The Oahu Area Model

Site of the

USS Greenville – Ehime Maru Collision

By Mark Lennerton

Key Coordinates for the VRML Map of Oahu

X = 0Y = 0 Z = 0

X = 0Y = 0 Z = -110,572

X = 147,569Y = 0 Z = -110,572

X = 147,569Y = 0 Z = 0

X = 61,000Y = 20,000 Z = 23,000

CollisionArea

Default viewpoint

Oahu

Molokai

Sources• The terrain was acquired from joining two DTED maps.• Natural sea floor depths less than 600 meters were

acquired from a bathymetric maps. The maps were texture mapped over the model created with the DTEDs and points along each 100 meter contour line were plotted as a vertices representing the depth.

• The above map was black and white and included a crude texture of Oahu. By isolating Oahu on the map and texture mapping it to the Oahu model with a green tint, a nice representation of an ‘ancient’ Oahu was achieved.

• Lat/Long lines were created by referencing DTED software applications.

Bathymetry Sourcehttp://walrus.wr.usgs.gov/pacmaps/hw_index.html

Oahu & Surrounding Bathymetry

Assumptions• All Y dimensions are exaggerated by a factor 1.5 to

increase terrain appreciation. Often 5.0 is used.• GeoVRML was purposely avoided. The intent was to

have a ‘useable’ background. Curvature of the surface would impair this effort.

• The entire see floor has an additional added depth of 50 meters to eliminate any floating point/”Z-buffer” error between see floor and sea surface at the shallow depths.

• The Ehime Maru rests at a depth of 2000’, or 610 meters, but in the model rests at 610 X 1.5 + 50, or Y = -980.

• Because no bathymetric info below 600 meters was available for the collision area, a reasonable estimation was made and modeled.

Registrations• 1 meter equals one unit in the X and Z directions.• The model area dimensions:

– X spans 147,569 meters of width– Z spans 110,572 meters of depth

• Each corner of the map registers at– Bottom left

• X = 0 and Z = 0 which equates to 15?-??W 2?-??N

– Bottom right• X = 147,569 and Z = 0 which equates to 15?-??W 2?-??N

– Top left• X = 0 and Z = -110,572 which equates to 15?-??W 2?-??N

– Top right• X = 147,569 and Z = -110,572 which equates to 15?-??W 2?-??N

Conversions• The area of the collision is bounded by

– Bottom left• 21-00N 157-55W which equates to X = ______, and Z = ______.

– Bottom right• 21-00N 157-45W which equates to X = ______, and Z = ______.

– Top left• 21-10N 157-55W which equates to X = ______, and Z = ______.

– Top right• 21-10N 157-45W which equates to X = ______, and Z = ______.

• Conversions– One degree of latitude equals _____ meters in the Z axis.– One degree of longitude equals _____ meters in the X axis.

Remaining Tasks

• Texture Molokai • Incorporate a sky and underlying sea floor

background• Incorporate the Collision USS Greenville - Ehime

Mari scenario– Properly convert all waypoints from the existing

scenario to this implementations– Create additional telltale viewpoints

• Incorporate the heads-up display

X3D-Edit Application

Contact Page

• Mark Lennerton (MS in CS student)

• Naval Postgraduate School

1 University Circle

Code 32/Dept 03

Monterey CA 93943-5000

• Email– mjlenne1@nps.navy.mil

• Don Brutzman (Professor)• Naval Postgraduate School

1 University Circle Code UW/Br Root 200 Monterey CA 93943-5000• Phone

– Work 831-656-2149– Fax 831-656-3679

• Email– Brutzman@nps.navy.mil

• Url– http://web.nps.navy.mil/~brutzma

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