def view_points()

in metropolis/utils/geometry_utils.py [0:0]

• 13 lines of code
• 2 McCabe index (conditional complexity)

def view_points(points: np.ndarray, view: np.ndarray, normalize: bool) -> np.ndarray:
    """
    This is a helper class that maps 3d points to a 2d plane. It can be used to implement both perspective and
    orthographic projections. It first applies the dot product between the points and the view. By convention,
    the view should be such that the data is projected onto the first 2 axis. It then optionally applies a
    normalization along the third dimension.

    For a perspective projection the view should be a 3x3 camera matrix, and normalize=True
    For an orthographic projection with translation the view is a 3x4 matrix and normalize=False
    For an orthographic projection without translation the view is a 3x3 matrix (optionally 3x4 with last columns
     all zeros) and normalize=False

    Args:
        points: Matrix of points, where each point (x, y, z) is along each column.
        view: Defines an arbitrary projection (n <= 4). The projection should be
            such that the corners are projected onto the first 2 axis.
        normalize: Whether to normalize the remaining coordinate (along the third axis).

    Returns:
        Mapped point. If normalize=False, the third coordinate is the height.
    """

    assert view.shape[0] <= 4
    assert view.shape[1] <= 4
    assert points.shape[0] == 3

    viewpad = np.eye(4)
    viewpad[: view.shape[0], : view.shape[1]] = view

    nbr_points = points.shape[1]

    # Do operation in homogenous coordinates.
    points = np.concatenate((points, np.ones((1, nbr_points))))
    points = np.dot(viewpad, points)
    points = points[:3, :]

    if normalize:
        points = points / points[2:3, :].repeat(3, 0).reshape(3, nbr_points)

    return points