在 C# 中使用 Esri Gdb 文件格式

ESRI File GeoDatabases (FileGDB)

ESRI File GeoDatabases (FileGDB) 是 GIS 软件中最广泛使用的原生格式之一。Aspose.GIS 使您能够使用 FileGDB 文件格式并迭代其要素。

迭代 FileGDB 文件中的图层

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
//File GDB is a multi layer format. This example shows how to open File GDB as a dataset (collection of layers) and access layers in it.
using (var dataset = Dataset.Open(dataDir + "ThreeLayers.gdb", Drivers.FileGdb))
{
    Console.WriteLine("FileGDB has {0} layers", dataset.LayersCount);
    for (int i = 0; i < dataset.LayersCount; ++i)
    {
        Console.WriteLine("Layer {0} name: {1}", i, dataset.GetLayerName(i));

        using (var layer = dataset.OpenLayerAt(i))
        {
            Console.WriteLine("Layer has {0} features", layer.Count);
            foreach (var feature in layer)
            {
                Console.WriteLine(feature.Geometry.AsText());
            }
        }
        Console.WriteLine("");
    }
}

将 FileGDB 转换为 GeoJSON

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
//This will convert FileGDB dataset with three layers into single layered GeoJSON.
VectorLayer.Convert(dataDir + "ThreeLayers.gdb", Drivers.FileGdb, dataDir + "ThreeLayers_out.json", Drivers.GeoJson);

将 FileGDB 作为图层读取

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
//FileGDB can still be opened as a single layer. In this case, the opened layer will merge all layers inside FileGDB.
using (var layer = VectorLayer.Open(dataDir + "ThreeLayers.gdb", Drivers.FileGdb))
{
    Console.WriteLine("All layers in FileGDB has {0} features", layer.Count);
    foreach (var feature in layer)
    {
        Console.WriteLine(feature.Geometry.AsText());
    }
}

将 ShapeFile 作为数据集打开

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
//FileGDB can still be opened as a single layer. In this case, the opened layer will merge all layers inside FileGDB.
using (var layer = VectorLayer.Open(dataDir + "ThreeLayers.gdb", Drivers.FileGdb))
{
    Console.WriteLine("All layers in FileGDB has {0} features", layer.Count);
    foreach (var feature in layer)
    {
        Console.WriteLine(feature.Geometry.AsText());
    }
}

将图层添加到 FileGDB 数据集

打开现有的 FileGDB 数据集并向其中添加新图层

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
// -- copy test dataset, to avoid modification of test data.

var path = RunExamples.GetDataDir() + "ThreeLayers.gdb";
var datasetPath = RunExamples.GetDataDir() + "AddLayerToFileGdbDataset_out.gdb";
RunExamples.CopyDirectory(path, datasetPath);

// --

using (var dataset = Dataset.Open(datasetPath, Drivers.FileGdb))
{
    Console.WriteLine(dataset.CanCreateLayers); // True

    using (var layer = dataset.CreateLayer("data", SpatialReferenceSystem.Wgs84))
    {
        layer.Attributes.Add(new FeatureAttribute("Name", AttributeDataType.String));
        var feature = layer.ConstructFeature();
        feature.SetValue("Name", "Name_1");
        feature.Geometry = new Point(12.21, 23.123, 20, -200);
        layer.Add(feature);
    }

    using (var layer = dataset.OpenLayer("data"))
    {
        Console.WriteLine(layer.Count); // 1
        Console.WriteLine(layer[0].GetValue<string>("Name")); // "Name_1"
    }
}

从 FileGDB 数据集中删除图层

打开现有的 FileGDB 数据集并从中删除图层。

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
// -- copy test dataset, to avoid modification of test data.

