The sUAS Guide Issue 01, January 2016 | Page 32

1 - PROJECT DESCRIPTION
Our office has often wondered how accurate aerial surveys done by RPAS are. There are many reports been done by surveyors comparing datasets of orthomosaics and DEM to conventional survey methods. We have done so numerous times over both large and small datasets for validation to both ourselves and to other users. Nearly all reports have shown that there is very good correlation between conventional ground methods and RPAS photogrammetric surveys.
However, there seems to be a lack of information as to how accurate data derived from photogrammetric processes compares when excluding ground control and using only GPS location and IMU data from an autopilot. Many photogrammetry programs allow for flight logs that contain GPS tracks, IMU logs and camera trigger events to be included as a reference to determine the image centers giving a model a spatial dimension.
We recently undertook a comparison survey over a site to see the difference between final end products of a survey controlled only by a flight log and a survey corrected by addition of control points from ground survey.