Geodetic Polygon Rendering Across Splitting Meridian

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Solution Overview

Problem

Existing geospatial applications face difficulties in accurately drawing geodetic polygons that straddle a splitting meridian on cylindrical projections, as they require users to split such polygons into multiple non-straddling polygons, leading to inaccurate visual representation and increased query requirements.

Innovation Solution

A method for drawing geodetic polygons that straddle a splitting meridian by transforming geographic coordinates into planar coordinates, adjusting positions to maintain the polygon's integrity across the meridian, and displaying the polygon as a whole, eliminating the need for multiple substitute polygons.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a geodetic polygon straddles a splitting meridian on a cylindrical projection, then the polygon can represent a continuous geographic area, but the cylindrical projection edges intersect the polygon causing visual distortion and rendering problems

Engineering Contradiction:

Improveaccuracy of geographic representationVSAvoidvisual representation of polygon

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent segments the straddling geodetic polygon into multiple non-straddling geodetic polygons by introducing split lines along the splitting meridian. This segmentation allows each sub-polygon to be rendered independently without crossing the cylindrical projection edges, eliminating the visual distortion while preserving the original polygon's geographic meaning through metadata association.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary data structure that stores the relationship between the original straddling polygon and its segmented sub-polygons. This intermediary layer enables the system to render multiple sub-polygons while maintaining the semantic integrity of the original single polygon, allowing accurate visual representation without direct intersection with projection edges.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If a user defines multiple substitute non-straddling polygons to replace a single straddling polygon, then the polygons can be displayed without crossing the splitting meridian, but the user interface becomes more complex and the area coverage becomes inaccurate

Engineering Contradiction:

Improveease of polygon creationVSAvoidaccuracy of polygon area and perimeter

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent implements automatic polygon segmentation functionality that performs the splitting operation automatically when a polygon is detected to straddle the splitting meridian. This self-service mechanism eliminates the need for users to manually create multiple substitute polygons, simplifying the user interface while maintaining precise area and perimeter calculations through the automated segmentation process.

Inventive Principle:

Principle #25Self-service

3Reliability

If multiple substitute polygons are used to represent a straddling polygon, then the display can avoid edge intersections, but multiple buffering operations and geospatial queries must be performed increasing computational complexity

Engineering Contradiction:

Improvecorrect rendering without edge intersectionsVSAvoidnumber of buffering operations and queries

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the processing of multiple segmented polygons by implementing a unified buffering operation that processes all sub-polygons simultaneously while preserving their spatial relationships. This merging approach reduces the number of separate buffering operations and geospatial queries needed, decreasing computational complexity while maintaining correct rendering of the original straddling polygon's buffer zones.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If the splitting meridian is chosen as the 180th meridian for cylindrical projection, then the projection follows conventional cartographic standards, but polygons crossing this meridian cannot be displayed as continuous features

Engineering Contradiction:

Improvecompatibility with standard map projectionsVSAvoidcontinuous representation of geographic features

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent creates copies of the straddling polygon's geometric data for each segment, storing them as separate non-straddling geodetic polygons while maintaining metadata that references the original single polygon. This copying approach allows the system to work with standard cylindrical projections using the 180th meridian convention while preserving the continuous representation of geographic features through the segmented copies that together represent the original uninterrupted polygon.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS8085268B2Techniques for drawing geodetic polygons

Publication Date: 2011.12.27 PALANTIR TECHNOLOGIES INC

AI summary

Techniques in a data processor for drawing on a map a geodetic polygon that straddles a splitting meridian include, in one embodiment, maintaining data that represents the geodetic polygon, the data comprising a set of geographic coordinates; transforming the set of geographic coordinates into a set of planar coordinates representing a planar polygon; splitting the planar polygon into a plurality of sub-figures; shifting at least one sub-figure of the plurality of sub-figures along a horizontal axis of two-dimensional plane to produce a shifted sub-figure; and causing the shifted sub-figure to be displayed on a map concurrently with at least one other sub-figure of the plurality of sub-figures that was not shifted.