Contours, as with rasters, are not the best source of data from which to build a Terrain. Rather, Terrains should be used to make contours. If there's no other source of information, contours can be used. It's recommended they be stored in a 2D polyline feature class with an attribute for height, considering that for each feature the height of every vertex is the same. They should be included in the Terrain using an SFType of mass point. Soft line is also a possibility, but it is less efficient. However, to use contours in a Terrain, the point spacing must be obtained, which can be done using a few tools from the 3D Analyst toolbox and Data Management toolbox.
Instructions provided describe how to locate the point spacing of contour data for use in a Terrain. Both the 3D Analyst extension and an ArcInfo license are required to perform the following steps.
- Open ArcToolbox > Data Management Tools > Features. Open the Feature Vertices to Point tool (To use/see this tool the ArcInfo license is required). Input the contour data which must be 3D and select an output location. Click OK and let the tool run.
- Go to 3D Analyst Tools > Conversion > From Feature Class > Feature Class Z to ASCII. Input the points created in Step 1. Specify an output location and then an output name. Leave the Output File Format as Generate. Click OK and let the tool run.
- Go to 3D Analyst Tools > Conversion > From File and open Point File Information. Input the text file created from Step 2. Select an output feature class location and change Input File Format to Generate. Click OK and let the tool run.
- Open the Attribute Table of the output feature class from Step 3 to find point spacing information, which can then be entered into the Terrain tools.