This is an implementation of the Lp-dist field approach for smoothly approximating the distance to a given surface.
@article{belyaev2013signed, title={Signed Lp-distance fields}, author={Belyaev, Alexander and Fayolle, Pierre-Alain and Pasko, Alexander}, journal={Computer-Aided Design}, volume={45}, number={2}, pages={523--528}, year={2013}, publisher={Elsevier} }