Direct Photogrammetry Using Uav: Tests and First Results

Abstract

In recent years, the quality of high resolution acquisition platforms for geomatic applications has decidedly increased, especially in the performance of the sensors devoted to image acquisition.The small size of these new sensors combined with the increase in resolution allows them to be easily mounted onto Unmanned Aerial Vehicles (UAVs); in particular, calibrated, very-high-resolution digital cameras for photogrammetric purposes such as digital terrain model (DTM) and digital surface model (DSM) extraction, orthophotos, and map realization have been used. In this case, the UAV performance allows a high quality product to be obtained, considering the pixel size and the accuracy of the DTM/DSM which could be obtained with automatic procedures.Several navigation sensors (GPS/GNSS and IMU-MEMS) are embedded into UAVs in order to realize autonomous flight. The quality of these sensors, in terms of accuracy, depends on the model of UAV and its purpose. The navigation solution (position and attitude) is estimated by the internal UAV sensor and can be employed to directly georeference the images, in order to produce an quick and easy description and analysis of the overlooked area. This is a good condition for semi-automatic procedures using a bundle-block photogrammetric approach. But is it possible to realize a direct photogrammetry? And what are the limits?Several tests were carried out over different areas and in different conditions using three different UAVs belonging to the Geomatics group of the Politecnico di Torino.In this paper, an investigation of the limits of some commercial UAVs is reported, defining a dedicated procedure to valuate their performance, especially considering the use of UAVs for direct photogrammetry.

Brief Communication: The use of an unmanned aerial vehicle in a rockfall emergency scenario

“…In recent years, the use of unmanned aerial vehicles (UAVs) in operations relevant to civilian/commercial contexts is becoming increasingly common (Chiabrando et al, 2013). For example, an important application domain is in the area of emergency assistance and management, with scenarios including anthropic and/or natural disasters such as floods, earthquakes, and landslides (Tien-Yin et al, 2010).…”

“…Micro-UAVs are used to carry lightweight instruments, such as consumer digital cameras, to acquire photographs of the area of interest and eventually allow for photogrammetric processing (Neitzel et al, 2011). Moreover, micro-UAVs are also used as a test bed for the integration of multiple instruments, as well as for the development of new sensors (Colomina, 2007).…”

Automatic UAV Image Geo-Registration by Matching UAV Images to Georeferenced Image Data

“…Due to payload limitations, many commercial UAVs are usually equipped with lightweight sensors providing localization accuracies in the range of meters [12], which is not sufficient enough for photogrammetric applications using direct georeferencing. An investigation regarding the ability of direct georeferencing with UAV systems shows that the geolocalization accuracy of current UAV systems is still too low to perform direct applications of photogrammetry at very large scale [4].…”

“…However, accurate geo-registration of UAV imagery is still an open problem. Limited by on-board payload restrictions, UAVs are equipped with lightweight GNSS/IMU systems, whose georeferencing accuracies are in the range of meters [4] and far from the centimeter-level accuracy of airborne photogrammetry [5,6]. In order to achieve higher geo-registration accuracy beyond hardware limits, we use a pre-georeferenced aerial or satellite image as a reference and register the UAV image to the reference image with a novel feature-based image matching method.…”

Co-Registration of Multitemporal Uav Image Datasets for Monitoring Applications: A New Approach

“…Rapid developments in UAVs hardware and software technologies have made great impact in many geo-spatial application fields. Photogrammetry and remote sensing are some of the disciplines that have profited from the UAV technological advancement race (Everaerts, 2008;Eisenbeiß, 2009;Cook, 2011;Chiabrando et al, 2013). The latter has been driven by the need for relatively cheap and easy information acquisition and processing, which is the basic necessity for carrying out high quality research and development projects at minimum cost.…”