Ověření geometrie

Aspose.GIS API vám umožňuje ověřovat geometrie pro řadu operací. Poskytuje vám možnost ověřit geometrii pro pravidla týkající se Geometrií, stejně jako specifikace podle Geospatial souborových formátů.

Kontrola platnosti geometrie

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
LinearRing linearRing = new LinearRing();
linearRing.AddPoint(0, 0);
linearRing.AddPoint(0, 1);
linearRing.AddPoint(1, 0);
bool valid = linearRing.IsValid; // valid == false
linearRing.AddPoint(0, 0);
valid = linearRing.IsValid; // valid == true

Kontrola jednoduchosti geometrie

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
LineString lineString = new LineString();
bool simple = lineString.IsSimple; // simple == true
lineString.AddPoint(0, 0);
lineString.AddPoint(1, 0);
simple = lineString.IsSimple; // simple == true
lineString.AddPoint(0.5, 0);
simple = lineString.IsSimple; // simple == false (line string crosses itself)

Ověření geometrií při zápisu

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
var exteriorRing = new LinearRing();
exteriorRing.AddPoint(0, 0);
exteriorRing.AddPoint(0, 1);
exteriorRing.AddPoint(1, 1);
exteriorRing.AddPoint(1, 0);
exteriorRing.AddPoint(0, 0);

var interiorRing = new LinearRing();
interiorRing.AddPoint(0.5, 0.5);
interiorRing.AddPoint(1, 0.5);
interiorRing.AddPoint(1, 1);
interiorRing.AddPoint(0.5, 1);
interiorRing.AddPoint(0.5, 0.5);

var invalidPolygon = new Polygon();
invalidPolygon.ExteriorRing = exteriorRing;
invalidPolygon.AddInteriorRing(interiorRing);
// invalidPolygon.IsValid == false, since polygon rings share segments (have infinite number of intersection points)

GeoJsonOptions options = new GeoJsonOptions();
options.ValidateGeometriesOnWrite = false; // false is default
File.Delete(dataDir + "not_validated_data_out.shp");
using (var nonValidatingLayer = Drivers.GeoJson.CreateLayer(dataDir + "not_validated_data_out.shp", options))
{
    Feature feature = nonValidatingLayer.ConstructFeature();
    feature.Geometry = invalidPolygon;
    // no exception is thrown, since ValidateGeometriesOnWrite == false, and GeoJson specification doesn't say that rings of polygon can't share segments.
    nonValidatingLayer.Add(feature);
}

options.ValidateGeometriesOnWrite = true;
File.Delete(dataDir + "validated_data_out.shp");
using (var validatingLayer = Drivers.GeoJson.CreateLayer(dataDir + "validated_data_out.shp", options))
{
    Feature feature = validatingLayer.ConstructFeature();
    feature.Geometry = invalidPolygon;
    try
    {
        validatingLayer.Add(feature); // GisException is thrown, since polygon is not valid
    }
    catch (GisException e)
    {
        Console.WriteLine(e.Message);
    }
}

Ověření geometrií při zápisu s dodržováním specifikací

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
LineString lineStrinWithOnePoint = new LineString();
lineStrinWithOnePoint.AddPoint(0, 0);

GeoJsonOptions options = new GeoJsonOptions();
options.ValidateGeometriesOnWrite = false;
using (var layer = Drivers.GeoJson.CreateLayer(dataDir + "ValidateOnWriteObeyingSpecifications_out.json", options))
{
    Feature feature = layer.ConstructFeature();
    // GeoJSON specification says that line string must have at least two coordinates.
    feature.Geometry = lineStrinWithOnePoint;

    try
    {
        // Geometry of feature doesn't match data format specification, so exception is thrown
        // regardless what ValidateGeometriesOnWrite option is.
        layer.Add(feature);
    }
    catch (GisException e)
    {
        Console.WriteLine(e.Message);
    }
}