  We propose a new strategy to bridge point cloud denoising and surface
reconstruction by alternately updating the denoised point clouds and the
reconstructed surfaces. In Poisson surface reconstruction, the implicit
function is generated by a set of smooth basis functions centered at the
octnodes. When the octree depth is properly selected, the reconstructed surface
is a good smooth approximation of the noisy point set. Our method projects the
noisy points onto the surface and alternately reconstructs and projects the
point set. We use the iterative Poisson surface reconstruction (iPSR) to
support unoriented surface reconstruction. Our method iteratively performs iPSR
and acts as an outer loop of iPSR. Considering that the octree depth
significantly affects the reconstruction results, we propose an adaptive depth
selection strategy to ensure an appropriate depth choice. To manage the
oversmoothing phenomenon near the sharp features, we propose a
$\lambda$-projection method, which means to project the noisy points onto the
surface with an individual control coefficient $\lambda_{i}$ for each point.
The coefficients are determined through a Voronoi-based feature detection
method. Experimental results show that our method achieves high performance in
point cloud denoising and unoriented surface reconstruction within different
noise scales, and exhibits well-rounded performance in various types of inputs.
The source code is available
at~\url{https://github.com/Submanifold/AlterUpdate}.
