Predicting Vessel Movements on Water

Jim Taysom

Approved for Public Release – NGA Case #15-162

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(U) Purpose: To illustrate the use of farthest on circle analysis in the support of maritime intelligence.

(U) Bottom line: Farthest on circle analysis illustrates how long it takes to reach all accessible location from a starting point.

Farthest on Circle

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(U) Inputs for analysis• Speed of vessel• Endurance of vessel• Obstacles that hinder movement• Point of origin

(U) Outputs from analysis• Bands of equal time/distance from origin• File exported as image, feature class or kml

Process

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(U) Pros• Can be used for large areas• Precision error is regular• Small obstacles are taken into account

(U) Cons• Up to 8% shortfall in intermediate directions (NNE,

ENE, ESE, SSE, ect…)• Usually processed with assumed slack water

conditions

Raster Based Processing

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Raster Based Processing

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(U) Pros• No areas of shortfall• Consistently precise

(U) Cons• Greatly increased processing time• Obstacles smaller than the band width are ignored• Bands can skip over thin but long obstacles like

jetties• Must be processed with slack water conditions

Vector Based Processing

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Inner Iteration

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(U) Used for farthest on circle analysis• Depicts all accessible areas by a vessel• Useable for maritime operations• Estimates time need to reach an area

(U) Farthest on circle analysis illustrates how long it takes to reach all accessible locations

Discussion

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Approved for Public Release – NGA Case #15-162