EventSpecPS: Photometric Stereo with Multispectral Reflectance Using an Event Camera

Surface geometry and multispectral reflectance estimation are essential tools for reliable physical scene understanding in applications such as industrial inspection, cultural heritage analysis, and remote sensing. To obtain dependable spectral and geometric information, conventional pipelines often require multiple multispectral images captured across viewpoints, or multispectral photometric stereo with repeated, sequential illuminations. These approaches are frequently bandwidthintensive and slow to acquire due to their staged capture protocols. We propose EventSpecPS, an event-based multispectral photometric stereo system. It comprises a Spectrally-Angularly Multiplexed Encoding Device that encodes geometric and spectral cues into the event stream, which are then decoded by an Event-based Spectral-Angular Decoder to jointly recover surface normals and absolute multispectral reflectance. This enables single-stage, high-speed, and low-bandwidth acquisition and reconstruction, while remaining robust to cast shadows and specularities in practice. Extensive experiments on both synthetic and real data demonstrate state-of-the-art performance over existing methods. Code and data are available at https://github.com/Wujingqian/EventSpecPS.