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2D Forward Looking Sonar Simulation with Ground Echo Modeling

Yusheng Wang, Chujie Wu, Yonghoon Ji, Hiroshi Tsuchiya, Hajime Asama, Atsushi Yamashita

TL;DR

This work addresses the challenge of realistic 2D forward-looking sonar simulation by explicitly modeling ground echoes and multi-path reflections within a single-bounce framework. By mirroring objects or sensors, the method synthesizes double- and triple-bounce components and integrates them with the standard single-bounce rendering to generate more geometry-consistent acoustic images, validated against a water-tank dataset. Quantitative results show that including triple-bounce ground echoes improves PSNR by approximately 0.54–0.57 dB and modestly improves double-bounce results, while maintaining comparable MSE, indicating enhanced geometric realism. The approach enables more faithful synthetic data for underwater perception tasks, with practical impact on training and evaluating imaging sonar-based robotics systems, though real-time performance remains an area for optimization.

Abstract

Imaging sonar produces clear images in underwater environments, independent of water turbidity and lighting conditions. The next generation 2D forward looking sonars are compact in size and able to generate high-resolution images which facilitate underwater robotics research. Considering the difficulties and expenses of implementing experiments in underwater environments, tremendous work has been focused on sonar image simulation. However, sonar artifacts like multi-path reflection were not sufficiently discussed, which cannot be ignored in water tank environments. In this paper, we focus on the influence of echoes from the flat ground. We propose a method to simulate the ground echo effect physically in acoustic images. We model the multi-bounce situations using the single-bounce framework for computation efficiency. We compare the real image captured in the water tank with the synthetic images to validate the proposed methods.

2D Forward Looking Sonar Simulation with Ground Echo Modeling

TL;DR

This work addresses the challenge of realistic 2D forward-looking sonar simulation by explicitly modeling ground echoes and multi-path reflections within a single-bounce framework. By mirroring objects or sensors, the method synthesizes double- and triple-bounce components and integrates them with the standard single-bounce rendering to generate more geometry-consistent acoustic images, validated against a water-tank dataset. Quantitative results show that including triple-bounce ground echoes improves PSNR by approximately 0.54–0.57 dB and modestly improves double-bounce results, while maintaining comparable MSE, indicating enhanced geometric realism. The approach enables more faithful synthetic data for underwater perception tasks, with practical impact on training and evaluating imaging sonar-based robotics systems, though real-time performance remains an area for optimization.

Abstract

Imaging sonar produces clear images in underwater environments, independent of water turbidity and lighting conditions. The next generation 2D forward looking sonars are compact in size and able to generate high-resolution images which facilitate underwater robotics research. Considering the difficulties and expenses of implementing experiments in underwater environments, tremendous work has been focused on sonar image simulation. However, sonar artifacts like multi-path reflection were not sufficiently discussed, which cannot be ignored in water tank environments. In this paper, we focus on the influence of echoes from the flat ground. We propose a method to simulate the ground echo effect physically in acoustic images. We model the multi-bounce situations using the single-bounce framework for computation efficiency. We compare the real image captured in the water tank with the synthetic images to validate the proposed methods.
Paper Structure (10 sections, 10 equations, 10 figures, 1 table, 2 algorithms)

This paper contains 10 sections, 10 equations, 10 figures, 1 table, 2 algorithms.

Table of Contents

  1. INTRODUCTION
  2. Imaging Model
  3. Geometry Model
  4. Image Formation
  5. Simulation Framework
  6. Ground Echo Modeling
  7. Experiment
  8. Dataset
  9. Results
  10. CONCLUSIONS

Figures (10)

  • Figure 1: Multi-path reflection problem in acoustic image formation. (a) The real sonar image. (b) Illustration of multiple bounces during sonar imaging. (c) The synthetic sonar image generated only considering the single bounce. (d) The synthetic sonar image generated with the proposed method. Our proposed method can generate realistic images by synthesizing the multi-path phenomenon.
  • Figure 2: Imaging principle of the 2D forward looking sonar. (a) Multiple beams in azimuth angle direction. (b) The geometry model.
  • Figure 3: A beam slice during sonar imaging. The beam is separated into rays. The backscattered signal is used to generate the image.
  • Figure 4: The single-bounce simulation framework. The intermediate forms, distance map and intensity map, can be generated using the existing rendering engines. Acoustic images can be calculated from the distance and intensity maps.
  • Figure 5: Explanation of the sampling process. The backscattered signal and the corresponding distance can be stored in two matrices.
  • ...and 5 more figures