Lightweight Spatiotemporal Highway Lane Detection via 3D-ResNet and PINet with ROI-Aware Attention
Authors: Sorna Shanmuga Raja, Abdelhafid Zenati
Organizations: Engineering Department, School of Science and Technology (SST), City, St George’s University of London, Northampton Square, London, EC1V 0HB, United Kingdom.
This paper presents a lightweight, end-to-end highway lane detection architecture that jointly captures spatial and temporal information for robust performance in real-world driving scenarios. Building on the strengths of 3D convolutional neural networks and instance segmentation, we propose two models that integrate a 3D-ResNet encoder with a Point Instance Network (PINet) decoder. The first model enhances multi-scale feature representation using a Feature Pyramid Network (FPN) and Self-Attention mechanism to refine spatial dependencies. The second model introduces a Region of Interest (ROI) detection head to selectively focus on lane-relevant regions, thereby improving precision and reducing computational complexity. Experiments conducted on the TuSimple dataset (highway driving scenarios) demonstrate that the proposed second model achieves 93.40% accuracy while significantly reducing false negatives. Compared to existing 2D and 3D baselines, our approach achieves improved performance with fewer parameters and reduced latency. The architecture has been validated through offline training and real-time inference in the Autonomous Systems Laboratory at City, St George's University of London. These results suggest that the proposed models are well-suited for integration into Advanced Driver Assistance Systems (ADAS), with potential scalability toward full Lane Assist Systems (LAS).
Figures & tables
Fig. 1 : Proposed Network 1.
Fig. 2 : Proposed Network 2.
Attribute
Details
Training Clips
3,626
Testing Clips
2,782
Frames per Clip
20
Resolution
1280×720 pixels
Annotations
Lane point coordinates (JSON format)
Scenario
Multi-lane highway driving scenes
TABLE I : Overview of TuSimple Dataset
Fig. 3 : (a) Lane annotation overlay, (b) mask visualisation.
Mechanism
Description
Limitation
Spatial Attention
Emphasises informative spatial regions
Limited long-range dependency modelling
Channel Attention
Reweights feature channels
Does not explicitly model spatial relationships
Self-Attention
Models global feature interactions
Higher computational complexity
TABLE II : Comparison of Attention Mechanisms
Layer
Resolution
Information Captured
1st (shallow)
128×256
Fine-grained spatial structures and edge-level details
2nd
64×128
Mid-level texture and structural representations
3rd
32×64
Higher-order feature abstractions and pattern compositions
4th (deepest)
16×32
High-level semantic representations and contextual encoding
TABLE III : Progression of Feature Maps in FPN
Fig. 4 : PINet implementation with multi-branch outputs.
Fig. 5 : ROI implementation and integration with loss functions.
Fig. 6 : Post-processing pipeline with RANSAC and graph-based smoothing.
Exp.
Model
Enhancements
1
3D-ResNet + PINet (Base Arch.)
Baseline configuration with RANSAC post-processing and graph-based smoothing
2
+ Self-Attention + FPN
Multi-scale feature fusion with multi-branch supervision
3
+ ROI + Focal + LineIoU
ROI-driven refinement with focal loss optimisation and improved lane alignment consistency
TABLE IV : Summary of Experimental Configurations
Fig. 7 : Results of Experiment 1: lane predictions, training stability, and confusion matrix.
Fig. 8 : Results of Experiment 2: lane predictions, training stability, and confusion matrix.
Fig. 9 : Results of Experiment 3: lane predictions, training stability, and confusion matrix.
Fig. 10 : Results of Experiment 4: lane predictions, training stability, and confusion matrix.
Monocular 3D lane detection plays a critical role in autonomous driving, yet recovering reliable 3D geometry from a single image remains challenging due to inherent depth ambiguity. Prior methods project image features into Bird's-Eye-View (BEV) space under a flat-ground assumption, causing geometric distortion on real-world roads. Recent methods instead predict explicit height maps to capture non-planar surfaces, but still rely on sparse anchor-based regression and exploit the recovered geometry merely for spatial transformation rather than semantic understanding. To overcome these limitations, we propose HSDF-Lane, which implicitly models the road surface as a Height-aligned Signed Distance Field (HSDF) over a densely sampled 3D feature volume. Through differentiable rendering, the HSDF jointly produces an accurate height map and surface-aligned features. We further introduce Lane-aware Semantic Positional Encoding (LSPE), which injects a lane-existence prior derived from the surface-aligned features into the transformer queries, coupling geometric structure with semantic guidance. Extensive experiments on the OpenLane benchmark show that HSDF-Lane achieves state-of-the-art performance in both 3D lane detection and height map estimation.
Lane boundary detection is a critical component in autonomous driving systems and has been rigorously studied in regular driving scenarios. However, it is less explored in vehicle racing, where the car moves at higher speeds across more extreme road geometries. To study this problem, we introduce a new dataset for 3D lane detection in racing, featuring >250k images from multiple camera feeds and inertial measurements taken with a Lexus LC 500 driving on a closed circuit. With this dataset, we compare various approaches to 3D lane detection and propose modifications that permit frames to be processed at rates of almost 300Hz while retaining high predictive performance in the racing application. This facilitates a multi-camera ensemble approach that is validated on hardware. We show that sensing modalities such as inertial measurements can be leveraged for pre-integration to regress road geometries over both cameras and time, yielding improvements in key metrics. Compared to methods such as BevLaneDet, adding odometry and ensemble predictions improves the F1 score by 3 points and reduces near-vehicle mean absolute errors (MAEs) by >30%. We show F1 scores >0.9 and lateral MAEs of <0.18m in vehicle deployments.
Omoruyi Atekha, John Subosits, Marcus Greiff
Massachusetts Institute of Technology (MIT), Cambridge, MA, USA. · Toyota Research Institute (TRI), 94022 Los Altos, CA, USA.
Real-time 3D object detection is a critical component for the safe operation of autonomous driving systems and robotics. While LiDAR point clouds provide accurate spatial information, processing them efficiently remains a significant challenge. Traditional methods rely on complex 3D convolutions or anchor-based paradigms that struggle to balance detection accuracy with inference speed. In this paper, we propose PillarDETR, a novel end-to-end 3D object detection architecture that combines the efficiency of pillar-based LiDAR encoding with the representational power of modern 2D vision models. Specifically, PillarDETR replaces standard convolutional backbones with a Cross Stage Partial (CSP) network derived from YOLOv8, enabling richer feature extraction from pseudoimages. Furthermore, we discard conventional anchor-based or center-based detection heads in favor of a Real-Time Detection Transformer (RT-DETR) decoder. This hybrid design allows the network to capture global context and directly predict 3D bounding boxes without relying on non-maximum suppression (NMS). Extensive experiments on the KITTI and nuScenes benchmarks demonstrate that PillarDETR achieves a compelling trade-off between mean Average Precision (mAP) and inference latency. Our ablation studies confirm that integrating the YOLOv8 backbone and RT-DETR head yields substantial improvements over the PointPillars baseline, establishing PillarDETR as a highly effective solution for real-time 3D perception.
Smit Kadvani, Shriya Gumber, Kriti Faujdar +1
Independent Researcher · University of Southern California · Illinois Institute of Technology