SFMdata.py

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"""
A structure-from-motion example with landmarks
 - The landmarks form a 10 meter cube
 - The robot rotates around the landmarks, always facing towards the cube
"""
 
# pylint: disable=invalid-name, E1101
 
from typing import List
 
import numpy as np
 
from gtsam import Point3, Pose3, Rot3
 
 
def createPoints() -> List[Point3]:
    # Create the set of ground-truth landmarks
    points = [
        Point3(10.0, 10.0, 10.0),
        Point3(-10.0, 10.0, 10.0),
        Point3(-10.0, -10.0, 10.0),
        Point3(10.0, -10.0, 10.0),
        Point3(10.0, 10.0, -10.0),
        Point3(-10.0, 10.0, -10.0),
        Point3(-10.0, -10.0, -10.0),
        Point3(10.0, -10.0, -10.0),
    ]
    return points
 
 
_M_PI_2 = np.pi / 2
_M_PI_4 = np.pi / 4
 
 
def createPoses(
    init: Pose3 = Pose3(Rot3.Ypr(_M_PI_2, 0, -_M_PI_2), Point3(30, 0, 0)),
    delta: Pose3 = Pose3(
        Rot3.Ypr(0, -_M_PI_4, 0),
        Point3(np.sin(_M_PI_4) * 30, 0, 30 * (1 - np.sin(_M_PI_4))),
    ),
    steps: int = 8,
) -> List[Pose3]:
    """
    Create a set of ground-truth poses
    Default values give a circular trajectory, radius 30 at pi/4 intervals,
    always facing the circle center
    """
    poses = [init]
    for _ in range(1, steps):
        poses.append(poses[-1].compose(delta))
    return poses
 
 
def posesOnCircle(num_cameras=8, R=30):
    """Create regularly spaced poses with specified radius and number of cameras."""
    theta = 2 * np.pi / num_cameras
 
    # Initial pose at angle 0, position (R, 0, 0), facing the center with Y-axis pointing down
    init_rotation = Rot3.Ypr(_M_PI_2, 0, -_M_PI_2)
    init_position = np.array([R, 0, 0])
    init = Pose3(init_rotation, init_position)
 
    # Delta rotation: rotate by -theta around Z-axis (counterclockwise movement)
    delta_rotation = Rot3.Ypr(0, -theta, 0)
 
    # Delta translation in world frame
    delta_translation_world = np.array([R * (np.cos(theta) - 1), R * np.sin(theta), 0])
 
    # Transform delta translation to local frame of the camera
    delta_translation_local = init.rotation().unrotate(delta_translation_world)
 
    # Define delta pose
    delta = Pose3(delta_rotation, delta_translation_local)
 
    # Generate poses
    return createPoses(init, delta, num_cameras)