GIS 5935 - Surfaces - TINs and DEMs

Having moved on from the modules regarding data quality, this week we were introduced to surfaces and surface models, more specifically Triangulated Irregular Networks (TINs) and Demographic Elevation Models (DEMs). TINs are based on vector data and are made up of a series of linked triangles that vary in shape and size, but display a 3D representation of a surface. DEMs are based on raster data, more specifically the spot heights associated with each grid part of a raster. 

For this lab we were tasked with creating a TIN and DEM, as well as displaying contours based on both of them. We were then tasked with comparing the contours produced by both. Below I have included images of my results. 

(a) Contour lines based on the TIN

(b) Contour lines based on the DEM

The contours produced as a result of the TIN appear to be more jagged, while the contours produced from the DEM have a smoother appearance. There is also a noticeable difference between the derived contours in areas that have a steeper slope versus areas that have a more gentle slope. The difference between both sets of contours in steeper slopes are far less than in the gentler slopes. More specifically the contours produced from the TIN seem to be missing some details/contours in the areas of gentler slopes. This leads me to believe that the contours produced from the TIN is slightly less accurate. The smoothness of the contours produced as a result of the DEM also may more closely resemble the actual surface of the study area.

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