Class Plan (11/10)

3D Fun Stuff Today!!

1. Task: Focus on Congress Avenue in Austin, TX
1. Create a TIN (Terrain Dataset Concepts)
   
2. Create a 3D Model
3. Create an AVI flythrough
4. Extrude buildings
5. View layers in Google Earth
2. Download Data
3. Definition of a TIN:

1. A triangulated irregular network data model (TIN) is an efficient way for representing continuous surfaces as a series of linked triangles. Although both grids and tins can be used for surface representation, tins are especially useful for representing surface elevation, subsurface elevation and terrain modeling, specially when the represented surfaces are highly variable and contain discontinuities and breaklines.

   A tin is formed by nodes, triangles and edges. Nodes are locations defined by x, y and z values from which a tin is constructed. Triangles are formed by connecting each node with its neighbors according to the Delaunay criterion: all sample points are connected with their two nearest neighbors to form triangles (by using this method the triangles are as equi-angular as possible, any point on the surface is as close as possible to a node, and the triangulation results independent of the order the points are processed). Edges are the sides of triangles.

   Tins are generated from points, polygons and lines. Points used in defining the tin are called mass points. Areas of constant elevation, such as water surfaces are called exclusion polygons. Finally, lines such as streams and shorelines are called breaklines. Breaklines can be either hard or soft. Hard features are things like roads, streams, and shorelines which indicate a significant break in slope. Soft features are things like ridgelines on rolling hills. Ridges like these do not represent distinct breaks in slope but since they separate watersheds you might like to maintain in the triangulation. When a tin is created, mass points become nodes of triangles, while breaklines and exclusion polygon boundaries become triangle edges.

4. Create a TIN from (1) raster and (2) contours
1. Be extremely careful of x,y,z coordinate systems as well as that of the data frame. Let's use NAD_1927_UTM_Zone_14N.
1. Useful Info: 1 foot = 0.3048 meters
   
5. View TINs in ArcScene
1. Drape various TIGER layers by setting the base heights
2. Drape trees (metadata)
   
3. Add the building footprints (metadata)
   
1. Set the base height
2. Set the extrude height
4. Create fly-through video using the Animation Toolbar
6. Export layers to KMZ
1. ArcToolbox/3D Analyst Tools/Conversion/To KML/