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RS-Ruby Users’ Manual
14
8 Point Cloud
8.1 Coordinating Mapping
In data packet including the measured azimuth and distance, in order to calculating the
point cloud, the coordinate in polar coordinate system should be transferred to the 3D
XYZ coordinate in Cartesian Coordinate System, as shown in figure 8. The function of
how to transfer the information is as shown below:
t h th h঩
t h th th
t h h঩
Here
h
is the reported distance,

is the vertical angle/elevation of the laser (which is
fixed and is given by the Laser ID), and

is the horizontal angle/azimuth reported at the
beginning of every other firing sequence.

is the angle offset of the azimuth. x, y, z
values are the projection of the polar coordinates on the XYZ Cartesian Coordinate
System.
The value of
ω
and defined in Table 7.
Figure 8. Coordinate system mapping between polar system and XYZ system.
Note 1: In the RS-Ruby ROS package, the coordinate system must be transferred to the ROS
right-hand Coordinate system.
The ROS-X axis is co-axis with the Y-axis and with same direction as Figure 8.
The ROS-Y axis is co-axis with the X-axis but the positive direction is reverse as Figure 8.
The Z axis is same before and after transformation.
Note 2: The origin of the LiDAR coordinate is defined at the center of the LiDAR structure, with
68 mm high to the bottom of the LiDAR
.