Move geometry lib to frc971/vision
Going to use for target mapping. Previously used this for 2022 vision.
Signed-off-by: Milind Upadhyay <milind.upadhyay@gmail.com>
Change-Id: Ifd9d13d3f9b0ea1aac42fb6c96ef2a5062b9f637
diff --git a/frc971/vision/BUILD b/frc971/vision/BUILD
index ca35f7c..65d236d 100644
--- a/frc971/vision/BUILD
+++ b/frc971/vision/BUILD
@@ -86,3 +86,28 @@
"@org_tuxfamily_eigen//:eigen",
],
)
+
+cc_library(
+ name = "geometry_lib",
+ hdrs = [
+ "geometry.h",
+ ],
+ target_compatible_with = ["@platforms//os:linux"],
+ visibility = ["//visibility:public"],
+ deps = [
+ "//aos/util:math",
+ "//third_party:opencv",
+ "@com_github_google_glog//:glog",
+ ],
+)
+
+cc_test(
+ name = "geometry_test",
+ srcs = [
+ "geometry_test.cc",
+ ],
+ deps = [
+ ":geometry_lib",
+ "//aos/testing:googletest",
+ ],
+)
diff --git a/frc971/vision/geometry.h b/frc971/vision/geometry.h
new file mode 100644
index 0000000..e3527f5
--- /dev/null
+++ b/frc971/vision/geometry.h
@@ -0,0 +1,136 @@
+#ifndef FRC971_VISION_GEOMETRY_H_
+#define FRC971_VISION_GEOMETRY_H_
+
+#include "aos/util/math.h"
+#include "glog/logging.h"
+#include "opencv2/core/types.hpp"
+
+namespace frc971::vision {
+
+// Linear equation in the form y = mx + b
+struct SlopeInterceptLine {
+ double m, b;
+
+ inline SlopeInterceptLine(cv::Point2d p, cv::Point2d q) {
+ if (p.x == q.x) {
+ CHECK_EQ(p.y, q.y) << "Can't fit line to infinite slope";
+
+ // If two identical points were passed in, give the slope 0,
+ // with it passing the point.
+ m = 0.0;
+ } else {
+ m = (p.y - q.y) / (p.x - q.x);
+ }
+ // y = mx + b -> b = y - mx
+ b = p.y - (m * p.x);
+ }
+
+ inline double operator()(double x) const { return (m * x) + b; }
+};
+
+// Linear equation in the form ax + by = c
+struct StdFormLine {
+ public:
+ double a, b, c;
+
+ inline std::optional<cv::Point2d> Intersection(const StdFormLine &l) const {
+ // Use Cramer's rule to solve for the intersection
+ const double denominator = Determinant(a, b, l.a, l.b);
+ const double numerator_x = Determinant(c, b, l.c, l.b);
+ const double numerator_y = Determinant(a, c, l.a, l.c);
+
+ std::optional<cv::Point2d> intersection = std::nullopt;
+ // Return nullopt if the denominator is 0, meaning the same slopes
+ if (denominator != 0) {
+ intersection =
+ cv::Point2d(numerator_x / denominator, numerator_y / denominator);
+ }
+
+ return intersection;
+ }
+
+ private: // Determinant of [[a, b], [c, d]]
+ static inline double Determinant(double a, double b, double c, double d) {
+ return (a * d) - (b * c);
+ }
+};
+
+struct Circle {
+ public:
+ cv::Point2d center;
+ double radius;
+
+ static inline std::optional<Circle> Fit(std::vector<cv::Point2d> points) {
+ CHECK_EQ(points.size(), 3ul);
+ // For the 3 points, we have 3 equations in the form
+ // (x - h)^2 + (y - k)^2 = r^2
+ // Manipulate them to solve for the center and radius
+ // (x1 - h)^2 + (y1 - k)^2 = r^2 ->
+ // x1^2 + h^2 - 2x1h + y1^2 + k^2 - 2y1k = r^2
