# Deep Learning and Geometric Modeling for 3D Reconstruction of Subsurface Utilities from GPR Data

## TL;DR

This paper introduces a deep learning pipeline for 3D mapping of underground utilities using GPR data, improving accuracy and practicality for real-world applications.

## Contribution

The novel hybrid model uses real-world data, detects summit points directly, and applies geometric modeling for 3D utility reconstruction.

## Key findings

- Mask R-CNN outperformed YOLO models with an F1-score of 0.822 for keypoint detection and 0.867 for bounding boxes.
- 3D DBSCAN clustering and RANSAC line fitting achieved an average RMSE of 0.06 for reconstructed utility paths.
- The method avoids synthetic data and full 3D volumes, improving generalizability and scalability in real-world conditions.

## Abstract

Accurate underground utility mapping remains a critical yet complex task in Ground Penetrating Radar (GPR) interpretation, essential to avoiding costly and dangerous excavation errors. This study presents a novel deep learning-based pipeline for 3D reconstruction of buried linear utilities from high-resolution GPR B-scan data. Three state-of-the-art models—YOLOv8, YOLOv11, and Mask R-CNN—were employed for both bounding box and keypoint detection of hyperbolic reflections, using a real-world GPR dataset. On the test set, Mask R-CNN achieved the highest keypoint F1-score (0.822) and bounding box F1-score (0.867), outperforming the YOLO models. Detected summit points were clustered using a 3D DBSCAN algorithm to approximate the spatial trajectories of buried utilities. RANSAC-based line fitting was then applied to each cluster, yielding an average RMSE of 0.06 across all fitted 3D paths. The key innovation of this hybrid model lies in its use of real-world data (avoiding synthetic augmentation), direct summit point detection (beyond bounding box analysis), and a geometric 3D reconstruction pipeline. This approach addresses key limitations in prior studies, including poor generalizability to complex real-world scenarios and the reliance on full 3D data volumes. Our method offers a more practical and scalable solution for subsurface utility mapping in real-world settings.