What distance does distanceTo returns?

问题:

Does it take into account altitude changes?

I mean, if I start in left vertex of this triangle and end in the right upper vertex, does it return distance a or b?

double distanceInMetersFloat = initialPosition.distanceTo(finalPosition);

In my app, both initialPosition and finalPosition are Location with altitudes (I set them with Google Elevation API).

According to Google:

Distance is defined using the WGS84 ellipsoid.

But you can do it with or without altitudes.

回答1:

The altitude is not taken into account when computing Location.distanceTo.

You can test it like this:

Location location1 = new Location("");
location1.setLatitude(40);
location1.setLongitude(-4);
location1.setAltitude(0);

Location location2 = new Location("");
location2.setLatitude(30);
location2.setLongitude(-3);
location2.setAltitude(0);

Location location3 = new Location("");
location3.setLatitude(30);
location3.setLongitude(-3);
location3.setAltitude(100);

Log.e("Without altitude", ""+location1.distanceTo(location2));
Log.e("With altitude", ""+location1.distanceTo(location3));
Log.e("Different altitude", ""+location2.distanceTo(location3));

This is the output:

E/Without altitude﹕ 1113141.5

E/With altitude﹕ 1113141.5

E/Different altitude﹕ 0.0