SEARCHING LOST PEOPLE WITH UAVS: THE SYSTEM AND RESULTS OF THE CLOSE-SEARCH PROJECT

This paper will introduce the goals, concept and results of the project named CLOSE-SEARCH, which stands for ’Accurate and safe EGNOS-SoL Navigation for UAV-based low-cost Search-And-Rescue (SAR) operations’. The main goal is to integrate a medium-size, helicopter-type Unmanned Aerial Vehicle (UAV), a thermal imaging sensor and an EGNOS-based multi-sensor navigation system, including an Autonomous Integrity Monitoring (AIM) capability, to support search operations in difficult-to-access areas and/or night operations. The focus of the paper is three-fold. Firstly, the operational and technical challenges of the proposed approach are discussed, such as ultra-safe multi-sensor navigation system, the use of combined thermal and optical vision (infrared plus visible) for person recognition and Beyond-Line-Of-Sight communications among others. Secondly, the implementation of the integrity concept for UAV platforms is discussed herein through the AIM approach. Based on the potential of the geodetic quality analysis and on the use of the European EGNOS system as a navigation performance starting point, AIM approaches integrity from the precision standpoint; that is, the derivation of Horizontal and Vertical Protection Levels (HPLs, VPLs) from a realistic precision estimation of the position parameters is performed and compared to predefined Alert Limits (ALs). Finally, some results from the project test campaigns are described to report on particular project achievements. Together with actual Search-and-Rescue teams, the system was operated in realistic, user-chosen test scenarios. In this context, and specially focusing on the EGNOS-based UAV navigation, the AIM capability and also the RGB/thermal imaging subsystem, a summary of the 1 INTRODUCTION The use of Unmanned Aerial Vehicles (UAVs) —more in gen- eral, Unmanned Aerial Systems (UASs)— for SAR operations is not new and has been traditionally fed by developments made in other fields. The main driver of UAV technology has been (and still is) the military field and this is because the nature of military developments is fairly overlapping SAR needs. As a example of that, we recall the UAVs used in the Iraq and Afghanistan wars were deployed to find people trapped in New Orleans buildings devastated by Hurricane Katrinas flood waters. Those platforms were equipped with thermal imaging systems to detect the body heat of storm survivors. A second example was the use of rotary- wing UAV platforms providing on-site imagery from the nuclear incident in Fukushima. More recently, a field that is increasingly putting effort on UAV development is Geomatics: the potential of those light-weight, easy-deployable platforms to quickly provide aerial and/or ground, good quality imagery is huge. A clear ex- ample of this interest raised within the geomatic community is the recent acquisition of Gateway, a provider of lightweight UAVs for photogrammetry and rapid terrain mapping applications, by Trimble. Indeed, the multi-application of the UAV potential to other fields, such as SAR, shall not be neglected. And even if [the lack of] regulations have been the stopper of the final jump to commercial applications, the willingness of regulators seems finally positive on pulling the trigger. As stated in the Institute of Navigation newsletter in winter 2011, ”the United States trans- portation secretary must develop a comprehensive plan to safely accelerate the integration of civil UAS into the national airspace system as soon as practicable, but not later than September 30th, 2015.” results is presented

Praktische Untersuchung zur Punktbestimmung mit Bilddaten digitaler Dreizeilenkameras

SIGLETIB: FR 4210 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

ANALYZING RCD30 OBLIQUE PERFORMANCE IN A PRODUCTION ENVIRONMENT

In 2014 the Institut Cartogràfic i Geològic de Catalunya (ICGC) decided to incorporate digital oblique imagery in its portfolio in response to the growing demand for this product. The reason can be attributed to its useful applications in a wide variety of fields and, most recently, to an increasing interest in 3d modeling. The selection phase for a digital oblique camera led to the purchase of the Leica RCD30 Oblique system, an 80MPixel multispectral medium-format camera which consists of one Nadir camera and four oblique viewing cameras acquiring images at an off-Nadir angle of 35º. The system also has a multi-directional motion compensation on-board system to deliver the highest image quality. The emergence of airborne oblique cameras has run in parallel to the inclusion of computer vision algorithms into the traditional photogrammetric workflows. Such algorithms rely on having multiple views of the same area of interest and take advantage of the image redundancy for automatic feature extraction. The multiview capability is highly fostered by the use of oblique systems which capture simultaneously different points of view for each camera shot. Different companies and NMAs have started pilot projects to assess the capabilities of the 3D mesh that can be obtained using correlation techniques. Beyond a software prototyping phase, and taking into account the currently immature state of several components of the oblique imagery workflow, the ICGC has focused on deploying a real production environment with special interest on matching the performance and quality of the existing production lines based on classical Nadir images. This paper introduces different test scenarios and layouts to analyze the impact of different variables on the geometric and radiometric performance. Different variables such as flight altitude, side and forward overlap and ground control point measurements and location have been considered for the evaluation of aerial triangulation and stereo plotting. Furthermore, two different flight configurations have been designed to measure the quality of the absolute radiometric calibration and the resolving power of the system. To quantify the effective resolution power of RCD30 Oblique images, a tool based on the computation of the Line Spread Function has been developed. The tool processes a region of interest that contains a single contour in order to extract a numerical measure of edge smoothness for a same flight session. The ICGC is highly devoted to derive information from satellite and airborne multispectral remote sensing imagery. A seamless Normalized Difference Vegetation Index (NDVI) retrieved from Digital Metric Camera (DMC) reflectance imagery is one of the products of ICGC’s portfolio. As an evolution of this well-defined product, this paper presents an evaluation of the absolute radiometric calibration of the RCD30 Oblique sensor. To assess the quality of the measure, the ICGC has developed a procedure based on simultaneous acquisition of RCD30 Oblique imagery and radiometric calibrated AISA (Airborne Hyperspectral Imaging System) imagery

