Splatting SA: Direct Rendering of Synthetic Aperture Imagery

Synthetic aperture radar and sonar imaging based on conventional signal processing techniques are now mature technologies capable of producing high-quality images. When combined with 2D and 3D rendering techniques, they can yield highly engaging visualizations. In the field of optical 3D reconstruction, direct rendering approaches have been popularized by methods such as neural radiance fields and Gaussian splatting. Inspired by this, we propose a novel direct rendering approach to synthetic aperture imaging that performs conventional synthetic aperture signal accumulation directly in camera space. In our method, a camera observer is defined, and ray marching is employed to determine the imaging coordinates. A signal primitive representation is introduced, and each signal is coherently delayed and summed in a highly parallelizable manner. The output is a raster image render generated from the perspective defined by the camera model, with full synthetic aperture processing gain but without the explicit beamforming and intermediate processing steps characteristic of conventional synthetic aperture techniques. Our proposed method is a proof of concept applicable to a range of use cases, including interactive data inspection with dynamic processing adjustments and real-time visualization of incoming data streams. We demonstrate its effectiveness on real synthetic aperture sonar and radar datasets.