Camera Perspective Transformation to Bird's Eye View via Spatial Transformer Model for Road Intersection Monitoring

Road intersection monitoring and control research often utilize bird's eye view (BEV) simulators. In real traffic settings, achieving a BEV akin to that in a simulator necessitates the deployment of drones or specific sensor mounting, which is neither feasible nor practical. Consequently, traffic intersection management remains confined to simulation environments given these constraints. In this paper, we address the gap between simulated environments and real-world implementation by introducing a novel deep-learning model that converts a single camera's perspective of a road intersection into a BEV. We created a simulation environment that closely resembles a real-world traffic junction. The proposed model transforms the vehicles into BEV images, facilitating road intersection monitoring and control model processing. Inspired by image transformation techniques, we propose a Spatial-Transformer Double Decoder-UNet (SDD-UNet) model that aims to eliminate the transformed image distortions. In addition, the model accurately estimates the vehicle's positions and enables the direct application of simulation-trained models in real-world contexts. SDD-UNet model achieves an average dice similarity coefficient (DSC) above 95% which is 40% better than the original UNet model. The mean absolute error (MAE) is 0.102 and the centroid of the predicted mask is 0.14 meters displaced, on average, indicating high accuracy.