  We propose a new method for reconstructing controllable implicit 3D human
models from sparse multi-view RGB videos. Our method defines the neural scene
representation on the mesh surface points and signed distances from the surface
of a human body mesh. We identify an indistinguishability issue that arises
when a point in 3D space is mapped to its nearest surface point on a mesh for
learning surface-aligned neural scene representation. To address this issue, we
propose projecting a point onto a mesh surface using a barycentric
interpolation with modified vertex normals. Experiments with the ZJU-MoCap and
Human3.6M datasets show that our approach achieves a higher quality in a
novel-view and novel-pose synthesis than existing methods. We also demonstrate
that our method easily supports the control of body shape and clothes. Project
page: https://pfnet-research.github.io/surface-aligned-nerf/.
