371 research outputs found
Earth observation for sustainable urban planning in developing countries: needs, trends, and future directions
Abstract: Cities are constantly changing and authorities face immense challenges in obtaining accurate and timely data to effectively manage urban areas. This is particularly problematic in the developing world where municipal records are often unavailable or not updated. Spaceborne earth observation (EO) has great potential for providing up-to-date spatial information about urban areas. This article reviews the application of EO for supporting urban planning. In particular, the article overviews case studies where EO was used to derive products and indicators required by urban planners. The review concludes that EO has sufficiently matured in recent years but that a shift from the current focus on purely science-driven EO applications to the provision of useful information for day-to-day decision-making and urban sustainability monitoring is clearly needed
Quantifying the physical composition of urban morphology throughout Wales based on the time series (1989-2011) analysis of Landsat TM/ETM+ images and supporting GIS data
Knowledge of impervious surface areas (ISA) and on their changes in magnitude, location, geometry and morphology over time is significant for a range of practical applications and research alike from local to global scales. Despite this, use of Earth Observation (EO) technology in mapping ISAs within some European Union (EU) countries, such as the United Kingdom (UK), is to some extent scarce. In the present study, a combination of methods is proposed for mapping ISA based on freely distributed EO imagery from Landsat TM/ETM+ sensors. The proposed technique combines a traditional classifier and a linear spectral mixture analysis (LSMA) with a series of Landsat TM/ETM+ images to extract ISA. Selected sites located in Wales, UK, are used for demonstrating the capability of the proposed method. The Welsh study areas provided a unique setting in detecting largely dispersed urban morphology within an urban-rural frontier context. In addition, an innovative method for detecting clouds and cloud shadow layers for the full area estimation of ISA is also presented herein. The removal and replacement of clouds and cloud shadows, with underlying materials is further explained. Aerial photography with a spatial resolution of 0.4 m, acquired over the summer period in 2005 was used for validation purposes. Validation of the derived products indicated an overall ISA detection accuracy in the order of ~97%. The latter was considered as very satisfactory and at least comparative, if not somehow better, to existing ISA products provided on a national level. The hybrid method for ISA extraction proposed here is important on a local scale in terms of moving forward into a biennial program for the Welsh Government. It offers a much less subjectively static and more objectively dynamic estimation of ISA cover in comparison to existing operational products already available, improving the current estimations of international urbanization and soil sealing. Findings of our study provide important assistance towards the development of relevant EO-based products not only inaugurate to Wales alone, but potentially allowing a cost-effective and consistent long term monitoring of ISA at different scales based on EO technology
Automatic Pole Detection in Aerial and Satellite Imagery for precise Image Registration with SAR Ground Control Points
The world-wide absolute geographic positioning accuracy of optical Satellite imagery is mostly about a few pixels of the image resolution. So for example WorldView-3 images have a CE90 of about 4 m. Also the direct georeferencing without ground control information of aerial imagery is in the same range of one to a few metres. These inaccuracies originate predominantly in uncertainties of angular measurements for the sensor attitude. An angular error of only one arc-second at a satellite 750 km above ground results in an absolute error on ground of 3.6 metres. On the other hand radar satellites like TerraSAR-X or TanDEM-X do not measure angles but signal runtimes. So if we identify the same point in an optical image and in a radar image we can solve the problem of inaccurate angle-measurements in the optical sensor models and are able to georeference optical images world wide absolute to below one pixel. In this paper we present a method for identification of point-objects which can be detected in both types of images: the footpoints of poles. If such a footpoint of a pole can be detected simultaneously in both types of images the geoposition of the optical image can be corrected to the accuracy of the point-measurement in the radar image. To achieve a high accuracy also a nearly perfect correction of all errors in signal propagation times of the radar signals has to be conducted. In this paper we describe how the footpoints of poles will be extracted in optical spaceborne or air-borne imagery and how these footpoints are correlated to the potential footpoints of poles detected in the radar imagery
AutomatizovanĂ© odvozenĂ geometrie jĂzdnĂch pruhĹŻ na základÄ› leteckĂ˝ch snĂmkĹŻ a existujĂcĂch prostorovĂ˝ch dat
