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RS-Ruby Lite Users’ Manual
19
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
coordinates in Cartesian Coordinate System, as shown in Figure 11. The function of how to
transfer the information is as shown below:
� ⺄ 굠ᢄ ᢄth
� ⺄ 굠ᢄ 굠ᢄ
� ⺄ ᢄth
Here
⺄
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 can be exported per RSView in angle.csv and defined in Table 7.
Figure 11: Coordinate system mapping between polar system and XYZ system.
Note 1: In the RS-Ruby Lite 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 11.
The ROS-Y axis is co-axis with the X-axis but the positive direction is reverse as Figure 11.
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
.