Add LiDAR RTK hand-eye calibration workflow and results

code/visualize_pair_3d.py

@@ -0,0 +1,169 @@
+#!/usr/bin/env python3
+"""Interactive 3D comparison of raw, RTK, GICP and hand-eye-predicted motion."""
+import argparse
+import json
+
+import numpy as np
+from scipy.spatial.transform import Rotation
+
+from rigorous_calibration import (
+    inverse_transform, load_stations, rotation_angle_deg, rpy_deg, transform_points,
+)
+
+
+COLORS = {
+    "target": [0.10, 0.65, 1.00],
+    "source": [1.00, 0.35, 0.05],
+}
+
+
+def cloud(o3d, points, color, voxel):
+    item = o3d.geometry.PointCloud()
+    item.points = o3d.utility.Vector3dVector(points)
+    item = item.voxel_down_sample(voxel)
+    item.paint_uniform_color(color)
+    return item
+
+
+def delta_components(reference, candidate):
+    """Components of reference^-1*candidate, plus coordinate-invariant norms."""
+    delta = inverse_transform(reference) @ candidate
+    translation = np.asarray(delta[:3, 3], float)
+    return {
+        "translation_xyz_cm": (translation * 100.0).tolist(),
+        "translation_norm_cm": float(np.linalg.norm(translation) * 100.0),
+        "rotation_rpy_deg_xyz": rpy_deg(delta[:3, :3]),
+        "rotation_angle_deg": rotation_angle_deg(delta[:3, :3]),
+    }
+
+
+def body_left_rpy(x, rpy_correction_deg):
+    correction = np.eye(4)
+    correction[:3, :3] = Rotation.from_euler(
+        "xyz", np.asarray(rpy_correction_deg, float), degrees=True
+    ).as_matrix()
+    return correction @ x
+
+
+def print_delta(name, reference, candidate):
+    item = delta_components(reference, candidate)
+    tx, ty, tz = item["translation_xyz_cm"]
+    roll, pitch, yaw = item["rotation_rpy_deg_xyz"]
+    print(
+        f"{name}: B^-1*motion translation xyz = "
+        f"[{tx:+.4f}, {ty:+.4f}, {tz:+.4f}] cm; "
+        f"rpy xyz = [{roll:+.4f}, {pitch:+.4f}, {yaw:+.4f}] deg; "
+        f"norm = {item['translation_norm_cm']:.4f} cm / "
+        f"{item['rotation_angle_deg']:.6f} deg"
+    )
+    return item
+
+
+def main():
+    import open3d as o3d
+
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--frames", required=True)
+    parser.add_argument("--pairs", required=True)
+    parser.add_argument("--extrinsic", required=True)
+    parser.add_argument("--pair-index", type=int, default=0)
+    parser.add_argument("--voxel", type=float, default=0.10)
+    parser.add_argument(
+        "--left-rpy-deg", nargs=3, type=float, default=[0.0, 0.0, 0.0],
+        metavar=("ROLL", "PITCH", "YAW"),
+        help="optional body-frame left correction applied as DeltaR_body * X",
+    )
+    args = parser.parse_args()
+
+    stations = load_stations(args.frames, 1.0, 60.0)
+    with np.load(args.pairs, allow_pickle=False) as data:
+        if len(stations) != len(data["station_times"]):
+            raise ValueError(
+                f"frames contain {len(stations)} stations but pair file records "
+                f"{len(data['station_times'])}"
+            )
+        if not 0 <= args.pair_index < len(data["A"]):
+            raise IndexError(
+                f"pair-index {args.pair_index} outside [0,{len(data['A']) - 1}]"
+            )
+        a_ij = np.asarray(data["A"][args.pair_index], float)
+        b_gicp = np.asarray(data["B"][args.pair_index], float)
+        i, j = np.asarray(data["meta"][args.pair_index, :2], int)
+
+    with open(args.extrinsic, encoding="utf-8-sig") as stream:
+        result = json.load(stream)
+    x = np.asarray(result["matrix_4x4"], float)
+    b_calibrated = inverse_transform(x) @ a_ij @ x
+
+    transforms = {
+        "1 raw": np.eye(4),
+        "2 RTK initial (X0=I)": a_ij,
+        "3 GICP B": b_gicp,
+        "4 calibrated X^-1 A X": b_calibrated,
+    }
+    correction = np.asarray(args.left_rpy_deg, float)
+    if np.any(np.abs(correction) > 0.0):
+        x_test = body_left_rpy(x, correction)
+        transforms[
+            f"5 test body-left RPY {correction.tolist()} deg"
+        ] = inverse_transform(x_test) @ a_ij @ x_test
+
+    target = stations[i][3]
+    source = stations[j][3]
+    print(f"pair_index={args.pair_index}, station {i} <- {j}")
+    print("blue = target station i; orange = source station j after selected transform")
+    print("keys: 1 raw | 2 RTK initial | 3 GICP | 4 calibrated | 5 test correction | Q/Esc exit")
+    print(
+        "IMPORTANT: delta xyz/rpy are components of B^-1*(X^-1*A*X), expressed "
+        "in station-j LiDAR coordinates; screen-left/right depends on the 3D camera view."
+    )
+    baseline = print_delta("mode 4 minus mode 3", b_gicp, b_calibrated)
+    roll, pitch, yaw = np.abs(baseline["rotation_rpy_deg_xyz"])
+    if max(roll, pitch) > max(0.10, 2.0 * yaw):
+        print("diagnosis: roll/pitch components dominate yaw; do not prioritize yaw tuning for this pair.")
+    tx, ty, tz = np.abs(baseline["translation_xyz_cm"])
+    if tz > max(tx, ty):
+        print("diagnosis: the largest translation component is relative Z, not lateral XY.")
+    body_up = np.array([0.0, 0.0, 1.0])
+    if np.linalg.norm(a_ij[:3, :3] @ body_up - body_up) < 1e-8:
+        print(
+            "observability: this A preserves the body Z axis, so body-left X.z "
+            "translation is unobservable from this pair; use ground/external height constraints."
+        )
+    if "5 test body-left RPY " + str(correction.tolist()) + " deg" in transforms:
+        print_delta("mode 5 minus mode 3", b_gicp, list(transforms.values())[-1])
+
+    viewer = o3d.visualization.VisualizerWithKeyCallback()
+    viewer.create_window("Rigorous LiDAR registration inspection - 3D", 1400, 900)
+    target_cloud = cloud(o3d, target, COLORS["target"], args.voxel)
+    source_cloud = cloud(o3d, source, COLORS["source"], args.voxel)
+    viewer.add_geometry(target_cloud)
+    viewer.add_geometry(source_cloud)
+    axes = o3d.geometry.TriangleMesh.create_coordinate_frame(size=1.0)
+    viewer.add_geometry(axes)
+    current = np.eye(4)
+
+    def select(name):
+        def callback(vis):
+            nonlocal current
+            desired = transforms[name]
+            source_cloud.transform(desired @ inverse_transform(current))
+            current = desired
+            vis.update_geometry(source_cloud)
+            if name == "3 GICP B":
+                print(f"{name}: reference registration B; delta = 0")
+            else:
+                print_delta(name + " minus mode 3", b_gicp, desired)
+            return False
+        return callback
+
+    for key, name in zip((ord("1"), ord("2"), ord("3"), ord("4"), ord("5")), transforms):
+        viewer.register_key_callback(key, select(name))
+    viewer.get_render_option().background_color = np.array([0.02, 0.02, 0.02])
+    viewer.get_render_option().point_size = 2.0
+    viewer.run()
+    viewer.destroy_window()
+
+
+if __name__ == "__main__":
+    main()