ABSTRACT:Since a few years, micro UAS (unmanned aerial systems) with vertical take off and landing capabilities like quadro-or octocopter are used as sensor platform for Aerophotogrammetry. Since the restricted payload of micro UAS with a total weight up of 5 kg (payload only up to 1.5 kg), these systems are often equipped with small format cameras. These cameras can be classified as amateur cameras and it is often the case, that these systems do not meet the requirements of a geometric stable camera for photogrammetric measurement purposes. However, once equipped with a suitable camera system, an UAS is an interesting alternative to expensive manned flights for small areas. The operating flight height of the above described UAS is about 50 up to 150 meters above ground level. This low flight height lead on the one hand to a very high spatial resolution of the aerial imagery. Depending on the cameras focal length and the sensor's pixel size, the ground sampling distance (GSD) is usually about 1 up to 5 cm. This high resolution is useful especially for the automatic generation of homologous tie-points, which are a precondition for the image alignment (bundle block adjustment). On the other hand, the image scale depends on the object's height and the UAV operating height. Objects like mine heaps or construction sites show high variations of the object's height. As a result, operating the UAS with a constant flying height will lead to high variations in the image scale. For some processing approaches this will lead to problems e.g. the automatic tie-point generation in stereo image pairs. As precondition to all DEM generating approaches, first of all a geometric stable camera, sharp images are essentially. Well known calibration parameters are necessary for the bundle adjustment, to control the exterior orientations. It can be shown, that a simultaneous on site camera calibration may lead to misaligned aerial images. Also, the success rate of an automatic tie-point generation differs extremely between several photogrammetric software packages. In this article, the calibration results of a suitable camera system will be shown. For a small format consumer grade camera, the authors will give the proof of ability for photogrammetric measurements purposes. This includes the results of different processing approaches for DEM generation of environments showing high object height variations.
ABSTRACT:This article describes a specific image quality problem using an UAV and the commercially available multispectral camera Tetracam ADC Lite. The tests were carried out with commercially available UAV Multirotor MR-X 8 performed under normal use and conditions. The ADC Lite shows a remarkable rolling shutter effect caused by the movement and vibrations of the UAV and a slow readout speed of the sensor.Based on these studies the current state of a sensor development is presented, which is composed of two compact cameras with Foveon sensors. These cameras allow to record high quality image data without motion blur or rolling shutter effect. One camera captures the normal colour range; the second camera is modified for the near infrared.The moving parts of both cameras are glued to ensure that a geometric camera calibration is valid over a longer period of time. The success of the gluing procedure has been proven by multiple calibrations. For the matching of the colour-and infrared image the usability of calibrated relative orientation parameters between both cameras were tested. Despite absolutely synchronous triggering of the cameras by an electrical signal, a time delay can be found up to 3/100 s between the images. This time delay in combination with the movement and rotation of the UAV while taking the photos results in a significant error in the previously calibrated relative orientation. These parameters should not be used in further processing.This article concludes with a first result of a 4-channel image and an outlook on the following investigations.
ABSTRACT:Land cover information is essential for urban planning and for land cover change monitoring. This paper presents an overview of the work conducted at the Federal Agency for Cartography and Geodesy (BKG) with respect to Synthetic Aperture Radar (SAR) based land cover classification. Two land cover classification approaches using SAR images are reported in this paper. The first method involves a rule-based classification using only SAR backscatter intensity while the other method involves supervised classification of a polarimetric composite of the same SAR image. The LBM-DE has been used for training and validation of the SAR classification results. Images acquired from the Sentinel-1a satellite are used for classification and the results have been reported and discussed. The availability of Sentinel-1a images that are weather and daylight independent allows for the creation of a land cover classification system that can be updated and validated periodically, and hence, be used to assist other land cover classification systems that use optical data. With the availability of Sentinel-2 data, land cover classification combining Sentinel-1a and Sentinel-2 images present a path for the future.
ABSTRACT:Copernicus is an European system created for Earth observation and monitoring. It consists of a set of Earth observation satellites and in-situ sensors that provide geo-information that are used, through a set of Copernicus services, for applications related to the environment and global security. The main services of the Copernicus programme address six thematic areas: land, marine, atmosphere, climate change, emergency management and security. In Germany, there is a national service team of Copernicus service coordinators, who are responsible for the national development of the Copernicus services and for providing user-specific information about the Copernicus processes. These coordinators represent the contact points for all the programmes and services concerning their respective Copernicus theme. To publish information about Copernicus, national conferences and workshops are organised. Many people are involved in planning the continuous process of bringing the information to public authorities, research institutes and commercial companies. The Federal Agency for Cartography and Geodesy (Bundesamt für Kartographie und Geodäsie, BKG) is one such organisation, and is mainly responsible for the national land monitoring service of Copernicus. To make use of the freely available data from the Copernicus programme, the Federal Agency for Cartography and Geodesy is currently developing new applications and projects in the field of remote sensing and land monitoring. These projects can be used by other public authorities as examples on how to use the Copernicus data and services for their individual demands and requirements. Copernicus data and services are currently not very commonly used in the daily routine of the national mapping agencies, but they will soon be.
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