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Positional accuracy evaluation of Google Earth in Addis Ababa, Ethiopia

Mulu Yalemzewd Abere, Derib Sisay Demeku

Artificial Satellites : Journal of Planetary Geodesy

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2019

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Vol. 54, No. 2

43--56

EN

From the time when it was first launched in 2005, satellite data generated from Google Earth are freely available online. Hence, without being conducting concrete studies about the accuracy of satellite data from Google Earth, Google Earth are chiefly used for different field of studies in different sectors for different purposes in Ethiopia. In this regard, it was planned to conduct this study by establishing the main objective to evaluate the positional accuracy of Google Earth. Hence, in order to address the aforementioned objective, a brief methodology for collecting and analyzing data was performed. The positional accuracy of Google Earth for both horizontal and vertical cases was evaluated. The acquired horizontal RMSE of Google Earth was found fit to produce a class-1 map of having 1:20,000 scale as recommended by ASPRS-1990. Unlike for horizontal case, the computed RMSE for vertical positional accuracy of Google Earth was not found fit for preparing class-1 map. However, making correlations between field survey and GE can provide 95% fitness, and also, subtracting the acquired RMSE for the vertical case from the original Google Earth elevation data can provide a 90% fitness for preparing class-1 map as well.

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Prawne, techniczne i społeczne aspekty pomiarów fotogrametrycznych

Pyka K.

Przegląd Geodezyjny

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2016

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R. 88, nr 11

8--12

PL

Tematem artykułu jest analiza czynników, które kształtują wykorzystanie fotogrametrii lotniczej jako jednej z geodezyjnych technik pomiarowych. Jest zapotrzebowanie na efektywną metodę aktualizacji ewidencji gruntów i budynków w szczególności na terenach wiejskich. Jak pokazano w artykule regulacje prawne dopuszczają stosowanie fotogrametrii dla potrzeb EGiB. Niestety dość powszechna jest opinia, wywodząca się z przeszłości, o zbyt niskiej dokładności fotogrametrii. W artykule zawarta jest polemika z tym poglądem, przedstawione są argumenty przemawiające za spełnieniem przez fotogrametrię kryteriów dokładnościowych. Natomiast jako istotniejszy wskazuje się problem niekompletności pomiaru fotogrametryczego zarówno w zakresie granic działek jak i budynków. Jako remedium na zwiększenie kompletności pomiaru budynków przedstawiono 2-etapową metodę łączącą fotogrametrię i pomiar terenowy. W konkluzji stwierdzono, że istnieją przesłanki do zwiększenia znaczenia fotogrametrii wśród metod pomiarowych, zwłaszcza w dużych projektach na terenach wiejskich.

EN

The topic of the article is the analysis of factors, which are formed the usage of aerial photogrammetry as one of surveying techniques. There is at present a high demand for rapid and cost effective method of update of cadastral maps in rural areas. As was showed in the paper the legal regulations allow the application of photogrammetry in cadaster. Unfortunately, very popular is an opinion, which is based on experience from the past, that the accuracy of photogrammetry for land surveying is not sufficient. The paper presents many arguments that the accuracy of modern, digital photogrammetry fulfills the accuracy requirements. The article indicated that the matter of applicability of photogrammetry for cadaster is too low completeness of measurements of parcel boundaries and buildings footprints. As a remedy for incompleteness of buildings measurements the paper presents a two-stage surveying method, which combines aerial photogrammetry and terrestrial measuring. Finally, it was stated that there is a perspective of granting the photogrammetry the rank of the surveying method, especially in large projects in rural areas.

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Positional accuracy assessment of googleearth in Riyadh

Farah A., Algarni D.

Artificial Satellites : Journal of Planetary Geodesy

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2014

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Vol. 49, No. 2

101--106

EN

Google Earth is a virtual globe, map and geographical information program that is controlled by Google corporation. It maps the Earth by the superimposition of images obtained from satellite imagery, aerial photography and GIS 3D globe. With millions of users all around the globe, GoogleEarth® has become the ultimate source of spatial data and information for private and public decision-support systems besides many types and forms of social interactions. Many users mostly in developing countries are also using it for surveying applications, the matter that raises questions about the positional accuracy of the Google Earth program. This research presents a small-scale assessment study of the positional accuracy of GoogleEarth® Imagery in Riyadh; capital of Kingdom of Saudi Arabia (KSA). The results show that the RMSE of the GoogleEarth imagery is 2.18 m and 1.51 m for the horizontal and height coordinates respectively.