Todd Mitchell

GEOG-499c

Lab 5: Terrain and 3D Analysis

Question / Answer

 

Hand-In 1 (extract slope):

 

Hand-In 2 (extract aspect):

 

Hand-In 3 (hillshade 90 azimuth):

 

Hand-In 4 (hillshade 180 azimuth):

 

Hand-In 5 (viewshed creation):

 

Hand-In 6 (3D view):

 

Hand-In 7 (3D view with extrude):

 

Hand-In 8 (tin graph):

 

Hand-In 9

 

Hand-In 10

 

Hand-In 11

 

Hand-In 12

 

Hand-In 13

 

Hand-In 14-15

 

Hand-In 16

 

 

Answer the following questions

 

1. Think about an application where SLOPE, ASPECT, Viewshed can be used.

 

The planning of a scenic highway would require the use of slope to determine construction costs in allowing the new highway to follow the terrain efficiently. Aspect would help to show areas with adequate amount of sunlight, and viewshed would determine scenic viewpoints along the way.

 

2. Whatís the difference between Base Height and Extrude?

 

Base height is the elevation from the surface of the DEM being draped. An extrude extends the 2D features above or below the base to give a 3D appearance, turning points into vertical lines, lines into walls, and polygons into blocks. Extrusion helps to more easily convey depth or height.

 

3. What do TIN, SDTS, DEM stand for?

 

TIN stands for Triangular Irregular Network. The vertices of non-overlapping triangles contain x, y and z vector data. TINs are used to store and display surface models.

SDTS stands for Spatial Data Transfer Standard. This allows for exchanging databases without data loss across different platforms. It is also a federally adopted standard.

DEM stands for Digital Elevation Model. This is a raster representation of continuous elevation values to show terrain relief.