Surfaces - TINs and DEMs

This week, I explored two elevation models: Triangulated Irregular Networks (TINs) and Digital Elevation Models (DEMs). Both create 3D terrains but differ in how they're generated and represented. Using ArcGIS Pro, I worked through various elevation data models and analysis techniques. Below is a brief overview of each part with screen captures illustrating key steps and findings.

Part A: Exploring Elevation Points and Vertical Exaggeration

• I added TIN to a Local Scene in ArcGIS Pro and set it as the elevation source to visualize the terrain in 3D. Then, I draped a radar image over the TIN. To better see terrain features, I increased the vertical exaggeration to 2.0.

Figure 1: Close-up of the radar image draped over the TIN with vertical exaggeration applied.

Part B: Using a DEM to Develop a Ski Run Suitability Map

• Using a DEM, I created a ski run suitability map by analyzing key terrain factors for ski planning: elevation, slope, and aspect. Each factor was reclassified and combined with weighted importance, highlighting the best areas for new runs. The 3D visualization (Figure 2) shows how terrain and suitability intersect, helping identify optimal ski zones.

Figure 2. Ski run suitability map with terrain exaggerated for clarity.

Part C: Exploring TINs

• I explored the another TIN to better understand terrain characteristics by applying different symbology options: surface elevation, slope, and aspect. Adding triangle edges helped visualize the TIN’s structure and extract detailed values. The final symbology (Figure 3) uses graduated colors for slope, distinct edges, and contours to clearly represent terrain features.

Figure 3: TIN visualization showing slope gradation, edges, and contours.

Part D: Creating and Analyzing TINs

• I created a TIN using elevation points clipped by a study boundary polygon, then compared contour lines derived from the TIN and from a spline-interpolated DEM. The TIN contours are more angular, reflecting the triangular network, while the DEM contours are smoother due to interpolation. Differences are most noticeable in areas with sparse elevation points, affecting contour accuracy (Figure 4).

Figure 4: Comparison of contour lines from TIN (angular) and DEM (smooth) with elevation points shown.