69 research outputs found

    RAT: A Referencing and Annotation Tool for Digitized Early Maps

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    RAT is designed to support users in identifying place markers in digitised early maps and to link these place markers to modern maps. RAT facilitates a geo-referencing by suggesting the most likely modern places based on an estimated mapping and a phonetic search for place names

    RAT 2.0

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    Automation aspects for the georeferencing of photogrammetric aerial image archives in forested scenes

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    Photogrammetric aerial film image archives are scanned into digital form in many countries. These data sets offer an interesting source of information for scientists from different disciplines. The objective of this investigation was to contribute to the automation of a generation of 3D environmental model time series when using small-scale airborne image archives, especially in forested scenes. Furthermore, we investigated the usability of dense digital surface models (DSMs) generated using these data sets as well as the uncertainty propagation of the DSMs. A key element in the automation is georeferencing. It is obvious that for images captured years apart, it is essential to find ground reference locations that have changed as little as possible. We studied a 68-year-long aerial image time series in a Finnish Karelian forestland. The quality of candidate ground locations was evaluated by comparing digital DSMs created from the images to an airborne laser scanning (ALS)-originated reference DSM. The quality statistics of DSMs were consistent with the expectations; the estimated median root mean squared error for height varied between 0.3 and 2 m, indicating a photogrammetric modelling error of 0.1 parts per thousand with respect to flying height for data sets collected since the 1980s, and 0.2 parts per thousand for older data sets. The results show that of the studied land cover classes, "peatland without trees" changed the least over time and is one of the most promising candidates to serve as a location for automatic ground control measurement. Our results also highlight some potential challenges in the process as well as possible solutions. Our results indicate that using modern photogrammetric techniques, it is possible to reconstruct 3D environmental model time series using photogrammetric image archives in a highly automated way.Peer reviewe

    Geomatics Applications to Contemporary Social and Environmental Problems in Mexico

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    Trends in geospatial technologies have led to the development of new powerful analysis and representation techniques that involve processing of massive datasets, some unstructured, some acquired from ubiquitous sources, and some others from remotely located sensors of different kinds, all of which complement the structured information produced on a regular basis by governmental and international agencies. In this chapter, we provide both an extensive revision of such techniques and an insight of the applications of some of these techniques in various study cases in Mexico for various scales of analysis: from regional migration flows of highly qualified people at the country level and the spatio-temporal analysis of unstructured information in geotagged tweets for sentiment assessment, to more local applications of participatory cartography for policy definitions jointly between local authorities and citizens, and an automated method for three dimensional (3D) modelling and visualisation of forest inventorying with laser scanner technology

    Aktives Lernen für Informationsextraktion aus historischen Karten

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    Es gibt viele praktische Probleme im GIS, die derzeit nicht automatisch gelöst werden können, nicht weil unsere Algorithmen zu langsam sind, sondern weil wir überhaupt keinen zufriedenstellenden Algorithmus haben. Dies kann vorkommen, wenn es um Semantik geht, z. B. beim Extrahieren von Informationen oder beim Entwerfen von Visualisierungen. Von einem Computer kann derzeit nicht erwartet werden, dass er solche Probleme völlig unbeaufsichtigt löst. Darum betrachten wir den menschlichen Einsatz explizit als Ressource. Ein Algorithmus soll so viel Arbeit wie möglich in hoher Qualität leisten – aber entscheidend ist auch, dass er intelligent genug ist, um zu sehen, wo er Hilfe braucht, was er den Benutzer fragen sollte und wie er dessen Antworten berücksichtigt. Dieses Konzept bezieht sich auf neue Bereiche der Informatik wie aktives Lernen, aber wir legen den Fokus auf das richtige Design und die Analyse von Algorithmen und den daraus resultierenden Dialog zwischen Algorithmus und Mensch, den wir algorithmisch geführte Benutzerinteraktion nennen. Dieser Ansatz soll auf die Informationsextraktion aus historischen Karten angewandt werden

    Applications of Photogrammetry for Environmental Research

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    ISPRS International Journal of Geo-Information: special issue entitled "Applications of Photogrammetry for Environmental Research
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