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Behncke K.,University of Osnabruck | Ehlers M.,University of Osnabruck | Brinkhoff T.,Institute For Angewandte Photogrammetrie Und Geoinformatik
Kartographische Nachrichten | Year: 2012

Schlüsselbegriffe: Web Mapping, Web-Mapping-Anwendung, Web-Befragung There exists a lack of detailed empirical studies to assess the relevance of web mapping applications. This paper presents the result of an empirical study to analyze the importance of a web mapping application for a web portal. An exploratory focus is to evaluate how often geospatial information (in a broader information context) from this web portal is used and how important the web mapping applications are for the users of the web portal. Furthermore, it is evaluated which web mapping functions (e.g. routing, queries, printing) are of relevance to the users and what is their ranking. In addition to that a user based evaluation of the relevance of a mobile web mapping application is presented in this paper. Source


Bethmann F.,Institute For Angewandte Photogrammetrie Und Geoinformatik | Luhmann T.,Institute For Angewandte Photogrammetrie Und Geoinformatik
Photogrammetrie, Fernerkundung, Geoinformation | Year: 2011

Least-squares matching (LSM) for area-based image matching is a well known technique in photogrammetry and computer vision since more than two decades. Differences between two or more images can be modelled by estimating geometric and radiometric transformation functions within the functional model. Commonly the affine transformation is used as geometric transformation. Since this approach is not strict in terms of the projective imaging model, it is worthwhile to investigate alternative transformation models. Based on special close-range applications this paper presents an advanced least-squares matching algorithm that uses the projective transformation model and polynomial transformations to handle geometric distortions between the images. In the first part a detailed description of the functional model is given for both approaches. In the second part the results of different tests are presented. Lhe first test uses synthetic image data to investigate the 2D accuracy of the matching results (image coordinates). Within the second test a calibrated 3D reference body is used to investigate the 3D accuracy of point clouds that have been created with the PISA software for 3D free-form measurements by using the different matching approaches. All tests have shown that the polynomial transformation model yields to results with highest accuracy. Lhe affine and the projective model yield to distinct systematic deviations, especially for the non-plane surface of the 3D reference body. © 2011 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany. Source


Bannehr L.,Institute For Geoinformation Und Vermessung | Schmidt A.,Institute For Geoinformation Und Vermessung | Piechel J.,Institute For Angewandte Photogrammetrie Und Geoinformatik | Luhmann T.,Institute For Angewandte Photogrammetrie Und Geoinformatik
Photogrammetrie, Fernerkundung, Geoinformation | Year: 2013

This paper shows ho\ to use different' remote sen ing sensors and methods to obtain parameters about the urban built'-up areas. Withi n the cooperative research project Hi ReSens a hyperspectral scanner, an airborne laser scanner, a thermal camera, and a RGB-camera were employed on a small aircraft to determine roof material and geomet'ric paramet'ers as well a heat' bridges withlll t'he city of Oldenburg, Lower Saxony, Germany, HiReSens aims to combine various geometrical highly resolved data (50 cm) in order to survey the state of the roof areas Thermal data were used to obtain the temperature distribution of single roof tops. The hyperspectral data provide information on the roofing materials, Support vector machines ( VM) were used to c1assi( the e roof material.. Five out of six roofing material were clearly detected. From airborne laser scanning (ALS) data a digital surface model and a digital terrain model were calculated, These models in combination with hyperspectral data form the basis to locate the buildings with the be t orientations for solar panel. A decision tree algorithm give sati factory results in this case. The combination of the different data ets offers the opportunity to use synergies between different sensor systems. The central goals were the development of tools for the detection of thermal bridges by means of thermal data, pectral differentiation of roof parameters on the ba is of hyperspectral data as well as 3D-capture of building from ALS data. © 2013 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany. Source


Luhmann T.,Institute For Angewandte Photogrammetrie Und Geoinformatik | Ohm J.,Institute For Angewandte Photogrammetrie Und Geoinformatik | Piechel J.,Institute For Angewandte Photogrammetrie Und Geoinformatik | Roelfs T.,Institute For Angewandte Photogrammetrie Und Geoinformatik
Photogrammetrie, Fernerkundung, Geoinformation | Year: 2011

Geometric Calibration of Thermal Cameras. This paper discusses strategies, tools and methods for the geometric calibration of close-range thermal cameras as they are widely used for building monitoring and material testing. Two different testfields have been developed and tested whereby each of them provides target points in the thermal spectrum. Four different cameras with solid-state imaging sensors have been calibrated. In general, all lenses show relatively large distortions due to decentering of lenses and non-orthogonality of the image coordinate system. Using a 2D testfield with burning lamps an accuracy of 0.3 pixels can be achieved while a 3D testfield with reflective circular targets provides residuals in the order of 0.05 pixels. This leads to geometrically improved thermal images that can be used to achieve higher quality for various applications, such as mosaicking, 3D-texturing or pan sharpening. © 2011 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany. Source

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