Representation of rolling shutter within EWA splatting

Determine how to represent time-dependent rolling shutter camera effects within the EWA splatting formulation used to project 3D Gaussian particles onto the image plane in 3D Gaussian Splatting, so that the rasterization approach can accommodate rolling shutter.

Background

3D Gaussian Splatting relies on EWA splatting, which approximates non-linear camera projections via Jacobian-based linearization. This leads to approximation errors under distortion and requires a single projection function.

Rolling shutter introduces time-dependent camera motion during exposure, making the projection function vary across scanlines. The authors explicitly note that within the EWA splatting framework it is unclear how to represent such time-dependent effects; their proposed Unscented Transform formulation sidesteps this by projecting sigma points with varying extrinsics.