Comment by jacquesm
1 month ago
Near ore deposits the map resolution needs to go up considerable beyond the 'few KB of data' to keep it working. Nautical charts are simpler because there is as a rule a bit more distance between the compass and any anomalies but in certain mineral rich areas of the world that definitely is not the case.
Thanks. I was mostly basing my answer on my experience with nautical charts, where declination corrections are typically uniform over relatively large areas and local anomalies are less of a concern. I hadn’t considered how much more variable the field can be in terrestrial use.