+ // Also, (x2 - h)^2 + (y2 - k)^2 = r^2
+ // Subtracting these two, we get
+ // x1^2 - x2^2 - 2h(x1 - x2) + y1^2 - y2^2 - 2k(y1 - y2) = 0 ->
+ // h(x1 - x2) + k(y1 - y2) = (-x1^2 + x2^2 - y1^2 + y2^2) / -2
+ // Doing the same with equations 1 and 3, we get the second linear equation
+ // h(x1 - x3) + k(y1 - y3) = (-x1^2 + x3^2 - y1^2 + y3^2) / -2
+ // Now, we can solve for their intersection and find the center
+ const auto l =
+ StdFormLine{points[0].x - points[1].x, points[0].y - points[1].y,
+ (-std::pow(points[0].x, 2) + std::pow(points[1].x, 2) -
+ std::pow(points[0].y, 2) + std::pow(points[1].y, 2)) /
+ -2.0};
+ const auto m =
+ StdFormLine{points[0].x - points[2].x, points[0].y - points[2].y,
+ (-std::pow(points[0].x, 2) + std::pow(points[2].x, 2) -
+ std::pow(points[0].y, 2) + std::pow(points[2].y, 2)) /
+ -2.0};
+ const auto center = l.Intersection(m);
+
+ std::optional<Circle> circle = std::nullopt;
+ if (center) {
+ // Now find the radius
+ const double radius = cv::norm(points[0] - *center);
+ circle = Circle{*center, radius};
+ }
+ return circle;
+ }
+
+ inline double DistanceTo(cv::Point2d p) const {
+ const auto p_prime = TranslateToOrigin(p);
+ // Now, the distance is simply the difference between distance from the
+ // origin to p' and the radius.
+ return std::abs(cv::norm(p_prime) - radius);
+ }
+
+ inline double AngleOf(cv::Point2d p) const {
+ auto p_prime = TranslateToOrigin(p);
+ // Flip the y because y values go downwards.
+ p_prime.y *= -1;
+ return std::atan2(p_prime.y, p_prime.x);
+ }
+
+ // Expects all angles to be from 0 to 2pi
+ // TODO(milind): handle wrapping
+ static inline bool AngleInRange(double theta, double theta_min,
+ double theta_max) {
+ return (
+ (theta >= theta_min && theta <= theta_max) ||
+ (theta_min > theta_max && (theta >= theta_min || theta <= theta_max)));
+ }
+
+ inline bool InAngleRange(cv::Point2d p, double theta_min,
+ double theta_max) const {
+ return AngleInRange(AngleOf(p), theta_min, theta_max);
+ }
+
+ private:
+ // Translate the point on the circle
+ // as if the circle's center is the origin (0,0)
+ inline cv::Point2d TranslateToOrigin(cv::Point2d p) const {
+ return cv::Point2d(p.x - center.x, p.y - center.y);
+ }
+};
+
+} // namespace frc971::vision
+
+#endif // FRC971_VISION_GEOMETRY_H_
diff --git a/frc971/vision/geometry_test.cc b/frc971/vision/geometry_test.cc
new file mode 100644
index 0000000..19e54c4
--- /dev/null
+++ b/frc971/vision/geometry_test.cc
@@ -0,0 +1,111 @@
+#include "frc971/vision/geometry.h"
+
+#include <cmath>
+
+#include "aos/util/math.h"
+#include "glog/logging.h"
+#include "gtest/gtest.h"
+
+namespace frc971::vision::testing {
+
+TEST(GeometryTest, SlopeInterceptLine) {
+ // Test a normal line
+ {
+ SlopeInterceptLine l({2.0, 3.0}, {4.0, 2.0});
+ EXPECT_DOUBLE_EQ(l.m, -0.5);
+ EXPECT_DOUBLE_EQ(l.b, 4.0);
+ EXPECT_DOUBLE_EQ(l(5), 1.5);
+ }
+ // Test a horizontal line
+ {
+ SlopeInterceptLine l({2.0, 3.0}, {4.0, 3.0});
