SphGaS: Spherical Gaussian Splatting for RF Spectrum Synthesis under Varying Transmitter–Receiver Configurations

This paper proposes SphGaS, a novel Gaussian splatting (GS)-based framework for rendering transmitter–receiver-conditioned (TX-RX) RF spectra directly on the spherical manifold. Existing GS-based methods typically synthesize planar spectra. Geometrically, this is not consistent with the practical spherical structure of the RF spectra, consequently leading to distorted Gaussian responses. Meanwhile, some methods model spectral variations at one transceiver endpoint only, neglecting the coupled variations induced by the TX and/or RX movement. To the best of our knowledge, SphGaS is the first framework that jointly addresses geometric misalignment and TX-RX mobility. It introduces spherical Gaussian primitives that deform with the TX-RX configuration and are rasterized directly in the spherical domain. This design preserves the geometry of Gaussian responses while efficiently capturing the coupled spectrum variations induced by TX–RX movement. With a customized CUDA rasterizer, SphGaS keeps fast rendering while substantially improving the modeling fidelity. Experiments show that SphGaS improves PSNR by 1.49 dB and achieves up to 40X faster rendering than state-of-the-art GS-based methods on real-world RFID datasets.