SALENet: Structure-Aware Lighting Estimations From a Single Image for Indoor Environments

High Dynamic Range (HDR) lighting plays a pivotal role in modern augmented and mixed-reality (AR/MR) applications, facilitating immersive experiences through realistic object insertion and dynamic relighting. However, the acquisition of precise HDR environment maps remains cost-prohibitive and impractical when using standard devices. To bridge this gap, this paper introduces SALENet, a novel deep network for estimating global lighting conditions from a single image, to effectively mitigate the need for resource-intensive acquisition methods. In contrast to earlier studies, we focus on exploring the inherent structural relationships within the lighting distribution. We design a hierarchical transformer-based neural network architecture with a proposed cross-attention mechanism between different resolution lighting source representations, optimizing the spatial distribution of lighting sources simultaneously for enhanced consistency. To further improve accuracy, a structure-based contrastive learning method is proposed to select positive-negative pairs based on lighting distribution similarity. By harnessing the synergy of hierarchical transformers and structure-based contrastive learning, our framework yields a significant enhancement in lighting prediction accuracy, enabling high-fidelity augmented and mixed reality to achieve cost-effectively immersive and realistic lighting effects.