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RS-Helios-1615 User Manual

5.2 Point Cloud Display

5.2.1 Coordinate Mapping

Since the data packet output by the LiDAR only provides the horizontal rotation angle and distance

parameters, in order to present a 3D point cloud image, the angle and distance information in polar

coordinates need to be converted into x, y, z coordinates in the Cartesian coordinate system, and

the conversion formula is as follows:

{

𝑥=𝑟𝑐𝑜𝑠(𝜔)𝑠𝑖𝑛(𝛼);

𝑦=𝑟𝑐𝑜𝑠(𝜔)𝑐𝑜𝑠(𝛼);

𝑧=𝑟𝑠𝑖𝑛(𝜔);

Where 𝑟 is the measured distance, is the vertical angle of the laser, is the horizontal

rotation angle of the laser in the Polar Coordinate System, and x, y, z are the coordinate values in

the Cartesian Coordinate System.

Note 1: ROS source code of RS-Helios-1615 has by default completed the coordinate conversion to conform to the

right-handed coordinate system of ROS. The X-axis of ROS is the positive Y direction in Figure 1, and the Y-axis of

ROS is the negative X direction in Figure 1.

Note 2: The origin of the LiDAR sensor coordinate is 63.5mm above the LiDAR base, on the center axis.

5.3 Reflectivity

RS-Helios-1615 measures the reflectivity of objects. The reflectivity is an index that measures the

ability of an object to reflect light and is greatly related to the material of the object itself. Therefore,

the reflectivity information can be used to distinguish objects of different materials.

RS-Helios-1615 reports calibrated reflectivity values from 0 to 255, among which diffuse reflectors

report values from 0 to 100, and retroreflectors report values from 101 to 255. Black objects are

with low reflectivity values, white objects are with high reflectivity values, the most ideal reflection

reports the reflectivity value of 255.

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RoboSense LIDAR RS-Helios-1615 User Manual

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