In our digital world of 3D modeling, virtual reality, and online and real-time viewing, mapping will never be the same. Flat printouts, created by contour lines that guessed at the actual dimensions of terrain elevation, are gone. The National Mapping Accuracy Standard of 1947 required no more than 10% of tested elevations be in error more than one-half of the contour interval. By contrast, NEXTMap data from Intermap Technologies has an average RMSE of .65 meters with an absolute contour accuracy of 7 feet. Internal analysis further indicates 3-foot contours can be accurately depicted.
Because it does not have polygon topology, contour data is not considered vector data. Contours have line topology; however, spatial topology is needed to perform accurate spatial analysis on vector data. Although certain software can identify what other spatial data objects intersect a particular contour, that’s all they can do. The fact is that accurate spatial analysis can only be performed on the data that created the contours, not the actual contour map itself.
By providing additional context, technology can be used to enhance 2D software applications in a 3D environment. This is accomplished by creating a triangulated irregular network (TIN). A TIN model more accurately represents a surface through a set of contiguous, non-overlapping triangles, thereby reflecting the actual 3D nature of the surface being mapped. Inside each triangle, created from a set of points called apexes, a plane represents the surface. TINs essentially help us turn flat maps into accurate depictions of the earth’s 3D surface.
First implemented in the 1970s to define surface models, TINs became more common in the 1980s thanks to the development of computer-aided design, or CAD. The development of 3D modeling and virtual realities in the 1990s allowed TINs to gain further importance and, with the growing availability of large-area height datasets and their associated viewing requirements, TINs grew to be extremely popular in the late ‘90s. The current requirements of online and real-time viewing in today’s real world make TINs an essential mapping. In the future, TIN will become an everyday technology for each of us. The world isn’t flat, of course; using digital mapping technology and depictions, our mapping surfaces can take on the actual dimensions of the earth which we live.
TIN mapping is essential when developing contour plots and survey drawings, surface design, volumetric calculations, surface visualization, architectural and 3D visualization, and GIS, as well as PND/PDA and SAT/Nav applications. Whenever an industry requires extremely accurate 3D depictions, TIN mapping can present the world as it actually is – without educated guesses or inaccurate contour lines.
TIN maps are created using DEM gridded data or irregular points. For a more complete picture, data can be combined from different sources and accuracies. There are many products available with which to create TINs from point datasets; some will even provide optimization of DEM data into TINs. By using multiple data points from a variety of sources that are then combined into a 3D mapping system, a real-world surface can be more accurately depicted.
TINs have growing applications in landscape modeling, 3D visualization, engineering and design applications, architectural visuals (that go beyond the traditional 2D blueprint), city modeling, and online planning and browsing. A 3D online model allows visitors to more accurately view the actual dimensions of an area of land, for instance. Aside from its daily practical applications, TIN technology is widely being used for movies and computer games that allow the digital world to portray a more accurate view of reality.