//var datasetPath = GetOutputPath(".gdb");
var path = RunExamples.GetDataDir() + "ThreeLayers.gdb";
var datasetPath = RunExamples.GetDataDir() + "RemoveLayersFromFileGdbDataset_out.gdb";
RunExamples.CopyDirectory(path, datasetPath);

// --

using (var dataset = Dataset.Open(datasetPath, Drivers.FileGdb))
{
    Console.WriteLine(dataset.CanRemoveLayers); // True

    Console.WriteLine(dataset.LayersCount); // 3

    // remove layer by index
    dataset.RemoveLayerAt(2);
    Console.WriteLine(dataset.LayersCount); // 2

    // remove layer by name
    dataset.RemoveLayer("layer1");
    Console.WriteLine(dataset.LayersCount); // 1
}

创建 FileGDB 数据集

创建一个新的 FileGDB 数据集并添加图层到其中。

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
Console.WriteLine(Drivers.FileGdb.CanCreateDatasets); // True
var path = RunExamples.GetDataDir() + "CreateFileGdbDataset_out.gdb";

using (var dataset = Dataset.Create(path, Drivers.FileGdb))
{
    Console.WriteLine(dataset.LayersCount); // 0

    using (var layer = dataset.CreateLayer("layer_1"))
    {
        layer.Attributes.Add(new FeatureAttribute("value", AttributeDataType.Integer));

        for (int i = 0; i < 10; ++i)
        {
            var feature = layer.ConstructFeature();
            feature.SetValue("value", i);
            feature.Geometry = new Point(i, i);
            layer.Add(feature);
        }
    }

    using (var layer = dataset.CreateLayer("layer_2"))
    {
        var feature = layer.ConstructFeature();
        feature.Geometry = new LineString(new[]
        {
            new Point(1, 2),
            new Point(3, 4),
        });
        layer.Add(feature);
    }

    Console.WriteLine(dataset.LayersCount); // 2
}

使用 VectorLayer API 创建带有单个图层的 FileGDB 数据集

此示例创建了一个使用 VectorLayer API 的带有单个图层的 FileGDB 数据集。

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
var path = RunExamples.GetDataDir() + "CreateFileGdbDatasetWithSingleLayer_out.gdb";
var options = new FileGdbOptions();
using (var layer = VectorLayer.Create(path, Drivers.FileGdb, options, SpatialReferenceSystem.Wgs84))
// this 'using' is equivalent to
// using (var dataset = Dataset.Create(path, Drivers.FileGdb))
// using (var layer = Dataset.CreateLayer("layer"))
{
    var feature = layer.ConstructFeature();
    feature.Geometry = new LineString(new[]
    {
        new Point(1, 2),
        new Point(3, 4),
    });
    layer.Add(feature);
}

using (var dataset = Dataset.Open(path, Drivers.FileGdb))
using (var layer = dataset.OpenLayer("layer"))
{
    Console.WriteLine("Features count: {0}", layer.Count); // 1
}

将 GeoJSON 图层转换为 FileGDB 数据集图层

在 FileGDB 中创建新图层，并将来自 GeoJSON 图层的数据添加到其中。

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
var geoJsonPath = RunExamples.GetDataDir() + "ConvertGeoJsonLayerToLayerInFileGdbDataset_out.json";
using (VectorLayer layer = VectorLayer.Create(geoJsonPath, Drivers.GeoJson))
{
    layer.Attributes.Add(new FeatureAttribute("name", AttributeDataType.String));
    layer.Attributes.Add(new FeatureAttribute("age", AttributeDataType.Integer));

    Feature firstFeature = layer.ConstructFeature();
    firstFeature.Geometry = new Point(33.97, -118.25);
    firstFeature.SetValue("name", "John");
    firstFeature.SetValue("age", 23);
    layer.Add(firstFeature);

    Feature secondFeature = layer.ConstructFeature();
    secondFeature.Geometry = new Point(35.81, -96.28);
    secondFeature.SetValue("name", "Mary");
    secondFeature.SetValue("age", 54);
    layer.Add(secondFeature);
}

// --

// -- copy test dataset, to avoid modification of test data.
            
var sourceFile = RunExamples.GetDataDir() + "ThreeLayers.gdb";
var destinationFile = RunExamples.GetDataDir() + "ThreeLayersCopy_out.gdb";
RunExamples.CopyDirectory(sourceFile, destinationFile);

