Cameras and Calibration
Camera choice and camera calibration are essential factors to understanding how to achieve high accuracy in your photogrammetry.
Accurate photogrammetry starts at the lens. If you intend to map a project and put every square centimetre in it’s right place, in XY&Z, you need to know the every pixel in every photo is it’s right place.
The Verity Positioning PPK Georeferencing System offers a simple, effective methodology to calibrate the camera.
Unlike high-end (expensive) aerial cameras, a typical camera in a UAV does not have the measurement quality characteristics of aerial cameras, it is “non-metric”, has lens distortions, is not calibrated and has moving parts that can affect calibration. Managing these errors with a simple calibration will put every pixel in it’s accurate position which translates to an accurate mapping product that can be used for measurement.
By capturing a couple of identifiable points on the ground, using the Georeferencing System on the UAV to do this, the actual focal length of the camera can be determined. These points can be anywhere on the project where they will be visible in a number of photos.
Our software will manage the calibration points, which can be imported into your photogrammetry software. Here they will be applied directly to correct the camera lens error. From that point on the whole project will be accurately surveyed.
Capturing a couple of calibration points on each project can be a standard operating procedure, or the calibration determined in one project can be used again in future projects, if the camera is found to hold a stable calibration.