| Summary: | A digital map system with display based on Scalable Vector Graphics (SVG) display standard that are targeted for embedded platforms has been developed by earlier Final Year Project students in the School of Computer Engineering (SCE), in Nanyang Technological University (NTU). This report describes the investigations, researches and experimentations performed in the project, to further enhance the visual effect of the map display of the system. The focus of the project is to incorporate 3-Dimensional (3D) display concepts into the 2-Dimensional (2D) SVG based map display. In particular the perspective transformation and the sorting of 2D surfaces are implemented to provide 3D perspective viewing on 2D display, while largely retaining the SVG format for the map description such that it can be remain backward compatible with the standard SVG format. The project involves first the study and understanding of 3D perspective transformation and projection, together with the study of SVG displays function. SVG based 3D Object is defined using polygon surfaces, where the proper order of the surface rendered is critical in order to provide the correct perspective of the object displayed. For example, surfaces that are rendered first will be cover up (blocked) by those rendered later. Hence the incorrect layering order will provide the wrong display when viewing the 2D surfaces of the 3D object with respect to a Center of Projection (COP), or the viewing point. Investigation and comparisons of existing concepts available in the graphics world lead to the development of a new surface sorting concept that is specifically appropriate for the map display system considered here, consists of three different checks to determine the arrangement of surfaces before rendering in SVG format. In addition the SVG’s viewBox concept used to resolve the map’s distortion problem encountered is also utilized to provide a time-saving way of implementing visual interface controls that allow the user to manipulate the map without changing much of the map data. All these concepts lead to the creation of a demonstration program which integrate the newly-designed sorting concept and the refine version of perspective algorithm to test and verify the feasibility of applying the concepts for the map display.
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