+ EXPECT_DOUBLE_EQ(l.m, 0.0);
+ EXPECT_DOUBLE_EQ(l.b, 3.0);
+ EXPECT_DOUBLE_EQ(l(1000.0), 3.0);
+ }
+ // Test duplicate points
+ {
+ SlopeInterceptLine l({2.0, 3.0}, {2.0, 3.0});
+ EXPECT_DOUBLE_EQ(l.m, 0.0);
+ EXPECT_DOUBLE_EQ(l.b, 3.0);
+ EXPECT_DOUBLE_EQ(l(1000.0), 3.0);
+ }
+ // Test infinite slope
+ {
+ EXPECT_DEATH(SlopeInterceptLine({2.0, 3.0}, {2.0, 5.0}),
+ "(.*)infinite slope(.*)");
+ }
+}
+
+TEST(GeometryTest, StdFormLine) {
+ // Test the intersection of normal lines
+ {
+ StdFormLine l{3.0, 2.0, 2.3};
+ StdFormLine m{-2.0, 1.2, -0.3};
+ const cv::Point2d kIntersection = {42.0 / 95.0, 37.0 / 76.0};
+ EXPECT_EQ(*l.Intersection(m), kIntersection);
+ EXPECT_EQ(*m.Intersection(l), kIntersection);
+ }
+ // Test the intersection of parallel lines
+ {
+ StdFormLine l{-3.0, 2.0, -3.7};
+ StdFormLine m{-6.0, 4.0, 0.1};
+ EXPECT_EQ(l.Intersection(m), std::nullopt);
+ EXPECT_EQ(m.Intersection(l), std::nullopt);
+ }
+ // Test the intersection of duplicate lines
+ {
+ StdFormLine l{6.0, -8.0, 0.23};
+ StdFormLine m{6.0, -8.0, 0.23};
+ EXPECT_EQ(l.Intersection(m), std::nullopt);
+ EXPECT_EQ(m.Intersection(l), std::nullopt);
+ }
+}
+
+TEST(GeometryTest, Circle) {
+ // Test fitting a normal circle
+ {
+ auto c = Circle::Fit({{-6.0, 3.2}, {-3.0, 2.0}, {-9.3, 1.4}});
+ EXPECT_TRUE(c.has_value());
+ EXPECT_NEAR(c->center.x, -5.901, 1e-3);
+ EXPECT_NEAR(c->center.y, -0.905, 1e-3);
+ EXPECT_NEAR(c->radius, 4.106, 1e-3);
+
+ // Coordinate systems flipped because of image
+ const cv::Point2d kPoint = {c->center.x - c->radius * std::sqrt(3.0) / 2.0,
+ c->center.y - c->radius / 2.0};
+ EXPECT_NEAR(c->AngleOf(kPoint), 5.0 * M_PI / 6.0, 1e-5);
+ EXPECT_TRUE(c->InAngleRange(kPoint, 4.0 * M_PI / 6.0, M_PI));
+ EXPECT_FALSE(c->InAngleRange(kPoint, 0, 2.0 * M_PI / 6.0));
+ EXPECT_EQ(c->DistanceTo(kPoint), 0.0);
+
+ const cv::Point2d kZeroPoint = {c->center.x + c->radius, c->center.y};
+ EXPECT_NEAR(c->AngleOf(kZeroPoint), 0.0, 1e-5);
+ EXPECT_TRUE(c->InAngleRange(kZeroPoint, (2.0 * M_PI) - 0.1, 0.1));
+ EXPECT_EQ(c->DistanceTo(kZeroPoint), 0.0);
+
+ // Test the distance to another point
+ const cv::Point2d kDoubleDistPoint = {
+ c->center.x - (c->radius * 2.0) * std::sqrt(3.0) / 2.0,
+ c->center.y - (c->radius * 2.0) / 2.0};
+ EXPECT_DOUBLE_EQ(c->DistanceTo(kDoubleDistPoint), c->radius);
+
+ // Distance to center should be radius
+ EXPECT_DOUBLE_EQ(c->DistanceTo(c->center), c->radius);
+ }
+ // Test fitting an invalid circle (duplicate points)
+ {
+ auto c = Circle::Fit({{-6.0, 3.2}, {-3.0, 2.0}, {-6.0, 3.2}});
+ EXPECT_FALSE(c.has_value());
+ }
+ // Test if angles are in ranges
+ {
+ EXPECT_TRUE(Circle::AngleInRange(0.5, 0.4, 0.6));
+ EXPECT_TRUE(Circle::AngleInRange(0, (2.0 * M_PI) - 0.2, 0.2));
+ EXPECT_FALSE(
+ Circle::AngleInRange(0, (2.0 * M_PI) - 0.2, (2.0 * M_PI) - 0.1));
+ EXPECT_TRUE(Circle::AngleInRange(0.5, (2.0 * M_PI) - 0.1, 0.6));
+ }
+}
+
+} // namespace frc971::vision::testing