Creating 3D Bounding Boxes

obraun-sl · January 8, 2021, 7:28am

There is no ready-to-use sample that convert 2D to 3D boxes but you can take a look at the repository here :

You can use this function here :

stereolabs/zed-yolo/blob/master/zed_python_sample/darknet_zed.py#L264


    res = sorted(res, key=lambda x: -x[1])
    free_detections(dets, num)
    return res
netMain = None
metaMain = None
altNames = None
def get_object_depth(depth, bounds):
    '''
    Calculates the median x, y, z position of top slice(area_div) of point cloud
    in camera frame.
    Arguments:
        depth: Point cloud data of whole frame.
        bounds: Bounding box for object in pixels.
            bounds[0]: x-center
            bounds[1]: y-center
            bounds[2]: width of bounding box.
            bounds[3]: height of bounding box.

Instead of using the center of the bbox 2D (bounds[0] /bounds[1]), use the 4 points of the 2D bbox and convert to 3D using the same code. it will return a X,Y,Z for each 4 points.

To create the 4 remaining points, you need to generate them using an arbitrary rule that might depend on the object class:
A simple way would be to say that the 4 remaining points are 1m away in the Z axis from the existing 4 3D points.
It could be 1m away on the Z axis or 1m away on the camera -> object axis. This 1 meter value will fit for people but you might change for other objects.