RoofSense: A Multimodal Semantic Segmentation Dataset for Roofing Material Classification

Abstract. Roofing material classification is critical for urban sustainability, energy efficiency, public health, environmental protection, and regulatory compliance. Despite the need for scalable solutions, existing approaches are hindered by reliance on oftentimes expensive and rare multi- or hyper-spectral satellite imagery, application-specific assumptions and biases, and oversight of deep learning and multimodal data fusion. This paper addresses these gaps by introducing RoofSense, a multimodal semantic segmentation dataset for roofing material classification in diverse urban contexts, leveraging 8 cm aerial true-color imagery and airborne laser scanning data. Representing eight classes and encompassing over 138 ha and 480 buildings across five Dutch cities, RoofSense is the largest publicly available dataset of its kind. By combining spectral and geometric information at the pixel level and adopting a novel weighting scheme to address class imbalance, RoofSense can be used to achieve competitive classification and segmentation performance in downstream tasks. This was demonstrated in a comprehensive purpose-designed benchmarking experiment with an off-the-shelf model based on ResNet-18-D and DeepLabv3+. Although lidar-derived features improved performance in difficult classes and materials commonly used on pitched roofs, results were sensitive to material and building context, clutter, and modality alignment, indicating that the theoretical benefits of data fusion are not straightforward. The implementation is publicly accessible at https://github.com/DimitrisMantas/RoofSense.