Vignesh_93's profile - activity

Hello ROS developers, I am trying to convert a2D array to a point cloud value and publish it thereby visualising it in rviz. Can anyone guide me to solve the below issue which I am facing during the conversion ? This is the code and I get the error stated below that.

def scanProcessing(msg):
    laserProj = LaserProjection()
    cloud_out = laserProj.projectLaser(msg)
    xyz_array = ros_numpy.point_cloud2.pointcloud2_to_xyz_array(cloud_out)
    stamp = rospy.Time.now()
    frame_id = 'odom'
    xyz_coordinate = [[x[i],y[i], z[i]] for i in range(len(x))]
    print(xyz_array)
    header = std_msgs.msg.Header()
    header.stamp = rospy.Time.now()
    header.frame_id = 'map'
    cloud_msg = ros_numpy.point_cloud2.array_to_pointcloud2(xyz_array, stamp, frame_id)
    pointcloud_publisher.publish(cloud_msg)

if __name__ == "__main__":
    rospy.init_node('scan_processor')
    pointcloud_publisher = rospy.Publisher("/my_pointcloud_topic", PointCloud, queue_size=1)
    scanSubscriber = rospy.Subscriber('/robot2/scan', LaserScan, scanProcessing, queue_size=1)        
    rospy.spin()

The Error observed is:

[ERROR] [1614671648.584787, 6.342000]: bad callback: <function scanProcessing at 0x7f88928728b0>
Traceback (most recent call last):
  File "/opt/ros/noetic/lib/python3/dist-packages/rospy/topics.py", line 750, in _invoke_callback
    cb(msg)
  File "pointCloud_v8.py", line 120, in scanProcessing
    cloud_msg = ros_numpy.point_cloud2.array_to_pointcloud2(xyz_array, stamp, frame_id)
  File "/opt/ros/noetic/lib/python3/dist-packages/ros_numpy/point_cloud2.py", line 147, in array_to_pointcloud2
    cloud_msg.fields = dtype_to_fields(cloud_arr.dtype)
  File "/opt/ros/noetic/lib/python3/dist-packages/ros_numpy/point_cloud2.py", line 92, in dtype_to_fields
    for field_name in dtype.names:
TypeError: 'NoneType' object is not iterable

P.S: As I understand this is a bit basic question. I would really appreciate some answers which could help me to continue my ROS journey

Edit 1: To emphasize more on the issue side from the comments :

Inside the function array_to_pointcloud2 there is a conversion to a 2D array. After which an object of pointCloud2 is created and the field attribute is associated with the data type of the array which in my case is 'float64' So basically dtype = 'foat64' All all good till the below function, iteration over dtype.names takes place which is None (which is logical), is there anything which we must do to tag it along with the dtype ?

 def dtype_to_fields(dtype):
         fields = []
         for field_name in dtype.names:
             np_field_type, field_offset = dtype.fields[field_name]
             pf = PointField()
             pf.name = field_name
             if np_field_type.subdtype:
                 item_dtype, shape = np_field_type.subdtype
                 pf.count = np.prod(shape)
                 np_field_type = item_dtype
             else:
                 pf.count = 1 ...(more code)...

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