Introducing Geographic Information Systems with ArcGIS: A Workbook Approach to Learning GIS, 3rd Edition

Creating a Map of Contour Lines

Contours showing elevation can be created from a DEM surface or a TIN surface.

____ 45. Locate the tool Contour (3D Analyst), which makes contour lines from a DEM. Run the tool. The Input raster is the DEM -- Kriging_Site1. Call the “Output polyline features” Dig_Zone_Contours. Make the Contour interval a quarter of a meter: 0.25 meters. Click OK. The contours will be added to the map. Make the contours bright red lines of width 1. Use the Identify tool to look at individual contours, paying attention to the Contour field. Again, you can compare the contour height with the MapTip generated by the DEM. You can also open the attribute table of Dig_Zone_Contours.

____ 46. Locate the Surface Contour tool, which makes contour lines from a TIN. Repeat the step above, but use the TIN (or Terrain) as the input data source. Make the name Site_TIN_Contours. Make the contour lines bright blue. Turn off everything except the two contour line feature classes. Which set of lines do you like better? ____________ Why? _________________________________ Save the map under any name you choose. ________________________

You have now seen three distinctly different ways of representing a surface—DEM, TIN, and contour lines. Each has its advantages and disadvantages. Each was, directly or indirectly, created from an initial set of measured points. The ways in which you created these representations are not the only ones; there are many others. In a real project, ...