Measuring the accuracy of contour interpolated digital elevation models
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Photonirvachak
J. Indian Soc. Remote Sens. (March 2009) 37:139–146
RESEARCH ARTICLE
Measuring the Accuracy of Contour Interpolated Digital Elevation Models Arabinda Sharma . K.N. Tiwari . P.B.S. Bhadoria
Received: 30 May 2008 / Accepted: 11 March 2009
Keywords DEM accuracy . Interpolation techniques . Cell resolution . Stream network
Abstract Digital elevation models (DEM) are becoming increasingly important as tools in hydrological research and water resources management. Since error and uncertainty are inherently associated with spatial data, a complete evaluation of a DEM is of utmost importance before it is put into subsequent analysis. The present paper offers an innovative approach for quality assessment of contour interpolated DEMs of different resolutions. Five most frequently cited interpolation methods viz., TIN with linear interpolation, Inverse Distance Weighing, Thin Plate Spline, Ordinary Kriging and
A. Sharma ( ) . K.N. Tiwari . P.B.S. Bhadoria Agricultural & Food Engineering Department, Indian Institute of Technology, Kharagpur – 721302, West Bengal, India
email : [email protected]
TOPOGRID were selected for gridding of contours at five different resolutions i.e., 30m, 45m, 60m, 75m and 90m. In order to compare the quality of interpolated DEMs, a qualitative and quantitative evaluation of inter-polated DEMs for their vertical, horizontal and shape accuracy were carried out. It was found that different interpolation methods produced DEMs with different levels of artifacts. The analyses of vertical accuracy suggested that the variations were not pronounced in nature. However, the quantitative comparisons for horizontal and shape accuracy showed that there was a high level of disparity with significant differences among the interpolated DEMs.
Introduction As topography is a key controlling factor for the various natural processes, digital elevation model (DEM) has profound application in environmental issues including those of surface water hydrology
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(Darboux et al., 2002). Producing DEM by interpolating the contour line from topographic maps seems to be one of the most familiar ways of using digital elevation data in GIS. It has been known that several factors affect the quality of DEM by introducing errors that constitute uncertainty. In contour interpolated DEM, the choice of interpolation technique and grid size are two such factors on which the quality of DEM hugely depends upon (Wilson and Gallant, 2000). Hence, it is necessary to recognize the combined influence of these two factors on the DEM accuracy. There cannot be an interpolator that is best accepted universally. Again, higher resolution DEMs are generally assumed to be more precise but high precision implies high accuracy. Hence, search for the optimal DEM interpolation method and cell size has been a question of interest among spatial scientists in recent times. This has motivated many researchers to carry out comparative studies of interpolation accuracy for quite some time. Wood (1996) applied visualization tech
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