3d bbox iou

https://logicatcore.github.io/scratchpad/lidar/sensor-fusion/jupyter/2021/04/20/2D-Oriented-Bounding-Box.html

http://www.open3d.org/docs/latest/python_api/open3d.geometry.OrientedBoundingBox.html

open3d.geometry.OrientedBoundingBox — Open3D master (684d7cd) documentation

https://github.com/google-research-datasets/Objectron

GitHub - google-research-datasets/Objectron: Objectron is a dataset of short, object-centric video clips. In addition, the video

https://github.com/google-research-datasets/Objectron/blob/c06a65165a18396e1e00091981fd1652875c97b5/objectron/dataset/box.py

GitHub - google-research-datasets/Objectron: Objectron is a dataset of short, object-centric video clips. In addition, the video

# for 3d iou
# reorder the corners from open3d definition to objectron box
open3d2objectron = [0, 1, 2, 4, 7, 3, 8, 6, 5]

# return center + corners of oriented bounding box from a point cloud
def get_oriented_3d_bbox(point_cloud: np.ndarray) -> np.ndarray:
    """
    point_cloud: (N, 3) np.ndarray

    Return
    vertices: (9, 3); 1 center + 8 corners
    
    """
    o3d_points = o3d.utility.Vector3dVector(point_cloud)
    oriented_3d_bbox = o3d.geometry.OrientedBoundingBox.create_from_points(o3d_points)
    center = oriented_3d_bbox.get_center()  # (3,)
    corners = oriented_3d_bbox.get_box_points()  # (8, 3)

    vertices = np.concatenate([np.asarray(center)[None, :], np.asarray(corners)])
    # reorder
    vertices = vertices[open3d2objectron]

    return vertices


# return 3d bounding box iou of two meshes (pointclouds)
def calc_3d_iou(mesh_a: np.ndarray, mesh_b: np.ndarray):
    """"
    mesh_a: (N1, 3)
    mesh_b: (N2, 3)

    Return
    iou: scalar 0~1
    
    """

    bbox_points_a = get_oriented_3d_bbox(mesh_a)  # (9, 3) center + 8 corners
    bbox_points_b = get_oriented_3d_bbox(mesh_b)  # (9, 3) center + 8 corners

    objectron_box_a = Box(bbox_points_a) 
    objectron_box_b = Box(bbox_points_b)
    
    IoU_calculator = IoU(objectron_box_a, objectron_box_b)
    iou = IoU_calculator.iou()

    return iou