In lat long altitude coordinates how is altitude specified?

Question

I want to convert lat long attitude of a place to ECEF coordinates.

Answer 1

altitude is given as meters or feet above sea level

altitude is not part of latitude and longitude.



A GPS machine gives altitude so it can compute the correct latitude & longitude.



Once you have a set of lat/long you can convert it to any other system.

No matter what system you use the altitude is a constant (does not change)

Answer 2

It depends.

Sometimes above nominal sea level, sometimes above an imaginary surface called the geoid, which depends on the projection. As I recall, GPS uses the WGS84 geoid.

Answer 3

In so many metres or feet, +MSL (this is very popular, unless you are designing the dynamics of launch of a Space Probe).

{MSL = Mean Sea Level}