How I created an API to correct GPS to Sea Level.
A simple solution to a complicated problem.
The Problem
GPS is wonderful!
But it has problems with altitude!
Very simply:
- Vertical GPS measurements are just less accurate (because of geometry), and
- We don’t know where the surface of the Earth is!
Putting aside the first (since fixing geometry is beyond the scope of the article :), this article documents how to create a solution for “finding the surface of the Earth” or more accurately how to convert from GPS coordinates to a height above Mean Sea Level (MSL) which is defined for the purpose of this API as the WGS84 Orthometric Height.
What is GPS’ problem with altitudes?
I previously investigated the problems analysing and using GPS altitudes, especially on smartphones and other small devices, in this article:
NOTE — throughout this article I will talk about GPS. I should actually be…