For this lab, we created and and explore TIN and DEM elevation data models. In this multiple part lab, we started with draping an image over a TIN surface and learned how to add an elevation source and change the vertical exaggeration. Next, we explored a DEM surface model and created a suitability map. I learned how to make a suitability map in my Applications of GIS course so this was a great refresher. I had to go back into the previous lab and review the Weighted Overlay Tool but other than that this step felt familiar to me. Then, we reviewed how to use the Appearance Tab for a TIN layer to change the symbology.
Above is a screen capture of the final model that I created showing TIN and DEM contour lines and compared the two sets of contour lines. One key difference between the two sets of contours is that the TIN contour lines are sharper while the DEM contour lines are smoother. Also, the TIN contour lines pass exactly through the elevation points while the DEM contour lines do not always pass through the points. The differences appear to be the greatest where the terrain is steep and where the elevation points are less dense. The differences smallest in the gently sloping areas. The TIN connects with the actual elevation points so the measurements match up exactly while the DEM smooths out the surfaces by averaging the points nearby so the hills and valleys look more gently sloping than they really are. Because of this, I believe the TIN contours are more accurate because they are matching with the original data and the DEM contours have a smoother but less precise representation of the terrain.
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