Retro-reflection Tracking

Overview

LiDARs use laser beams to collect 3D data of their surroundings. The data returned is a cloud of points with 3D coordinates and an intensity value. The intensity value is the intensity of the reflected laser beam received by the LiDAR.

Retro-reflective materials return laser beams with high intensity values, allowing to discriminate them from common ones.

SENSR can highlight retro-reflective objects to differentiate them from regular ones. The feature can be found in the following menu: Settings > Advanced Features > Retro-reflection Tracking

Retro-reflection tracking

Retro-reflection tracking defines an intensity threshold at which LiDAR points are considered retro-reflective. SENSR then uses this value to differentiate covered with retro-reflective material from regular objects.

For instance, this function can be used for highlighting workers wearing retro-reflective vests.

LiDARs do not have a standardized intensity range, the right value for a given LiDAR must be set case by case. The way to proceed is by starting with a low value and increasing it until the noise is filtered out.

Activate Retro-reflection Tracking

0. In the menu, navigate to Settings > Advanced Feature > Retro-reflection Tracking

1. Tick Enable Retro-Reflection Tracking

2. Tick Draw Retro-Reflective Objects, to be able to visually to differentiate retro-reflective objects from regular ones. The displayed color can be updated here View > Preferences > Color.

3. Input Retro-Reflective Intensity value for each sensor. The values are different by sensors, so tune the value during runtime to get the exact retro-reflective value of your sensor.

4. Click Apply

note

Don't forget to turn on Enable Retro-Reflection Tracking and Draw Retro-Reflective Objects to visualize retro-reflective objects. You can enable at the Settings > Advanced Features > Retro-reflection Tracking window as well as View > Preference > Visibility

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Appendix. Quick peek of Intensity Value by sensors

Those values are generated by SeoulRobotics as of June, 2022. We recommend using those values as reference only.

For more exact values: please see here.

Manufacturer	Intensity Width	Retro-reflective Value
Velodyne	0-255	230
Hesai	0-255	230
Ouster	2-7000	6200
Opsys	0-255	230
Livox	0-255	230
Luminar	0-1	0.8
Innovusion	0-255	230
Blickfeld	3E-44 ~ 7E-42	6.31E-42