The Third Spatial Dimension - Introducing Geographic Information Systems with ArcGIS - page 551

36. Right-click on the Mt_P.txt Events entry and select Data > Export Data. For Output feature class
click the browse folder. Navigate to
___ IGIS-Arc_ YourInitials \Elevation_Data\The_Dig\Mount_Paolo.gdb\Dig_Zone
This should appear in the “Look in” field in the Saving Data window. Type Site in the Name field.
Make sure that you pick File and Personal Geodatabase feature classes from the Save as type
drop-down menu. Click Save. In the Export Data window click OK. Add the exported data (Site)
to the map if it doesn't happen automatically.
37. Use Search to find Create TIN (3D Analyst). Where is the tool?
_______________________________ Start the tool. (In version 10.0 this tool creates only an
empty TIN; you will use Edit TIN to supply the data. In 10.1 the behavior is different.)
38. For the Output TIN window field browse to
IGIS-Arc_ YourInitials \Elevation_Data\The_Dig
For the Name type Site_TIN. Click Save. Provide the correct spatial reference (UTM zone 30
north). Click OK. For Input Feature Class use Site. Click on the box below Height Field, and pick
Elev_MSL from the drop-down menu. Click OK. When the tool finishes, you should see Site_TIN
displayed as the map. Remove the Mt_P.txt Events entry from the Table of Contents.
39. Use the Identify tool to look at both the points of Site and the triangles of Site_TIN. Pick a
triangle, zoom in on it, and write down the elevations of its three vertices.
_________ ______________ _______________
Now write down the elevation, slope and aspect of a point near the middle of the triangle.
_________ ______________ _______________
Creating the TIN from a table of points is a bit convoluted, but the surface is a great way to
represent elevation.
Creating DEM files with Kriging
Assume now that you show the results to the archeologist. She is suitably impressed but she is really
used to contour lines and would like to see an elevation map in that form. Not a problem.
There are many ways to obtain three-dimensional surfaces from a discrete set of zero-dimensional points.
None is exactly right (recall, there is no “exactly” with GIS points, lines, and surfaces, nor is there any
“exactly” in any real-world coordinate set), but we can get “close.” We will use the mathematical method
called Kriging that you met before to create a digital elevation model (DEM, composed of square elevation
posts). We will then use the DEM to make contour lines. If you are faced with a real-world problem of this