Uncertainty comparison of Digital Elevation Models derived from different image file formats

• Main Author: Spring, Ted
• Format: Others
• Language: English
• Published: Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad 2014
• Subjects: UAV; UAS; DEM; RAW format; Other Civil Engineering; Annan samhällsbyggnadsteknik
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17193

Unmanned Aerial Systems (UAS) have become increasingly popular recently for surveying and mapping because of their efficiency in acquiring remotely sensed data in a short amount of time and the low cost associated with them. They are used to generate digital elevation models (DEM) derived from aerial photography for various purposes such as the documentation of cultural heritage sites, archaeological surveying or earthwork volume calculations. This thesis investigates the possible effects different file formats may have on the quality of elevation models. In this thesis, an UAS survey was simulated using a digital camera to produce six DEMs based on JPEG, TIFF and RAW format in Agisoft Photoscan by taking two sets of images of a city model, in different light conditions. Furthermore, a reference DEM was produced in Geomagic Studio using data from a Leica Nova MS50 Multistation. The DEMs were then compared in Geomagic Control. The results from the 3D comparison in Geomagic Control show that the standard deviation of all elevation models is 4 mm with the exception of the elevation model derived from raw-edited images taken with lighting, which has a standard deviation of nearly 6 mm. Also, all of the models have an average deviation of 0.4 mm or less. The significant deviations in all DEMs occur in areas where the multistation lacked vision of certain objects of the city model such as walls, or on the edges of the analysed area. Additionally, the georeferencing results from Photoscan show that the DEMs based on normal light condition images have slightly lower georeferencing errors than the DEMs with lighting. It has been concluded that it is difficult to say whether file formats have any noticeably effect on the uncertainty of digital elevation models.