The aim of the thesis is to develop a method to identify driving lanes based on aerial images and existing spatial data. The proposed method uses up to date available data in which it identifies road surface marking (RSM). Polygons classified as RSM are further processed to obtain their vector line representation as the first partial result. While processing RSM vectors further, borders of driving lanes are modelled as the second partial result. Furthermore, attempts were done to be able to automatically distinguish between solid and broken lines for a higher amount of information contained in the resulting dataset. Proposed algorithms were tested in 20 case study areas and results are presented further in this thesis. The overall correctness as well as the positional accuracy proves effectivity of the method. However, several shortcomings were identified and are discussed as well as possible solutions for them are suggested. The text is accompanied by more than 70 figures to offer a clear perspective on the topic. The thesis is organised as follows: First, Introduction and Literature review are presented including the problem background, author's motivation, state of the art and contribution of the thesis. Secondly, technical and legal requirements of RSM are presented as well as theoretical concepts and...CĂlem tĂ©to práce je vytvoĹ™enĂ metody odvozenĂ geometrie jĂzdnĂch pruhĹŻ na základÄ› leteckĂ˝ch snĂmkĹŻ a existujĂcĂch prostorovĂ˝ch dat. NavrĹľená metoda pouĹľĂvá souÄŤasnÄ› dostupná data, ve kterĂ˝ch identifikuje vodorovnĂ© dopravnĂ znaÄŤenĂ (VDZ). Polygony, kterĂ© jsou klasifikovány jako VDZ, jsou následnÄ› zpracovány jednĂm z navrĹľenĂ˝ch algoritmĹŻ, kterĂ˝ vytvořà jejich liniovou reprezentaci (vektor), která je jednĂm z dĂlÄŤĂch vĂ˝sledkĹŻ. Tyto linie jsou dále analyzovány a na jejich základÄ› docházĂ k vytvoĹ™enĂ liniĂ symbolizujĂcĂch hranice mezi jednotlivĂ˝mi jĂzdnĂmi pruhy, kterĂ© pĹ™edstavujĂ druhĂ˝ dĂlÄŤĂ vĂ˝sledek. KromÄ› toho je snaha o automatizovanĂ© rozlišenĂ mezi plnou a pĹ™erušovanou čárou, coĹľ pĹ™inášà vÄ›tšà informaÄŤnĂ hodnotu vytvoĹ™enĂ©ho datovĂ©ho souboru. NavrhnutĂ© algoritmy byly otestovány ve 20 zájmovĂ˝ch ĂşzemĂch a vĂ˝sledky testovánĂ jsou uvedeny v tĂ©to práci. Celková správnost a stejnÄ› tak i prostorová pĹ™esnost testovanĂ˝ch dat dokazuje, Ĺľe navrhovaná metoda je efektivnĂ. V prĹŻbÄ›hu testovánĂ byly identifikovány urÄŤitĂ© nedostatky navrhovanĂ©ho procesu, kterĂ© jsou v textu blĂĹľe popsány, stejnÄ› tak je v textu navrĹľeno jejich eventuálnĂ Ĺ™ešenĂ. Práce je doprovázena vĂce neĹľ 70 obrázky, kterĂ© ilustrujĂ text a pĹ™inášejĂ jasnÄ›jšà pohled na probĂraná tĂ©mata. Práce je rozdÄ›lena na následujĂcĂ kapitoly: nejprve Ăšvod a PĹ™ehled...Department of Applied Geoinformatics and CartographyKatedra aplikovanĂ© geoinformatiky a kartografiePĹ™ĂrodovÄ›decká fakultaFaculty of Scienc
AutomatizovanĂ© odvozenĂ geometrie jĂzdnĂch pruhĹŻ na základÄ› leteckĂ˝ch snĂmkĹŻ a existujĂcĂch prostorovĂ˝ch dat
The aim of the thesis is to develop a method to identify driving lanes based on aerial images and existing spatial data. The proposed method uses up to date available data in which it identifies road surface marking (RSM). Polygons classified as RSM are further processed to obtain their vector line representation as the first partial result. While processing RSM vectors further, borders of driving lanes are modelled as the second partial result. Furthermore, attempts were done to be able to automatically distinguish between solid and broken lines for a higher amount of information contained in the resulting dataset. Proposed algorithms were tested in 20 case study areas and results are presented further in this thesis. The overall correctness as well as the positional accuracy proves effectivity of the method. However, several shortcomings were identified and are discussed as well as possible solutions for them are suggested. The text is accompanied by more than 70 figures to offer a clear perspective on the topic. The thesis is organised as follows: First, Introduction and Literature review are presented including the problem background, author's motivation, state of the art and contribution of the thesis. Secondly, technical and legal requirements of RSM are presented as well as theoretical concepts and...CĂlem tĂ©to práce je vytvoĹ™enĂ metody odvozenĂ geometrie jĂzdnĂch pruhĹŻ na základÄ› leteckĂ˝ch snĂmkĹŻ a existujĂcĂch prostorovĂ˝ch dat. NavrĹľená metoda pouĹľĂvá souÄŤasnÄ› dostupná data, ve kterĂ˝ch identifikuje vodorovnĂ© dopravnĂ znaÄŤenĂ (VDZ). Polygony, kterĂ© jsou klasifikovány jako VDZ, jsou následnÄ› zpracovány jednĂm z navrĹľenĂ˝ch algoritmĹŻ, kterĂ˝ vytvořà jejich liniovou reprezentaci (vektor), která je jednĂm z dĂlÄŤĂch vĂ˝sledkĹŻ. Tyto linie jsou dále analyzovány a na jejich základÄ› docházĂ k vytvoĹ™enĂ liniĂ symbolizujĂcĂch hranice mezi jednotlivĂ˝mi jĂzdnĂmi pruhy, kterĂ© pĹ™edstavujĂ druhĂ˝ dĂlÄŤĂ vĂ˝sledek. KromÄ› toho je snaha o automatizovanĂ© rozlišenĂ mezi plnou a pĹ™erušovanou čárou, coĹľ pĹ™inášà vÄ›tšà informaÄŤnĂ hodnotu vytvoĹ™enĂ©ho datovĂ©ho souboru. NavrhnutĂ© algoritmy byly otestovány ve 20 zájmovĂ˝ch ĂşzemĂch a vĂ˝sledky testovánĂ jsou uvedeny v tĂ©to práci. Celková správnost a stejnÄ› tak i prostorová pĹ™esnost testovanĂ˝ch dat dokazuje, Ĺľe navrhovaná metoda je efektivnĂ. V prĹŻbÄ›hu testovánĂ byly identifikovány urÄŤitĂ© nedostatky navrhovanĂ©ho procesu, kterĂ© jsou v textu blĂĹľe popsány, stejnÄ› tak je v textu navrĹľeno jejich eventuálnĂ Ĺ™ešenĂ. Práce je doprovázena vĂce neĹľ 70 obrázky, kterĂ© ilustrujĂ text a pĹ™inášejĂ jasnÄ›jšà pohled na probĂraná tĂ©mata. Práce je rozdÄ›lena na následujĂcĂ kapitoly: nejprve Ăšvod a PĹ™ehled...Department of Applied Geoinformatics and CartographyKatedra aplikovanĂ© geoinformatiky a kartografiePĹ™ĂrodovÄ›decká fakultaFaculty of Scienc
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