Proposition of a methodology for producing orthophotos from Google Earth free browser images


Abstract in English

Orthorectification is the process of geometrically correcting imagery for geometric distortions which can be caused by topography, camera geometry, and sensor related errors. The output of orthorectification has the same geometric characteristics of a traditional map. But getting areal or satellite images is an expensive process requiring complex administrative procedures . In this study we propose take advantage of free images available in the browser Google Earth in order to produce an orthophoto. Then we will assess the horizontal accuracy of the resulted orthophoto to know the limitations of its use engineering applications such as maps production and updating. The proposed methodology is based on the flight simulation process within Google Earth to acquire a stereoscopic pair of overlapping images. After that, this pair will be oriented using control points. The oriented pair is then used to generate a Digital Terrain Model (DTM) and to generate the orthophoto. Later, we will examine the accuracy of this orthophoto by comparing it with a topographic plane (scale 1/1000) and with a rectified satellite image of the same area.

References used

Hinton, J. C. (1996). GIS and remote sensing integration for environmental applications. International Journal of Geographical Information Systems, 10, 877–890
Kaczynski, R., Donnay, J-P. & Muller, F., (1995). Satellite image maps of Warsaw in the scale 1:25,000. Topography from space, EARSeL Advances in Remote Sensing, 4(2), 100-103
Nielsen, M.O. (2004). True orthophoto generation. Master thesis. Technical University in Denmark

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