Function get_new_camera_matrix

data_toolkit/utils.py:453–493

Compute camera-to-world 4x4 transform matrix in spherical coordinates, looking at origin with up=(0,1,0). Uses standard LookAt formula where camera local -Z points at target and local Y is up. An additional +90 degree rotation around local Z axis is applied to match Blender Trac

(radius: float, yaw: float, pitch: float, dtype=torch.float32, device='cpu')

import math

def get_new_camera_matrix(radius: float, yaw: float, pitch: float, dtype=torch.float32, device='cpu'):
    """
    Compute camera-to-world 4x4 transform matrix in spherical coordinates,
    looking at origin with up=(0,1,0).
    Uses standard LookAt formula where camera local -Z points at target and local Y is up.
    An additional +90 degree rotation around local Z axis is applied to match
    Blender Track-To local axis convention.
    yaw, pitch are in radians.
    """
    x = radius * math.cos(yaw) * math.cos(pitch)
    y = radius * math.sin(yaw) * math.cos(pitch)
    z = radius * math.sin(pitch)
    eye = torch.tensor([x, y, z], dtype=dtype, device=device)
    target = torch.zeros(3, dtype=dtype, device=device)
    up_global = torch.tensor([0.0, 1.0, 0.0], dtype=dtype, device=device)

    f = (target - eye)
    f = f / torch.norm(f)
    r = torch.cross(f, up_global)
    r = r / torch.norm(r)
    u = torch.cross(r, f)

    z_cam = -f
    x_cam = r
    y_cam = u

    T = torch.eye(4, dtype=dtype, device=device)
    T[:3, 0] = x_cam
    T[:3, 1] = y_cam
    T[:3, 2] = z_cam
    T[:3, 3] = eye

    # +90 degree rotation matrix around local Z axis
    Rz90 = torch.tensor([
        [0.0, -1.0, 0.0, 0.0],
        [1.0,  0.0, 0.0, 0.0],
        [0.0,  0.0, 1.0, 0.0],
        [0.0,  0.0, 0.0, 1.0]
    ], dtype=dtype, device=device)

    return T @ Rz90


def transform_mesh(mesh_v, frame):