The IsoEss filter detects outliers in manifold-like structures using Isomap (https://en.wikipedia.org/wiki/Isomap) and LOWESS (https://en.wikipedia.org/wiki/Local_regression).
IsoEss is part of Brain Cell Finder (https://github.com/paolo-f/bcfind), and it is described in [1], section 2.4 "Manifold modeling".
[1] Frasconi, P., Silvestri, L., Soda, P., Cortini, R., Pavone, F. S., & Iannello, G. (2014). Large-scale automated identification of mouse brain cells in confocal light sheet microscopy images. Bioinformatics, 30(17), i587–i593. http://doi.org/10.1093/bioinformatics/btu469.