Here is a small evidence of why one should rather avoid mapping “individual” dunes:
they’re usually moving.
Sometimes they may even move across the oceans…
Below is what I could roughly, localy measure, with help from Sentinel & Landsat.
Saharan dunes - Adrar, Algeria
Direction of movement: SW ~200m / 30years
There where the wind turns the corner, at https://www.osm.org/edit#map=6/24.375/-2.875
(or zoom to https://www.osm.org/edit#map=15/24.3750/-2.8750)
(timelapse made with: https://apps.sentinel-hub.com/eo-browser/ - Landsat-5 1987-2011; Sentinel-2 2015-2019)
Harmattan wind (https://en.wikipedia.org/wiki/Harmattan): this wind always goes east-west direction from Sahara, many times throwing parts of the sands it carries on brazilian coasts (https://en.wikipedia.org/wiki/Trade_winds), like at
“Lençóis Maranhenses” National Park, Maranhão, Brazil
Direction of movement: WSW ~200m / 6years
(timelapse made with: https://apps.sentinel-hub.com/eo-browser/ - Landsat-8 pansharpened 2013-2019)
Don’t believe they move as far as that?