Single Return Mode (either Strongest or Last)
Dual Return Mode
See
Laser Return Modes on page 32
for an illustration of what Strongest, Last, and Dual mean in this context.
The packet data structure for Single Return Mode is shown in
Figure 9-2 below
. The packet data structure for Dual Return
Mode is shown in
Figure 9-3 on the next page
.
There are several key differences between the packet structures.
First, in Dual Return Mode the sensor sends a pair of data blocks for each azimuth angle firing. The odd numbered blocks
(1, 3, ..., 9, 11) contain either the strongest or second-strongest return and the even numbered blocks (0, 2, ..., 8, 10) con-
tain the last return.
If the strongest return is also the last return, then the second-strongest return is provided. If only one return was detected,
the data will be identical in the even|odd block pairs (0|1, 2|3, 4|5, 6|7, 8|9, 10|11).
Figure 9-2 VLP-32 Single Return Mode Data Structure
Chapter 9 • Sensor Data 57
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