GEOS 3.14.0dev
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#include <CoveragePolygonValidator.h>
Public Member Functions | |
CoveragePolygonValidator (const Geometry *targetPolygon, std::vector< const Geometry * > &adjPolygons) | |
void | setGapWidth (double p_gapWidth) |
std::unique_ptr< Geometry > | validate () |
Static Public Member Functions | |
static std::unique_ptr< Geometry > | validate (const Geometry *targetPolygon, std::vector< const Geometry * > &adjPolygons) |
static std::unique_ptr< Geometry > | validate (const Geometry *targetPolygon, std::vector< const Geometry * > &adjPolygons, double gapWidth) |
Validates that a polygon forms a valid polygonal coverage with the set of polygons adjacent to it. If the polygon is coverage-valid an empty geos::geom::LineString
is returned. Otherwise, the result is a linear geometry containing the polygon boundary linework causing the invalidity.
A polygon is coverage-valid if:
The algorithm detects the following coverage errors:
If any of these errors is present, the target polygon does not form a valid coverage with the adjacent polygons.
The validity rules do not preclude gaps between coverage polygons. However, this class can detect narrow gaps, by specifying a maximum gap width using setGapWidth(double)
. Note that this will also identify narrow gaps separating disjoint coverage regions, and narrow gores. In some situations it may also produce false positives (i.e. linework identified as part of a gap which is wider than the given width). To fully identify gaps it maybe necessary to use CoverageUnion
and analyze the holes in the result to see if they are acceptable.
A polygon may be coverage-valid with respect to a set of surrounding polygons, but the collection as a whole may not form a clean coverage. For example, the target polygon boundary may be fully matched by adjacent boundary segments, but the adjacent set contains polygons which are not coverage-valid relative to other ones in the set. A coverage is valid only if every polygon in the coverage is coverage-valid. Use CoverageValidator
to validate an entire set of polygons.
The adjacent set may contain polygons which do not intersect the target polygon. These are effectively ignored during validation (but may decrease performance).
geos::coverage::CoveragePolygonValidator::CoveragePolygonValidator | ( | const Geometry * | targetPolygon, |
std::vector< const Geometry * > & | adjPolygons | ||
) |
Create a new validator.
If the gap width is specified, the set of surrounding polygons should include all polygons which are within the gap width distance of the target polygon.
targetPolygon | the geometry to validate |
adjPolygons | the adjacent polygons in the polygonal coverage |
void geos::coverage::CoveragePolygonValidator::setGapWidth | ( | double | p_gapWidth | ) |
Sets the maximum gap width, if narrow gaps are to be detected.
p_gapWidth | the maximum width of gaps to detect |
std::unique_ptr< Geometry > geos::coverage::CoveragePolygonValidator::validate | ( | ) |
Validates the coverage polygon against the set of adjacent polygons in the coverage.
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static |
Validates that a polygon is coverage-valid against the surrounding polygons in a polygonal coverage.
targetPolygon | the polygon to validate |
adjPolygons | the adjacent polygons |
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static |
Validates that a polygon is coverage-valid against the surrounding polygons in a polygonal coverage, and forms no gaps narrower than a specified width.
The set of surrounding polygons should include all polygons which are within the gap width distance of the target polygon.
targetPolygon | the polygon to validate |
adjPolygons | a collection of the adjacent polygons |
gapWidth | the maximum width of invalid gaps |