LIDAR point to laser ring number association

rfsch · August 14, 2019, 6:33am

Hi

I think it would be useful to have the association of the point to the laser number (layer/32 individ. lasers).

Do you think it is possible that you will have it in the future

Khaled_Elmadawi · July 1, 2019, 6:38pm

Hi,
I am facing the same problem, I translated \ rotated the point cloud to it’s original FOR, but no clue why it is not giving me the spherical angles that may be used as IDX for ring layers

holger-motional · July 3, 2019, 6:53am

Take a look at this:

github.com

nutonomy/nuscenes-devkit/blob/master/python-sdk/nuscenes/utils/data_classes.py#L249


def nbr_dims() -> int:
    """
    Returns the number of dimensions.
    :return: Number of dimensions.
    """
    return 4


@classmethod
def from_file(cls, file_name: str) -> 'LidarPointCloud':
    """
    Loads LIDAR data from binary numpy format. Data is stored as (x, y, z, intensity, ring index).
    :param file_name: Path of the pointcloud file on disk.
    :return: LidarPointCloud instance (x, y, z, intensity).
    """


    assert file_name.endswith('.bin'), 'Unsupported filetype {}'.format(file_name)


    scan = np.fromfile(file_name, dtype=np.float32)
    points = scan.reshape((-1, 5))[:, :cls.nbr_dims()]
    return cls(points.T)

We have the ring index, but drop it by default.

Khaled_Elmadawi · July 3, 2019, 7:58am

Thanks Holger, but don’t you have any missing points(dis=0,intensity=0), in other words an attenuated signal?

holger-motional · July 15, 2019, 6:15am

Unfortunately we do. So in that case you may have to use some heuristics to retrieve it.

Khaled_Elmadawi · July 16, 2019, 10:30am

can you illustrate more please?, what do you do?

holger-motional · August 10, 2019, 3:54am

Sorry, I didn’t get a message upon your response.
By “we do” I mean that there are missing points which are discarded as they are not in a reasonable range (not sure how the driver internally works).