What is the Horizontal Accuracy of Nearmap 2D Imagery, and How is it Determined?
Our current generation camera system captures data with a ground sample distance (GSD) of 5.8cm (2.3”) in vertical imagery with a horizontal accuracy of 25.3cm (10”). Absolute horizontal accuracy is expressed as the root mean square of the radial distance error, also known as RMSERMSEr.
An earlier generation of our camera systems captured data with a GSD of 7.5cm (3”) vertical imagery with an absolute horizontal accuracy of 61.7cm (24.3”) RMSERMSEr.
Where we have historical captures taken with our current generation camera system, subsequent captures taken with our earlier generation camera system are improved to an absolute horizontal accuracy 38.7cm (15.2”) RMSERMSEr.
Nearmap also uses ground control points to verify our accuracy claims. Characteristics of our ground control points include good visibility, precise location, accurate location and open ground location. In essence, this means that the sample of ground points used are clearly identifiable in our aerial imagery without ambiguity, have a high accuracy of less than 2cm and are not subject to terrain distortions.