Module 2.1: TINs and DEMs

 Module 2.1: TINs and DEMs

This weeks module was using continuous surface in TIN and DEM models to represent elevation. One would use TIN for vector data models and DEM for raster data models. You can use either one to represent your data it just depends on what you are trying to present.

When doing the exercise for the module there were different ways we tried to represent the data but the one that I am going to talk about is how the contour lines were presented by using TIN or DEM. TIN stands for Triangulated Irregular Network and is created out of elevation points. A Digital Elevation Model or DEM is a digital representation of a topographic surface. This is also created from the same elevation points. The image below shows how the elevation points were able to show the different contour lines from TIN and DEM. It is important to note that the black and red lines are from the TIN data set and the gray lines are from the DEM data set.

The key differences between the two contour lines are that the DEM contour lines are smoother whereas the TIN contour lines are very sharp. Another difference is that the DEM contour lines showed more in the higher points than the TIN contour lines. It looks like the greatest difference is where the higher numbers were located. There are more DEM contour lines. The smallest difference was where the lower numbers are located for both the DEM and TIN contour lines. I would say these differences were because there were more points in the lower numbers compared to the higher numbers. Lastly, of the two sets of contour lines I would say the DEM is more accurate.

When trying to know if you should use TIN or DEM it depends on how you are getting your data. TIN is usually not widely available and has been made for the specific study. Whereas, DEM have various resolutions and used for larger study areas. Luckily with new data collections such as LiDAR it makes the differences between DEMs and TINs obsolete. It is all based on how you want to represent your data.