Kỹ thuật nội suy cho mô hình hóa bề mặt địa hình 6,1 Các kỹ thuật nội suy: TỔNG QUAN Nội suy là một vấn đề gần đúng trong toán học và vấn đề là một ước tính trong thống kê. Nội suy trong mô hình địa hình kỹ thuật số được sử dụng để xác định giá trị chiều cao của một điểm bằng cách sử dụng chiều cao của các điểm lân cận. Có hai giả định tiềm ẩn đằng sau các kỹ thuật nội suy: (a) bề mặt địa hình là liên tục và trơn tru và (b) có một. | CHAPTER 6 Interpolation Techniques for Terrain Surface Modeling INTERPOLATION TECHNIQUES AN OVERVIEW Interpolation is an approximation problem in mathematics and an estimation problem in statistics. Interpolation in digital terrain modeling is used to determine the height value of a point by using the known heights of neighboring points. There are two implicit assumptions behind interpolation techniques a the terrain surface is continuous and smooth and b there is a high correlation between the neighboring data points. Interpolation is one of the core techniques in digital terrain modeling because it is involved in the various stages of the modeling process such as quality control surface reconstruction accuracy assessment terrain analysis and applications. Interpolation techniques can be classified according to different criteria and they can be used for different purposes. Table attempts to provide a simple classification. By the size of the area for interpolation two approaches are identified Petrie 1990a that is area based and point based. In the area-based approach the surface is constructed by using all the reference known points within this area and the height of any point within this area can be determined by using this constructed surface. Area-based interpolation could be either global or local. Global interpolation involves the construction of a single complex 3-D surface from the complete data set of measured points from which the height values of all other points can be obtained. This is an extreme approach. The usefulness of this type of technique depends on the complexity of the terrain surface and the actual size of the area. A more adaptive solution is to divide a large area into a series of patches of identical shape and size. This is called local or patchwise interpolation. A surface is constructed for each patch by using all the reference points and heights of all points to be interpolated within this patch are obtained from this patch .
