Computer software
can build terrain surfaces by interpolating between surveyed contour lines on a map.
Computer software can model terrain surfaces for contour mapping by using interpolation to estimate and derive information between data points provided by a survey. Kriging and triangulation are two interpolation options in mapping software, each possessing advantages and disadvantages for different mapping situations.
Significance of Interpolation Method Choice
The interpolation method chosen in contour mapping can affect the accuracy of the resulting surface, depending on the spread of original data. Interpolation methods are programmed to make different assumptions based on surrounding information. For this reason, some data sets or mapping objectives lend themselves better to one interpolation method over another. The goal of choosing the right interpolation method is to generate surfaces to a degree of accuracy for representation, analysis or assessments.
The Kriging Method
The kriging interpolation method uses a grid of equally spaced data points to generate surfaces. This method uses weighted moving averaging, in assuming that one pattern of variation can be applied across the surface it defines from the set of data. The goal of kriging is not to directly mimic reality, but to follow the general trends shown by data points.
The Triangulation Method
Interpolation by triangulation is a very flexible method that can create a surface quickly from different types of data sources. Rather than using a grid, the triangulation method defines a surface from irregularly spaced points. This characteristic often results in more accurately defined features. Since triangulation does not average information during interpolation, it is better equipped to deal with data sets with abrupt peaks or changes. The triangulation method can be computed quickly because it uses fewer points than kriging, but it will not create as smooth of a surface. If appearance is a main mapping objective, triangulation might not be the best option.
Kriging vs. Triangulation
The kriging method has several advantages over triangulation and other interpolation methods in the general accuracy and lack of bias of the resultant surface. Estimates in kriging have a known minimum degree of variation, so a calculation of confidence across surfaces can be determined. Further, the method is beneficial to data analysis by showing gaps in information. The resultant surface from kriging is averaged, so while it is generally accurate, it does not necessarily honor original data points. Triangulation surfaces accurately follow original data, but are less capable of extrapolating information or trends beyond an original data set.
