Maritime Boundary Median Line Generation

Using

Custom Avenue Scripts

by

Lorin Pruett, Kurt Christensen, and Hal Palmer

MRJ Technology Solutions

Since 1980, MRJ Technology Solutions, Fairfax, Virginia, USA, has been developing and maintaining a geospatial database of maritime information to support ocean engineering applications and regional environmental studies. The need to understand maritime boundaries (e.g., territorial sea limits, exclusive economic zones) led MRJ to create coverages that depict and document international agreements and country claims, both undisputed and disputed. Some of these coverages will be published in December 1999 as the Global Maritime Boundaries Database (GMBD) CD-ROM.

As part of the construction of the GMBD, MRJ developed a set of ArcView tools to improve the accuracy and repeatability of computationally derived median lines. These lines are used in areas where specific maritime boundaries between countries have not been declared. Countries may use an accurately computed median line as the basis to negotiate an agreed boundary. The ArcView tools will compute median lines given a set of attributed shoreline or baseline data and the reference ellipsoid. Users may also specify tolerances for the calculations and the output resolution. These new ArcView tools have other precision applications for similar types of computations on the ellipsoid.

Click here to start

MRJ Technology Solutions presents Maritime Boundary Median Line Generation Using Custom Avenue Scripts by Lorin Pruett, Kurt Christensen, and Hal Palmer

Maritime Boundary Background

The Global Maritime Boundaries Database (GMBD)

Elements of Maritime Boundaries

Boundary Line Complexities

MRJ Technology Solutions' ArcView Solution to the Median Line Problem

Comparison of Median Line from Old Source with Median Line Generated by MRJ's ArcView Avenue Scripts. Median Line Control Reference Lines are Also Shown.

Last Point Control and Source Reference Lines. Source Reference Lines are Useful for Control Feature Identification Especially During Agreed Boundary Negotiation

The Numerous Control Features are Automatically Chosen by the Avenue Tools. The Control Features Determine the Position of the Median Line

Manual Selection of Control Points by an Individual Would be a Daunting Task and Would Not be Nearly as Thorough or Accurate as Automatic Selection

The Avenue Tools Choose Route to Take at River Mouth and 90° Turn by Using the Attribute Information of the Features.

The River Detail Shows the Numerous Control Points Used in Median Line Determination. The River is Over 100 NMI Long from the Strait to the Land Boundary

This River Bend Details the Need for Automatic Control Point Selection

The Tools Perform Between-Vertex Interpolation of the Control Features. This is Necessary Because the Vertices May Not be the Closest Points of the Opposing Shorelines.

The Rest of the River Boundary - Imagine Hand-Picking All of These Control Points.

Land Fall - Even at a 10 Mile River Width There is a 1/2 NMI Difference Between the Calculated Line and the Old Median Line

Gulf of Aqaba - Example of Tri-Point Derivation for the Boundary of Three Countries

Tri-Point Locations Of Median Line for Three Countries is Automatically Performed

Detail of Control Features of the Tri-Points

The Construction of A Tri-Point Showing its Controlling Features

Summary of The Median Line Generation Program

Authors:
Lorin Pruett
Senior GIS and Data Analyst
MRJ Technology Solutions

Kurt Christensen
Engineering Specialist
MRJ Technology Solutions

Harold (Hal) Palmer
Senior Marine Scientist
MRJ Technology Solutions

Consulting Email: maritimeboundaries@mrj.com

Home Page: www.mrj.com

GMBD Sales Email: s.stone.elsevier.co.uk

Home Page: www.elsevier.com