UAV-based photogrammetry: monitoring of a building zone
The use of small-size unmanned aerial vehicles (UAV) for civil applications in many different fields such as archaeology, disaster monitoring, aerial surveying or mapping has significantly increased in recent years. The high flexibility and the low cost per acquired information compared to classical systems – terrestrial or aerial – offer a high variety of different applications. This paper addresses the photogrammetric analysis of a monitoring project and gives an insight into the potential of UAV using low cost sensors and present-day processing software. The area of interest is the "zero:e-park", a building zone of zero emission housing in Hannover, Germany, that we monitored in three different epochs over a period of five months. We show that we can derive three dimensional information with an accuracy of a few centimetres. Changes during the epochs, also small ones like the dismantling of scaffolding can be detected. We also depict the limitations of the DEM generation approach which occur at sharp edges and height jumps as well as repetitive structure. Additionally, we compare two different commercial software packages which reveals that some systematic errors still remain in the results.