  The advent of neural and Gaussian-based radiance field methods have achieved
great success in the field of novel view synthesis. However, specular
reflection remains non-trivial, as the high frequency radiance field is
notoriously difficult to fit stably and accurately. We present a deferred
shading method to effectively render specular reflection with Gaussian
splatting. The key challenge comes from the environment map reflection model,
which requires accurate surface normal while simultaneously bottlenecks normal
estimation with discontinuous gradients. We leverage the per-pixel reflection
gradients generated by deferred shading to bridge the optimization process of
neighboring Gaussians, allowing nearly correct normal estimations to gradually
propagate and eventually spread over all reflective objects. Our method
significantly outperforms state-of-the-art techniques and concurrent work in
synthesizing high-quality specular reflection effects, demonstrating a
consistent improvement of peak signal-to-noise ratio (PSNR) for both synthetic
and real-world scenes, while running at a frame rate almost identical to
vanilla Gaussian splatting.
