Validation de la géométrie

L’API Aspose.GIS vous permet de valider les géométries pour un certain nombre d’opérations. Elle vous fournit la possibilité de valider une géométrie par rapport aux règles relatives aux Géométries ainsi qu’aux spécifications des formats de fichiers géospatiaux.

Vérification de la validité de la géométrie

// 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

Vérification de la simplicité de la géométrie

// 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)

Valider les géométries lors de l’écriture

// 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);
    }
}

Valider les géométries lors de l’écriture en respectant les spécifications

// 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);
    }
}