Educational Module #3: Spatial Educational Module #3: Spatial Analysis and 3D AnalysisAnalysis and 3D Analysis

Emily M. Larkin and Dawn WrightEmily M. Larkin and Dawn WrightDept. of Geosciences, Oregon State Dept. of Geosciences, Oregon State

UniversityUniversitySeptember, 2004September, 2004

(Larkin 2001)

ObjectivesObjectives• On completion of the project, you should be able

to:– Create a new shapefile.– Add data to a shapefile.– Convert a bathymetry grid to a 3D display– Complete viewshed and hillshade analyses– Select features using the attribute table– Buffer a shapefile. – Define: Viewshed and hillshade

HillshadeHillshade•Creates shading on a Digital Elevation

Model (DEM) or a bathymetry layer to make it appear three-dimensional

•Appearance depends on the azimuth and altitude of the imaginary light source used.– Azimuth—the direction from which the light

is coming (north = 0°, east = 90°--most common = 315°)

– Altitude—the angle above the horizon of the light source (most common = 45°)

HillshadeHillshade

ViewshedViewshed•Viewshed shows what can be seen

from a certain point on the landscape (i.e. “what can I see from the top of this hill”)

•A set of points must be created to make a viewshed surface

•Spatial analyst determines what can be seen from those points.

ViewshedViewshed

3D Marine Mapping3D Marine Mapping•ArcMap makes 2D maps•ArcScene makes 2.5D maps—cannot

actually calculate volumes, but can draw in 3D, based on depth or elevation information.

•Other software, such as Fledermaus is required to make truly 3D maps

3D Marine Mapping3D Marine Mapping• Triangulated

Irregular Network (TIN)—this is a file format that represents a surface in 3D.– It is created from a

surface, such as a bathymetry file.

TIN of Fagaitua Bay

MPA ProjectMPA Project•There are three federal MPAs in

American Samoa– Fagatele Bay NMS– National Park of American Samoa– Rose Atoll National Wildlife Sanctuary*

*This is the only no-take marine sanctuary in American Samoa

Marine Protected Area (MPA) Marine Protected Area (MPA) ProjectProject•Goals

– Produce a short (3-5 pages, double-spaced) proposal for a hypothetical marine protected area (MPA)

– Demonstrate the connection between GIS data on a computer screen and real-world problems

MPA ProjectMPA Project•Things to consider in your proposal:

– What kind of maps do you need? Make sure they are understandable for someone who is not familiar with GIS.

– Who might be affected by the MPA?– Why does your area need to be an MPA?– How you would address village concerns?– What kind of fishing, if any, will you allow?– How will you enforce the rules?

MPA ProjectMPA Project• Things to remember:

– This is a hypothetical MPA, not a proposal for a real one.

– There is no one right answer.– You can create any kind of reserve you want as

long as you can produce a strategy for getting your proposal accepted.

– You are free to use any resources you find helpful (e.g. Internet resources), just be sure to cite them.

Module #3Module #3•Bathymetry from Fagatele Bay National

Marine Sanctuary (FBNMS) and Fagaitua Bay

•Hillshade, viewshed analyses for FBNMS

•3D rendering of FBNMS•Coral Reef Ecosystem Division ground-

truth points for Fagaitua Bay