Frequently Asked Questions
Q1: Is the LiDAR device eye-safe?
A1: Yes all our LiDARs are eye-safe. However, we recommend that users not stare into the sensor at any time.
Q2: How is the LiDAR powered?
A2: Our R2D LiDARs are powered via USB, the same USB that is used for data and control.
Q3: How do I get data from the LiDAR?
A3: All data is acquired via USB using a simple message protocol described here:
If you can write a program that reads a serial port, then most likely you can write a program for the LiDAR.
Q4: Do you have example code for using the LiDAR?
A4: Yes, we provide an open-source driver for ROS, written in C++. See:
Users who are not using ROS can refer to this driver for details of how to interface to the device.
Q5: Why does my scanner show noise in the scan data?
A5: The Rhoeby R2D LiDAR provides completely unfiltered scan results, when used with it’s default setting. As a result, users may find that there is significant noise in the scan data, as well as “veiling” effects around edges, and other such artifacts. These effects can be eliminated to a great extent by enabling “sample rejection”. This can be done when invoking the ROS driver, as follows:
rosrun scanner2d scanner2d _sample_rejection:=1
Doing the above will result in similar readings to that given by other devices. When doing lab tests, and especially if doing side-by-side comparisons with laser-based devices, it is recommended that users enable sample rejection, as described above.
Q6. How reliable is the device?
A6. We have done several soak tests, to prove the reliability. For example: several units were run for two weeks continuously with no problems. One of our units was run for > 56 days continuously, again without failure. Also, we have units operating in the field, and none have been reported as failing. We do provide a 30-day return policy.
Q7. Can the R2D LiDAR work outside?
A7. The device does not operate well outside (direct sunlight interferes with it). Regarding enclosure: the upper part of the device must have a clear view of the area being scanned. It’s possible to place a cage over it, but with the result that there would be some blind spot (could be made quite minimal).
Q8. When I set the scan rate (eg. _scan_rate:= 4), there are warnings popping out: why is that?
A8. If you want to set the scan rate, it is best to also adjust the number of samples per scan. Like this:
rosrun scanner2d scanner2d _port_name:="/dev/ttyACM0" _samples_per_scan:=250 _scan_rate:=4
The reason is that the scanner can scan at a maximum of 1000 samples per second. When you set _scan_rate:=4, but do not adjust the _samples_per_scan (default is 333), you are asking the scanner to take:
4 * 333 = 1332 samples per second
The above number of 1332 is above 1000, and therefore exceeds the capabilities of the scanner. The scanner will continue to work in this configuration, but some of the samples will be duplicates.
Q9. What is the maximum scan rate that I can set?
A9. The maximum scan rate you can set is 5 scans per second. When setting that, it is best to also reduce the samples per scan, this time it should be set to 1000/5 = 200. So for the maximum scan rate of 5, please invoke the driver like this:
rosrun scanner2d scanner2d _port_name:="/dev/ttyACM0" _samples_per_scan:=200 _scan_rate:=5
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