastic_section_modulus(this->sticking_centroid_accumulator,
this->sticking_second_moment_of_area_accumulator, this->sticking_area)
float bed_yield_torque = compute_elastic_section_modulus(
line_dir,
this->sticking_centroid_accumulator,
this->sticking_second_moment_of_area_accumulator,
this->sticking_second_moment_of_area_covariance_accumulator,
this->sticking_area)
* params.bed_adhesion_yield_strength;
float bed_weight_arm = (bed_centroid.head<2>() - mass_centroid.head<2>()).norm();
@ -686,7 +738,8 @@ public:
float bed_total_torque = bed_movement_torque + bed_extruder_conflict_torque + bed_weight_torque
- bed_yield_torque;
#if 1
#ifdef DETAILED_DEBUG_LOGS
BOOST_LOG_TRIVIAL(debug)
<< "bed_centroid: " << bed_centroid.x() << " " << bed_centroid.y() << " " << bed_centroid.z();
BOOST_LOG_TRIVIAL(debug)
@ -717,8 +770,12 @@ public:
return 1.0f;
Vec3f conn_centroid = connection.centroid_accumulator / connection.area;
float conn_yield_torque = compute_elastic_section_modulus(connection.centroid_accumulator,
connection.second_moment_of_area_accumulator, connection.area) * params.material_yield_strength;
float conn_yield_torque = compute_elastic_section_modulus(
line_dir,
connection.centroid_accumulator,
connection.second_moment_of_area_accumulator,
connection.second_moment_of_area_covariance_accumulator,
connection.area) * params.material_yield_strength;
float conn_weight_arm = (conn_centroid.head<2>() - mass_centroid.head<2>()).norm();
float conn_weight_torque = conn_weight_arm * weight * (conn_centroid.z() / layer_z);
@ -734,7 +791,7 @@ public:
float conn_total_torque = conn_movement_torque + conn_extruder_conflict_torque + conn_weight_torque
- conn_yield_torque;
#if 1
#ifdef DETAILED_DEBUG_LOGS
BOOST_LOG_TRIVIAL(debug)
<< "bed_centroid: " << conn_centroid.x() << " " << conn_centroid.y() << " " << conn_centroid.z();
BOOST_LOG_TRIVIAL(debug)
@ -936,6 +993,8 @@ Issues check_global_stability(SupportGridFilter supports_presence_grid,
weakest_conn.centroid_accumulator += support_point * area;
weakest_conn.second_moment_of_area_accumulator += area
* support_point.head<2>().cwiseProduct(support_point.head<2>());
weakest_conn.second_moment_of_area_covariance_accumulator += area * support_point.x()
* support_point.y();
}
}
}