Real-time 2D/3D display of DTED maps and evaluation of interpolation algorithms


Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Civil Engineering, Turkey

Approval Date: 2010

Student: ALİ DEMİR

Co-Supervisor: AHMET COŞAR, SEVDA ZUHAL AKYÜREK

Abstract:

In Geographic Information System (GIS) applications, aster data constitutes one of the major data types. The displaying of the raster data has an important part in GIS applications. Digital Terrain Elevation Data (DTED) is one of the raster data types, which is used as the main data source in this thesis. The DTED data is displayed on the screen as digital images as a pixel value, which is represented in gray scale, corresponding to an elevation (texel). To draw the images, the texel values are mostly interpolated in order to perform zoom-in and/or zoom-out operations on the concerned area. We implement and compare four types of interpolation methods, nearest neighbor, bilinear interpolation, and two new proposed interpolation methods (1) 4-texel weighted average and (2) 8-texel weighted average. The real-time graphical display, with zoom-in/zoom-out capabilities, has also been implemented by buffering DTED data in memory and using a C++ clas that manages graphical operations (zoom-in, zoom-out, and 2D, 3D isplay) by using Windows GDI+ and OpenGL graphic ibraries resulting in 30-40 framesper-second for one grid of DTED Level 0 data.