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AVoronoi-andsurface-basedapproachfortheautomaticgenerationofdepth-contoursforhydrographiccharts

Muiden, March 27, 2013RaviPeters

@HydrographicSocietyBenelux

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HydrographicchartA chart of a waterbody intended for

safe ship navigation

Dienst der Hydrografie 2011

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Generalization

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Smoothing

Aggregation

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safety

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Constraint:

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safety

4

Constraint:

Image courtesy of Quality Positioning Services

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Otherconstraints

2. LegibilitySmooth contours > cluttered contours

3. TopologyNo intersections between contours

4. Morphology

Keep realistic relation to measurements

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Currentapproaches

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enera ization enera ization

Input points Grid Contour

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maxraster(profileview)

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Currentapproaches:

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maxraster(profileview)

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Currentapproaches:

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maxraster(profileview)

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Currentapproaches:

Not Safe!

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Myapproach(1D)No gridding! Use natural neighbours

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Myapproach(1D)No gridding! Use natural neighbours

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VoronoiDiagram

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Myapproach:

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smoothingoperator(1D)

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Myapproach:

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smoothingoperator(1D)

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Myapproach:

re-interpolate

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smoothingoperator(1D)

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Myapproach:

Keep shallowest one

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smoothingoperator(1D)

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Myapproach:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

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smoothingoperatorExperiments:

-

+

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reshapingoperator(1D)

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Myapproach:

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reshapingoperator(1D)

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Myapproach:

Steering points

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reshapingoperator(1D)

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Myapproach:

Steering points

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reshapingoperator(1D)

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Myapproach:

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reshapingoperatorExperiments:

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reshapingoperatorExperiments:

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currentsolutionsComparisonwith

IDW (r=5m,p=2) Double buffering (6m) Max Raster (5m) My approach (10x s, 3x d)

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Summary

Contour generalization for hydrographiccharts

Current methods are lacking(not always safe)

Voronoi- and surface-based approach

based on natural neighbours

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Questions?