Triangulated Irregular Network Lab

    A TIN is a surface representation derived from irregularly space sample points and breakline features.  The TIN dataset includes topological relationships between points and their neighboring triangles.  Each sample point has an x,y coordinate and a surface or z-value.  These points are connected by edges to form a set of non-overlapping triangles used to represent the surface.

Project Setup

• Save the following data to the hard drive or your disk: TIN_Lab
• Unzip the data using Enzip (open the data, then extract).
• Start ArcMap
• From the main menu select Tools - Extensions, then check 3D Analyst.  Close the Extensions box.
• Under View, select Toolbars - 3D Analyst.
• Right click on the data frame, select Properties then click the General tab.  Set the map units to meters and the display units to kilometers.  Click OK.
• Click the Add data button.  Navigate to the folder where you unzipped the data and add contours.shp and tinbnd.shp. 

• Using the contour.shp layer, a TIN will be constructed to represent the terrain of Canyonlands National Park.
• Under the 3D dropdown menu select Create/Modify TIN - Create TIN from features.
• Select both contours and tinbnd under layers. 
• Highlight contours and change the following parameters:

                Height Source: Contour

                Triangulate as:  Mass points

                Tag Value Field:  None

• Highlight tinbnd and change the following parameters:

                Height Source:  None

                Triangulate as:  Soft line

                Tag Value Field:  None

•  Navigate to where you want to save this file and save it as Canyonlands.  Click OK.

Analyzing Visibility - Creating a Visibility Surface

• Add trail_lookout.shp to the view.
• Develop a visibility grid.  Under the 3D Analyst menu, select Surface analysis - Viewshed.  Change the following parameters:

                    Input Surface:  Canyonlands

                    Observer Points:   trail_lookout

                    Z Factor:  2

                    Output cell size:  1

• Navigate to where you want to save this file and save it as View. The calculation may take a few minutes.
• Move View above Canyonlands in the table of contents.
• Right click on Canyonlands - Properties - Display and change the Transparency to 10%.

3D Scene - View Themes in 3 Dimensions

• Click the ArcScene button in the 3D Analyst menu.  This opens an ArcScene window.
• Copy Canyonlands trail_lookout and View into the ArcScene window.
• Right click on View in the table of contents in ArcScene and select Properties.  Click on the Base Heights tab and set "Obtain heights for layer from surface:" to your canyonlands file.  Click OK.  Change the base height of trail_lookout to Canyonlands also.
• Right click on Canyonlands - Properties - Display and set the Transparency to 10%.
• You can now view your analysis in 3D.
• Make a layout of your map that is in ArcMap.  Add a title, legend, north arrow and neatline to your map.
• Save as TIN.pdf

Kristie Raymond, Nov. 2002, updated by Eva Grund, Oct. 2004.