Comment by ericpauley
Comment by ericpauley 2 days ago
This is not the correct way to count digit precision, which should be independent of the units used. If there were 360,000 degrees in a circle would this same precision suddenly be 4 digits? If we measured in radians would the digit precision become 9? Of course not…
Given the 100ndeg precision is across the full earth, this would be 1 part per 3.6 billion or 9.5ish digits of precision. The location of the decimal point when displaying it is irrelevant.
What also needs to be taken into account is that real world longitudinal distance changes by the cosine of latitude. 1 degree of longitude is 111km at the equator and 19km at 80 degrees.
In GIS the gold standard for positional accuracy is the Root Mean Square Error, measured in real world distance units.