High-accuracy data collection has come a long way since the USA launched the first GNSS constellation, GPS, in the 1970s. Today, all you need to get started with submeter or centimeter data collection is a smart device, a collection app, and a GNSS receiver that works with both.
Elevation is the difference between the earth’s surface and a point above or below it. But the earth’s surface isn’t the same everywhere. It’s full of physical features, like mountains and valleys. So how can we measure elevation? Explore how in the latest Learning Center article from the Eos January 2018 issue.
What is the difference between the ellipsoid, mean sea level, geoid, geoid height, and orthometric height — and which one is right? Learn how the ellipsoid elevation your GPS receiver captures relates to the geoid, how to convert between the two so you can start using your data, and why most GPS receivers don't output the orthometric height you rely on.
Unmanned air vehicles can collect tremendous data and imagery to produce high-precision orthophotos. But how can you set up your own GCPs to ensure precision and accuracy? This article from the Eos June 2017 issue explains how.