Return Order

Overview

Rev 7 sensors can detect up to two returns from each target. This is a hardware-level capability, independent of the udp_profile_lidar selection — the sensor detects up to two returns in Single Return, Dual Return, and Low Data Rate modes.

Firmware 3.1 added the ability to sort those returns by user-selected criteria (signal strength or range), letting users tune sensor output to the needs of their application.

Sorting Returns

Regardless of the udp_profile_lidar selection (Single Return, Dual Return, or Low Data Rate), the sensor processes two returns internally. Configure the sort via return_order (see POST /api/v1/sensor/config in the API reference for the full schema). The setting applies across all profiles:

• RNG19_RFL8_SIG16_NIR16 (Single Return)
• RNG15_RFL8_NIR8 (Low Data Rate)
• RNG19_RFL8_SIG16_NIR16_DUAL (Dual Return)

The sensor returns the two strongest signals for each radial beam. The order of those two returns in the output depends on return_order:

• STRONGEST_TO_WEAKEST (default) — strongest signal first, then the next strongest. Prioritizes the most reflective or prominent objects. Useful when signal strength is the dominant criterion.
• FARTHEST_TO_NEAREST — sorts by range, farthest first. Useful when the spatial layout of the scene matters (e.g., mapping).
• NEAREST_TO_FARTHEST — sorts by range, nearest first. Useful for nearby obstacle detection.

Note: When min_range_threshold_cm is set to 30 cm or less, set return_order to FARTHEST_TO_NEAREST, especially when udp_profile_lidar is set to a single-return profile.

Choice of order depends on the application. For obstacle detection, NEAREST_TO_FARTHEST surfaces nearby targets first. For mapping, FARTHEST_TO_NEAREST better captures spatial layout.