LSLIDAR CH128X1 - 7.3 Distance Value and Intensity; 7.4 Cartesian Coordinate Representation

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Endian mode. The unit is 0.01 degrees. For example, 0x11AD=4525, that is
45.25°.
7.3 Distance Value and Intensity
Byte 4, Byte 5, and Byte 6 represent the the first echo distance value. Their data
are stored in Big-Endian mode. The two high bytes are the integer part, whose
unit is “cm”; and the last byte is the decimal part, whose unit is 1/256 cm. To
analyze the distance value, for example: the distance value in the obtained data
packet is represented by the hexadecimal number 0x02, 0x18, 0x32, and the
first two bytes are composed of 16-bit unsigned data, that is: 0x0218, which is
converted to decimal distance value: 536 cm. The last byte is the decimal part,
0x32 equals 50 in decimal, that is, 50*1/256cm=0.1953125cm. Then the two
parts add up to 536. 1953125cm.
Byte 7 represents the first echo strength, and the value range is 0-255. (Echo
strength can reflect the energy reflection characteristics of the measured object
in the actual measurement environment. Therefore, the echo strength can be
used to distinguish objects with different reflection characteristics.)
Note: There are 4 more bytes of distance value and intensity information in dual
echo mode than in single echo mode. (for more information, see 5.1.2 subframe)
Byte 8, Byte 9 and Byte 10 represent the secondary echo distance value. Their
data are stored in Big-Endian mode. The two high bytes are the integer part,
whose unit is “cm”; and the last byte is the decimal part, whose unit is 1/256 cm.
The distance value analysis method is the same as the first echo.
Byte 11 represents the second echo strength, and the value range is 0-255.
(Echo strength can reflect the energy reflection characteristics of the measured
object in the actual measurement environment. Therefore, the echo strength can
be used to distinguish objects with different reflection characteristics.)
7.4 Cartesian Coordinate Representation
In order to obtain the vertical angle, horizontal angle and distance parameters of
the Lidar, the angle and distance information in polar coordinates can be
converted to the x, y, z coordinates in the right-hand Cartesian coordinate
system. The conversion relationship is shown in the following formula:
{
𝑥=𝑟 cos𝛼 cos𝜃;
𝑦=𝑟cos𝛼 sin𝜃;
𝑧=𝑟sin𝛼
In the above formula, r is the distance, α is the vertical angle, θ is the horizontal
rotation angle (the horizontal correction angle needs to be considered when
calculating). And x, y, and z are the coordinates of the polar coordinates