geos::coverage::CoverageValidator Class Reference

#include <CoverageValidator.h>

Public Member Functions
	CoverageValidator (std::vector< const Geometry * > &coverage)
void	setGapWidth (double gapWidth)
std::vector< std::unique_ptr< Geometry > >	validate ()

Static Public Member Functions
static bool	isValid (std::vector< const Geometry * > &coverage)
static bool	hasInvalidResult (const std::vector< std::unique_ptr< Geometry > > &validateResult)
static std::vector< std::unique_ptr< Geometry > >	validate (std::vector< const Geometry * > &coverage)
static std::vector< std::unique_ptr< Geometry > >	validate (std::vector< const Geometry * > &coverage, double gapWidth)

Detailed Description

Validates a polygonal coverage, and returns the locations of invalid polygon boundary segments if found.

A polygonal coverage is a set of polygons which may be edge-adjacent but do not overlap. Coverage algorithms (such as CoverageUnion or simplification) generally require the input coverage to be valid to produce correct results. A polygonal coverage is valid if:

• The interiors of all polygons do not intersect (are disjoint). This is the case if no polygon has a boundary which intersects the interior of another polygon, and no two polygons are identical.
• If the boundaries of polygons intersect, the vertices and line segments of the intersection match exactly.

A valid coverage may contain holes (regions of no coverage). Sometimes it is desired to detect whether coverages contain narrow gaps between polygons (which can be a result of digitizing error or misaligned data). This class can detect narrow gaps, by specifying a maximum gap width using setGapWidth(double). Note that this also identifies narrow gaps separating disjoint coverage regions, and narrow gores. In some situations it may also produce false positives (linework identified as part of a gap which is actually wider). See CoverageGapFinder for an alternate way to detect gaps which may be more accurate.

Author

Martin Davis

Member Function Documentation

hasInvalidResult()

static bool geos::coverage::CoverageValidator::hasInvalidResult ( const std::vector< std::unique_ptr< Geometry > > &  validateResult )

static

Tests if some element of an array of geometries is a coverage invalidity indicator.

Parameters

validateResult

an array produced by a polygonal coverage validation

Returns

true if the result has at least one invalid indicator

isValid()

static bool geos::coverage::CoverageValidator::isValid ( std::vector< const Geometry * > &  coverage )

static

Tests whether a polygonal coverage is valid.

Parameters

coverage

an array of polygons forming a coverage

Returns

true if the coverage is valid

setGapWidth()

void geos::coverage::CoverageValidator::setGapWidth ( double  gapWidth )

inline

Sets the maximum gap width, if narrow gaps are to be detected.

Parameters

gapWidth

the maximum width of gaps to detect

validate() [1/3]

std::vector< std::unique_ptr< Geometry > > geos::coverage::CoverageValidator::validate

(

)

Validates the polygonal coverage. The result is an array of the same size as the input coverage. Each array entry is either null, or if the polygon does not form a valid coverage, a linear geometry containing the boundary segments which intersect polygon interiors, which are mismatched, or form gaps (if checked).

Returns

an array of nulls or linear geometries

validate() [2/3]

static std::vector< std::unique_ptr< Geometry > > geos::coverage::CoverageValidator::validate ( std::vector< const Geometry * > &  coverage )

static

Validates that a set of polygons forms a valid polygonal coverage. The result is a list of the same length as the input, containing for each input geometry either a linear geometry indicating the locations of invalidities, or a null if the geometry is coverage-valid.

Parameters

coverage

an array of polygons forming a coverage

Returns

an array of linear geometries indicating coverage errors, or nulls

validate() [3/3]

static std::vector< std::unique_ptr< Geometry > > geos::coverage::CoverageValidator::validate ( std::vector< const Geometry * > &  coverage, double  gapWidth  )

static

Validates that a set of polygons forms a valid polygonal coverage and contains no gaps narrower than a specified width. The result is a list of the same length as the input, containing for each input geometry either a linear geometry indicating the locations of invalidities, or a null if the geometry is coverage-valid.

Parameters

coverage	an array of polygons forming a coverage
gapWidth	the maximum width of invalid gaps

Returns

an array of linear geometries indicating coverage errors, or nulls

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The documentation for this class was generated from the following file:

• CoverageValidator.h