Nowadays several scientific disciplines utilize Citizen Science (CitSci) as a research approach. Natural hazard research and disaster management also benefit from CitSci since people can provide geodata and the relevant attributes using their mobile devices easily and rapidly during or after an event. An earthquake, depending on its intensity, is among the highly destructive natural hazards. Coordination efforts after a severe earthquake event are vital to minimize its harmful effects and timely in-situ data are crucial for this purpose. The aim of this study is to perform a CitSci pilot study to demonstrate the usability of data obtained by volunteers (citizens) for creating earthquake iso-intensity maps in a short time. The data were collected after a 5.8 Mw Istanbul earthquake which occurred on 26 September 2019. Through the mobile app “I felt the quake”, citizen observations regarding the earthquake intensity were collected from various locations. The intensity values in the app represent a revised form of the Mercalli intensity scale. The iso-intensity map was generated using a spatial kriging algorithm and compared with the one produced by The Disaster and Emergency Management Presidency (AFAD), Turkey, empirically. The results show that collecting the intensity information via trained users is a plausible method for producing such maps.
Cal/Val activities within the Earthnet Data Assessment Pilot (EDAP) Project of the European Space Agency (ESA) cover several Earth Observation (EO) satellite sensors, including Third-Party Missions (TPMs). As part of the validation studies of very-high-resolution (VHR) sensor data, the geometric and radiometric quality of the images and the mission compliance of the SkySat satellites owned by Planet were evaluated in this study. The SkySat constellation provides optical images with a nominal spatial resolution of 50 cm, and has the capacity for multiple visits of any place on Earth each day. The evaluations performed over several test sites for the purpose of the EDAP Maturity Matrix generation show that the high resolution requirement is fulfilled with high geometric accuracy, although various systematic and random errors could be observed. The 2D and 3D information extracted from SkySat data conform to the quality expectations for the given resolution, although improvements to the vendor-provided rational polynomial coefficients (RPCs) are essential. The results show that the SkySat constellation is compliant with the specifications and the accuracy results are within the ranges claimed by the vendor. The signal-to-noise ratio assessments revealed that the quality is high, but variations occur between the different sensors.
Abstract. The requirement for very high-resolution satellite imagery by different applications has been increasing continuously. Several commercial and government-supported missions provide sub-meter spatial resolutions from optical sensors aboard Earth Observation (EO) satellites. The MAXAR satellite constellation acquires images with up to 30 cm Ground Sampling Distances (GSDs); and the High-Definition (HD) image production technology developed by MAXAR doubles the resolution by using artificial intelligence methods. Although the spatial resolution is one of the most important image quality metrics, several other factors indicated by diverse radiometric and geometric characteristics may circumscribe the usability of data in different projects. As part of mandatory activities of European Space Agency (ESA), Earthnet Programme provides a framework for integrating Third-Party Missions into the overall EO strategy and promotes the international use of the data. The Earthnet Data Assessment Pilot (EDAP) project aims at assessing the quality and the suitability of TPMs, and provides a communication platform between mission providers to ensure the coherence of the systems. In this study, the radiometric quality of the MAXAR HD products was evaluated within the EDAP project framework by using several General Image-Quality Equation (GIQE) metrics, visual inspections, and comparative assessments with orthophotos obtained from an Unmanned Aerial Vehicle (UAV) platform and with the original (non-HD) orthophotos with 30 cm resolutions. The results show that the spatial resolution improvements are observable in urban areas, where sharp edges are present. However, blurring and color noise patterns also occured in the HD images.
Coğrafi Bilgi Sistemlerinin (CBS) teknolojik gelişmeler doğrultusunda kullanımı giderek artmaktadır. Gelişen teknolojik sistemler CBS'nin, sadece masaüstü bilgisayarlar üzerinden değil, aynı zamanda web ve mobil platformlar üzerinde de etkin olarak kullanıldığını göstermektedir. CBS ile kullanıcıların entegre olmasını sağlayan mobil uygulamalar, kullanıcıların sisteme hızlı erişmesini sağlayarak CBS'ye dinamizm katmaktadır. Bu dinamik yapıyı sağlayacak şekilde oluşturulan CBS'ler, kullanıcılardan gelen verileri depolayarak değerlendirebilmektedir. Böylelikle CBS, altlık verinin yanında uygulamanın kullanımına bağlı olarak devamlı bir şekilde güncellenen kullanıcı verilerine de sahip olmaktadır. Kullanıcılar ile CBS arasında bu veri iletişimini sağlamak için internet ortamından faydalanılmaktadır. Bu sistemlerin oluşturulabilmesi için gerekli olan teknolojik altyapıları lisanslama açısından ticari ve açık kaynaklı olmak üzere ikiye ayırmak mümkündür. Açık kaynaklı yazılımlar ile geliştirilen bu çalışmada kullanıcılar tarafından gelen verilerin de depolandığı bir web tabanlı CBS oluşturulmuştur. Sistemin mobil uygulama kısmında Android işletim sistemi, veri tabanı olarak PostgreSQL, harita sunucusu olarak ise MapServer yazılımı kullanılmıştır. Geliştirilen "Sarsıntıyı Hissettim" uygulaması ile kullanıcılar tarafından sarsıntı şiddeti verileri depolanarak bu verilerin harita sunucusu üzerinden görüntülenmesi sağlanmıştır. Ayrıca bu sistem ile bir sivil bilim uygulaması geliştirilerek, sarsıntı hissinin derecelendirilmesi amaçlanmıştır.
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