// --

using (var geoJsonLayer = VectorLayer.Open(geoJsonPath, Drivers.GeoJson))
{
    using (var fileGdbDataset = Dataset.Open(destinationFile, Drivers.FileGdb))
    using (var fileGdbLayer = fileGdbDataset.CreateLayer("new_layer", SpatialReferenceSystem.Wgs84))
    {
        fileGdbLayer.CopyAttributes(geoJsonLayer);
        foreach (var feature in geoJsonLayer)
        {
            fileGdbLayer.Add(feature);
        }
    }
}

从 FileGDB 数据集图层读取 OBJECTID

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
using (var dataset = Dataset.Open(path, Drivers.FileGdb))
using (var layer = dataset.OpenLayer("layer"))
{
    foreach (var feature in layer)
    {
        Console.WriteLine(feature.GetValue<int>("OBJECTID"));
    }
}

为 FileGDB 图层指定精度网格

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
var path = RunExamples.GetDataDir() + "PrecisionGrid_out.gdb";
using (var dataset = Dataset.Create(path, Drivers.FileGdb))
{
    var options = new FileGdbOptions
    {
        // specify coordinate precision grid parameters (origins and scales for coordinates)
        CoordinatePrecisionGrid = new FileGdbCoordinatePrecisionGrid
        {
            // all our coordinates must be more than (-400, -400) point
            XOrigin = -400,
            YOrigin = -400,

            // the write precision is 10 digits after the decimal point
            XYScale = 1e10,

            // M values are started at 0 and precision is 4 digits after the decimal point
            MOrigin = 0,
            MScale = 1e4,
        },

        // throw whenever an attempt to write coordinate that does not fit precision grid is detected
        EnsureValidCoordinatesRange = true,
    };

    using (var layer = dataset.CreateLayer("layer_name", options, SpatialReferenceSystem.Wgs84))
    {
        var feature = layer.ConstructFeature();
        feature.Geometry = new Point(10, 20) { M = 10.1282 };
        layer.Add(feature);

        feature = layer.ConstructFeature();
        // X == -410 is less than XOrigin, so an exception is thrown
        feature.Geometry = new Point(-410, 0) { M = 20.2343 };
        try
        {
            layer.Add(feature);
        }
        catch (GisException e)
        {
            Console.WriteLine(e.Message); // X value -410 is out of valid range.
        }
    }
}

为 FileGDB 图层指定容差

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
var path = RunExamples.GetDataDir() + "TolerancesForFileGdbLayer_out.gdb";
using (var dataset = Dataset.Create(path, Drivers.FileGdb))
{
    var options = new FileGdbOptions
    {
        XYTolerance = 0.001,
        ZTolerance = 0.1,
        MTolerance = 0.1,
    };

    using (var layer = dataset.CreateLayer("layer_name", options))
    {
        // layer is created with the provided tolerances and some ArcGIS features/tools will use it
    }
}

指定 ObjectId 和 Geometry 字段的名称

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
var path = RunExamples.GetDataDir() + "NamesOfObjectIdAndGeometryFields_out.gdb";
using (var dataset = Dataset.Create(path, Drivers.FileGdb))
{
    var options = new FileGdbOptions
    {
        // name object ID field 'OID' rather than the default 'OBJECTID'.
        ObjectIdFieldName = "OID",

        // name geometry field 'POINT' rather than the default 'SHAPE'.
        GeometryFieldName = "POINT",
    };

    using (var layer = dataset.CreateLayer("layer_name", options, SpatialReferenceSystem.Wgs84))
    {
        var feature = layer.ConstructFeature();
        feature.Geometry = new Point(12.32, 34.21);
        layer.Add(feature);
    }

    using (var layer = dataset.OpenLayer("layer_name"))
    {
        var feature = layer[0];
        Console.WriteLine(feature.GetValue<int>("OID")); // 1
    }
}