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Significance of Photogrammetry in 3D Visualization and Building Reconstruction
 Usman Khan GIS Postgraduate Researcher School of Geography & Environmental Science Monash University, AUSTRALIA Email: ukha1@student.monash.edu.au
Background
This abstract expands upon the proposal from Ghardirian & Bishop (2002) whereby maps are often termed as models of reality. For many years, cartographers had to face the difficulties of showing three dimensional (X, Y, Z) realities on a flat (X, Y) surface of a map. The concept can be explored in a variety of ways. Firstly, there is a third dimension (height) that varies continuously over space and has to be flattened to a two dimensional map. There is no doubt that three-dimensional textured urban models are growing in popularity in the field of geo-visualization. The term ‘Geo’ refers exclusively to the geographical representation of GIS data in a ‘real world’ coordinate system which differentiates it from a ‘movie world’ arbitrary coordinate system. The increasing development of urban areas demands more now than ever of urban planners, which in turn demonstrate a growing, demand for 3D realistic visualization. While, the research in 3D GIS was progressing, it soon became a 3D spatial project, utilizing photogrammetry as a fundamental data collection technique. In this context photogrammetry is used as both a geometric data gathering tool and also as a remote sensing tool for information extraction. Field surveying prevailed in obtaining control points utilized in aerial triangulation and block adjustment used for processing of the data. Consequently, with resources and knowledge available from three separate but interlinked fields in spatial sciences, a GIS was created while explicitly concentrating on 3D Geo-Visualization. Introduction For many years, the most challenging issue in spatial sciences has been the handling of 3D Geo-Information, which has resulted in development of many software applications. The project aims & objectives comprised the initiation of 3D GIS, where the idea of integrating digital photogrammetry, remote sensing, surveying and GIS has intimidated many within the GIS community. The issues associated with the realization of this concept are discussed and some of the technical steps in applying this to Central Business District (CBD) Adelaide, South Australia are presented. While the research in 3D GIS was progressing, it soon became a 3D spatial project, utilizing photogrammetry as a fundamental data collection technique. In this context photogrammetry is used as both a geometric data gathering tool and also as a remote sensing tool for information extraction. Field surveying prevailed in obtaining control points utilized in aerial triangulation and block adjustment used for the processing of the data. Consequently, with resources and knowledge available from three separate but interlinked fields in spatial sciences, a GIS was created while unequivocally concentrating on 3D Geo-Visualization. The goal of the research was to develop a 3D realistic city model. This was carried out through the creation of footprints, reconstruction of buildings (see figure 1), photo realistic rendering and transformation to perspective fly-through and web based applications with Virtual Reality Modelling Language (VRML). The results of the research contribute to (1) the creation of 3D realistic models (2) updating and managing existing GIS footprints (3) 3D visualization in terms of geographical visualization and (4) storing original measurements on commercially available systems. In addition, the project explores Virtual Reality Modelling Language (VRML). Just producing visualization is not enough; it should be ensured that what is being produced is based on results and facts of appropriate information analysis.  The major conclusions of the project were:
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