The current version presents following limitations: (I) the resulting channels can only be formed either for positions based on 10–10 or 10–5 extent, i.e. one cannot combine them into a single layout; (II) high-density arrangements for 3D diffuse optical tomography43,44 cannot be automatically generated from within fOLD; (III) the normalized sensitivity is separately calculated on a channel basis and does not accumulate for near channels with eventual overlapping photon transport. These first three limitations mainly concern the possibility of extending the presented approach to appreciate the potential for tomography studies, while the current version of fOLD rather focuses on topography (i.e. in the absence of major overlap of sensitivity profiles of photon transport). Nevertheless, we believe that one can potentially identify the most relevant positions from within fOLD and extend its output to a higher-density of optodes by placing more channels around the retrieved topographical positions.