使用SqlGeographyBuilder时,"指定的输入不表示有效的地理实例"异常

Question

我编写了一个小应用程序,它从一系列KML文件读入,然后Microsoft.SqlServer.Types.SqlGeography使用以下代码将它们转换为类型:

    private SqlGeography CreateGeographyFromKML( string kml, bool debug )
    {
        // use SqlGeographyBuilder to help create the SqlGeography type 
        var geographyBuilder = new SqlGeographyBuilder();

        // Get co-ordinates 
        var xml = XDocument.Parse(kml);
        var df = xml.Root.Name.Namespace;
        XElement coordinates = xml.Descendants(df + "coordinates").Single();

        // set the Spatial Reference Identifiers that will used to create the point 
        geographyBuilder.SetSrid(_srid);
        geographyBuilder.BeginGeography(OpenGisGeographyType.Polygon);

        var longLat = coordinates.Value.Split(' ').Select(c => new { Lat = Convert.ToDouble(c.Split(',')[1]), Long = Convert.ToDouble(c.Split(',')[0]) });

        Console.Write("Found {0} ", longLat.Count());

        foreach (var coord in longLat.Select((x, i) => new { Index = i, Value = x }))
        {
            if (coord.Index == 0)
            { // First point
                if ( debug ) Console.WriteLine("First point: {0},{1}", coord.Value.Lat, coord.Value.Long);
                geographyBuilder.BeginFigure(coord.Value.Lat, coord.Value.Long);
            }
            else
            { // Intermediate points
                if (debug) Console.WriteLine("Intermediate point: {0},{1}", coord.Value.Lat, coord.Value.Long);
                geographyBuilder.AddLine(coord.Value.Lat, coord.Value.Long);
            }

            if (coord.Index == longLat.Count() - 1 )
            { // Last point (Close polygon)     
                if (debug) Console.Write("Last point: ");

                // Check not already added
                if (longLat.Last().Lat == longLat.First().Lat && longLat.Last().Long == longLat.First().Long)
                {
                    if (debug) Console.Write("Already exists - not adding...");
                }
                else
                {
                    if (debug) Console.Write("{0},{1}", longLat.Last().Lat, longLat.Last().Long);
                    geographyBuilder.AddLine(longLat.Last().Lat, longLat.Last().Long);
                }

                geographyBuilder.EndFigure(); // End figure
            }
        }

        if (debug) Console.WriteLine();

        // close the figure and geography class 
        geographyBuilder.EndGeography();

        // get the geography builder to return the sqlgeography type 
        return geographyBuilder.ConstructedGeography;
    }

基本上,此代码从KML文件中检索Lat/Longs列表,然后循环遍历它们以创建多边形.

但是我导入的一些KML文件失败,出现以下异常:

捕获到System.ArgumentException消息= 24200:指定的输入不表示有效的地理实例.

这发生在以下行: return geographyBuilder.ConstructedGeography;

我发现了一些对这个异常的引用,但是在我发现它们在SQL Server中遇到并处理这个异常而不是C#的情况下.

Answer 1

我有同样的错误,但结果是多边形环定向问题.翻转坐标数组顺序的简单问题解决了这个问题.

为了说明,这失败了以上错误:

 select geography::STGeomFromText ('Polygon  ( (10 10, 10 20, 20 20, 20 10, 10 10))',4326)

这有效:

 select geography::STGeomFromText ('Polygon  ( (10 10, 20 10, 20 20, 10 20, 10 10))',4326)

请注意,我没有在一个点内翻转x,y对,我正在翻转整个点数组的顺序(例如{pt1,pt2,pt3,pt4,pt5}变为{pt5,pt4,pt3,pt2,pt1 }