new: camera pose from spherical coordinate system

[yxlao]

Features

New: Convert spherical coordinates to camera extrinsic

ct.convert.spherical_to_T_towards_origin(radius, theta, phi)

The converted camera extrinsic has the following properties:

• The camera is centered at the point specified by the spherical coordinates.
• The camera points to the origin.
• The camera's "up" direction aligns with the +Z axis (meaning, the angle is <= pi/2).

The spherical coordinates are defined using the ISO standard (Ref).

New: Convert Euler coordinates to rotation matrix

ct.convert.euler_to_R(yaw, pitch, roll)

Example

import camtools as ct
import numpy as np
import open3d as o3d
import itertools


def main():
    K = np.array(
        [
            [554.256, 0.0, 320],
            [0.0, 554.256, 240],
            [0.0, 0.0, 1.0],
        ]
    )

    resolution = 12
    radius = 1.0
    thetas = np.linspace(0, np.pi, resolution, endpoint=False)[1:]
    phis = np.linspace(0, 2 * np.pi, resolution, endpoint=False)

    Ts = [
        ct.convert.spherical_to_T_towards_origin(radius, theta, phi)
        for (theta, phi) in itertools.product(thetas, phis)
    ]
    Ks = [K for _ in range(len(Ts))]

    # Old API is ct.camera.create_camera_ray_frames
    cameras = ct.camera.create_camera_frames(Ks=Ks, Ts=Ts, center_line=False)
    axes = o3d.geometry.TriangleMesh.create_coordinate_frame(size=1.0)
    o3d.visualization.draw_geometries([cameras, axes])


if __name__ == "__main__":
    main()

Some notes on creating gif:

# Speed up and then use Handbrake to generate MP4
mencoder -speed 2 -o sphere_camera_fast.webm -ovc copy sphere_camera.webm

# Convert webm to gif
wget https://github.com/ImageOptim/gifski/releases/download/1.11.0/gifski_1.11.0_amd64.deb
sudo dpkg -i gifski_1.11.0_amd64.deb
gifski sphere_camera_fast.webm -o sphere_camera.gif -r 12 --fast-forward 2 -Q 90 -H 480 --extra --repeat 0