  3D style transfer aims to render stylized novel views of a 3D scene with
multi-view consistency. However, most existing work suffers from a three-way
dilemma over accurate geometry reconstruction, high-quality stylization, and
being generalizable to arbitrary new styles. We propose StyleRF (Style Radiance
Fields), an innovative 3D style transfer technique that resolves the three-way
dilemma by performing style transformation within the feature space of a
radiance field. StyleRF employs an explicit grid of high-level features to
represent 3D scenes, with which high-fidelity geometry can be reliably restored
via volume rendering. In addition, it transforms the grid features according to
the reference style which directly leads to high-quality zero-shot style
transfer. StyleRF consists of two innovative designs. The first is
sampling-invariant content transformation that makes the transformation
invariant to the holistic statistics of the sampled 3D points and accordingly
ensures multi-view consistency. The second is deferred style transformation of
2D feature maps which is equivalent to the transformation of 3D points but
greatly reduces memory footprint without degrading multi-view consistency.
Extensive experiments show that StyleRF achieves superior 3D stylization
quality with precise geometry reconstruction and it can generalize to various
new styles in a zero-shot manner.
