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.
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.