help with distance

[csanchez]

Hello i want to know what is the metric for the method distance? i mean the result is in meters, kilometers, miles???

[dazuma]

The metric varies depending on the coordinate system being used. For Cartesian coordinate systems, it is simple Euclidean distance in whatever units you are using. The spherical geographic factory measures distances in meters. If you use a geographic factory with an underlying projection, the "distance" is measured in that projection's units.

[acds]

What about if you want to convert to miles, nautical miles, ft, inches, or boat lengths...

[dazuma]

It depends on what coordinate system you are in. For example, if you're in a standard Mercator projection, the units are generally in meters, but you have to scale up as you increase in latitude. You can look up the formula for your particular projection on a variety of websites. RGeo doesn't try to do this for you because there are so many cases---it's different for every single coordinate system, and that only accounts for the known "standard" coordinate systems (of which there are hundreds).

If you need help with a particular use case, ask on the rgeo-users google group. Someone there (probably me) can point you in the right direction.