Comprehensive Assessment of LiDAR Evaluation Metrics: A Comparative Study Using Simulated and Real Data

TL;DR

This study evaluates various metrics for comparing real and simulated LiDAR data to improve virtual testing environments for autonomous driving, finding Density Aware Chamfer Distance most effective.

Contribution

It introduces a comprehensive experimental approach to identify suitable evaluation metrics for LiDAR simulation accuracy, highlighting the effectiveness of DCD across different conditions.

Findings

DCD outperforms other metrics in sensitivity and accuracy

Simulated and real LiDAR scans show similar semantic segmentation outputs

DCD correlates strongly with perception model performance

Abstract

For developing safe Autonomous Driving Systems (ADS), rigorous testing is required before they are deemed safe for road deployments. Since comprehensive conventional physical testing is impractical due to cost and safety concerns, Virtual Testing Environments (VTE) can be adopted as an alternative. Comparing VTE-generated sensor outputs against their real-world analogues can be a strong indication that the VTE accurately represents reality. Correspondingly, this work explores a comprehensive experimental approach to finding evaluation metrics suitable for comparing real-world and simulated LiDAR scans. The metrics were tested in terms of sensitivity and accuracy with different noise, density, distortion, sensor orientation, and channel settings. From comparing the metrics, we found that Density Aware Chamfer Distance (DCD) works best across all cases. In the second step of the research, a Virtual Testing Environment was generated using real LiDAR scan data. The data was collected in a controlled environment with only static objects using an instrumented vehicle equipped with LiDAR, IMU and cameras. Simulated LiDAR scans were generated from the VTEs using the same pose as real LiDAR scans. The simulated and LiDAR scans were compared in terms of model perception and geometric similarity. Actual and simulated LiDAR scans have a similar semantic segmentation output with a mIoU of 21\% with corrected intensity and an average density aware chamfer distance (DCD) of 0.63. This indicates a slight difference in the geometric properties of simulated and real LiDAR scans and a significant difference between model outputs. During the comparison, density-aware chamfer distance was found to be the most correlated among the metrics with perception methods.