Velodyne Acoustics HDL-64E S2.1 user manual Establish communication with the sensor

usaGe HDL-64E S2 and S2.1 User’s Manual

The following provides more detail on each of the above steps.

1. Establish communication with the sensor.

The sensor broadcasts UDP packets. By using a network monitoring tool, such as Wireshark, you can capture and observe the packets as they are generated by the sensor. See Appendix E for the UDP packet format. The default source IP address for the sensor is 192.168.3.043, and the destination IP address is 192.168.3.255. To change these IP addresses, see page 11.

2.Create an internal calibration table either from the calibration data included in-stream from the sensor or from the included db.xml data file.

This table must be built and stored internal to the point-cloud processing software. The easiest and most reliable way to build the calibration table is by reading the calibration data directly from the UDP data packets. A MatLab example of reading and building such a table can be found in Appendix D and on the CD included with the sensor named CALTABLEBUILD.m.

Alternatively, the calibration data can be found in the included db.xml file found on the CD included with the sensor. A description of the calibration data is shown in the following table.

db.xml Calibration Parameters

Parameter	Unit	Description	Values
rotCorrection	degree	The rotational correction angle for each laser,	Positive factors rotate to the left.
		as viewed from the back of the unit.	Negative values rotate to
			the right.
vertCorrection	degree	The vertical correction angle for each laser,	Positive values have the laser
		as viewed from the back of the unit.	pointing up.
			Negative values have the laser
			pointing down.
distCorrection	cm	Far distance correction of each laser distance	Add directly to the distance value
		due to minor laser parts’ variances.	read in the packet.
distCorrectionX	cm	Close distance correction in X of each laser due to
		minor laser parts variances interpolated with far
		distance correction then applied to measurement in X.
distCorrectionY	cm	Close distance correction in Y of each laser due to
		minor laser parts variances interpolated with far
		distance correction then applied to measurement in Y.
vertOffsetCorrection	cm	The height of each laser as measured from	One fixed value for all upper
		the bottom of the base.	block lasers.
			Another fixed value for all lower
			block lasers.
horizOffsetCorrection	cm	The horizontal offset of each laser	Fixed positive or negative value
		as viewed from the back of the laser.	for all lasers.
Maximum Intensity			Value from 0 to 255. Usually 255.
Minimum Intensity			Value from 0 to 255. Usually 0.
Focal Distance		Maximum intensity distance.
Focal Slope		The control intensity amount.

The calibration table, once assembled, contains 64 instances of the calibration values shown in the table above to interpret the packet data to calculate each point’s position in 3D space. Use the first 32 points for the upper block and the second 32 points for the lower block. The rotational info found in the packet header is used to determine the packets position with respect to the 360° horizontal field of view.

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