  Our objective is to leverage a differentiable radiance field \eg NeRF to
reconstruct detailed 3D surfaces in addition to producing the standard novel
view renderings. There have been related methods that perform such tasks,
usually by utilizing a signed distance field (SDF). However, the
state-of-the-art approaches still fail to correctly reconstruct the small-scale
details, such as the leaves, ropes, and textile surfaces. Considering that
different methods formulate and optimize the projection from SDF to radiance
field with a globally constant Eikonal regularization, we improve with a
ray-wise weighting factor to prioritize the rendering and zero-crossing surface
fitting on top of establishing a perfect SDF. We propose to adaptively adjust
the regularization on the signed distance field so that unsatisfying rendering
rays won't enforce strong Eikonal regularization which is ineffective, and
allow the gradients from regions with well-learned radiance to effectively
back-propagated to the SDF. Consequently, balancing the two objectives in order
to generate accurate and detailed surfaces. Additionally, concerning whether
there is a geometric bias between the zero-crossing surface in SDF and
rendering points in the radiance field, the projection becomes adjustable as
well depending on different 3D locations during optimization. Our proposed
\textit{RaNeuS} are extensively evaluated on both synthetic and real datasets,
achieving state-of-the-art results on both novel view synthesis and geometric
reconstruction.
