alpha-beta-soup
commented
2 months ago As far as distortions from map projections go, discrete global grid systems do indeed avoid "all of the distortions inherent in map projections". (Not considering a visualisation layer.)
Rather than lay a quadtree on a flattened Earth, DGGs are hierarchical structures on the curved surface of the Earth itself, thus avoiding all of the distortions inherent in map projections.
https://doi.org/10.1080/19475683.2018.1424737
There are of course shape and area distortions associated with different DGGSs, this is why we used weaker language than Goodchild ("meliorate" rather than "avoiding all"). I have expanded our description to include mention of area and shape distortions in DGGSs, and relevant supporting citations, especially to: https://doi.org/10.1080/20964471.2022.2094926
While true that traditional GIS will have distortion errors associated with their map distortions, DGGS are not free of distortions. The distortions arising from choice of DGGS generally arise from the underlying choice of the pythagorean solid used to represent the 3d nature of the Earth. Whereas spatial distortions arising from projections can be both symmetrical and non-linear (e.g. increasing when moving away from the Equator) spatial distortions arising from use of DGGS will depend on the type of pythagorean solid and the location of geographicfeatures within particular cells (e.g within H3, spatial distortions would vary depending if a feature was in a hexagonal or pentagonal cells). Within other DGGS, distortions arise as a result of interactions between the pythagorean solid, the location of the Earth that is being represented, and the analytical need of a particular study. rHEALPix, for example, is badly distorted at the poles in both the northern and southern hemispheres. Thus, it is a poor choice for studying or understanding changes in ice dynamics in a changing climate, for instance.
The main point I am making is that there are spatial distortions with DGGS, but they are theoretically fewer in number, though potentially harder to quantify and describe. An acknowledgment of that would not go astray, no would it undermine the points the authors wish to convey. Perhaps a brief mention that DGGS do remove some distortions of traditional projections, the distortions associated with DGGS themselves are somewhat understudied. The hope is that by having more points of contact between the Earth surface and the underlying model for the surface that overall distortion is reduced.