PHOTOGRAMMETRIC PROCESSING USING ZY-3 SATELLITE IMAGERY

This paper evaluates the stereoscopic capacities of the Chinese sensor ZiYuan-3 (ZY-3) for the generation of photogrammetric products. The satellite was launched on January 9, 2012 and carries three high-resolution panchromatic cameras viewing in forward (22º), nadir (0º) and backward direction (-22º) and an infrared multi-spectral scanner (IRMSS), which is slightly looking forward (6º). The ground sampling distance (GSD) is 2.1m for the nadir image, 3.5m for the two oblique stereo images and 5.8m for the multispectral image. The evaluated ZY-3 imagery consists of a full set of threefold-stereo and a multi-spectral image covering an area of ca. 50km x 50km north-west of Barcelona, Spain. The complete photogrammetric processing chain was executed including image orientation, the generation of a digital surface model (DSM), radiometric image correction, pansharpening, orthoimage generation and digital stereo plotting. All 4 images are oriented by estimating affine transformation parameters between observed and nominal RPC (rational polynomial coefficients) image positions of 17 ground control points (GCP) and a subsequent calculation of refined RPC. From 10 independent check points RMS errors of 2.2m, 2.0m and 2.7m in X, Y and H are obtained. Subsequently, a DSM of 5m grid spacing is generated fully automatically. A comparison with the Lidar data results in an overall DSM accuracy of approximately 3m. In moderate and flat terrain higher accuracies in the order of 2.5m and better are achieved. In a next step orthoimages from the high resolution nadir image and the multispectral image are generated using the refined RPC geometry and the DSM. After radiometric corrections a fused high resolution colour orthoimage with 2.1m pixel size is created using an adaptive HSL method. The pansharpen process is performed after the individual geocorrection due to the different viewing angles between the two images. In a detailed analysis of the colour orthoimage artifacts are detected covering an area of 4691ha, corresponding to less than 2% of the imaged area. Most of the artifacts are caused by clouds (4614ha). A minor part (77ha) is affected by colour patch, stripping or blooming effects. For the final qualitative analysis on the usability of the ZY-3 imagery for stereo plotting purposes stereo combinations of the nadir and an oblique image are discarded, mainly due to the different pixel size, which produces difficulties in the stereoscopic vision and poor accuracy in positioning and measuring. With the two oblique images a level of detail equivalent to 1:25.000 scale is achieved for transport network, hydrography, vegetation and elements to model the terrain as break lines. For settlement, including buildings and other constructions a lower level of detail is achieved equivalent to 1:50.000 scale

Terrain modeling in an extremely steep mountain: A combination of airborne and terrestrial lidar, in

A combination of airborne and terrestrial LIDAR data has been used to model extremely steep mountains that are crossed by the Núria cog railway. This cog train is the only terrestrial transportation resort to reach the Núria Valley in the Spanish Pyrenees. The purpose of this Digital Elevations Model (DEM) is the modeling of rocks that fall over the railway track in order to implement protection measures to mitigate this risk. The airborne LIDAR system was an Optech ALTM 3025. Special parameter settings were selected to improve the coverage of the area but as the mountains contain many overhangs and vertical walls some occlusions appeared in the airborne LIDAR data. A terrestrial survey was also carried out in order to improve the terrain modeling. The terrestrial campaign consisted of 5 scenes observed with a Riegl LMS-Z210 mounted on a tripod in 5 static positions in front of the problematic vertical areas. Terrestrial laser scenes were oriented identifying previously surveyed reflectors. The poster presents the methodology applied to integrate data from both LIDAR sensors and shows the obtained results. 1