我使用sharpmap从MSSQL渲染边框(几何)作为PNG图像.
这一切都运作良好,除了国家在平面图像格式上看起来太“宽”.

据我了解,我需要创建EPSG转换：3857投影,但我不知道该怎么做.

这是我的代码

 var map = new Map(new Size(request.Width, request.Height));
 map.BackColor = Color.Transparent;
 var countryGeometry = GeometryFromWKT.Parse(dto.CountryWkt);

 IProvider countryProvider = new GeometryFeatureProvider(countryGeometry);
 var countryLayer = new VectorLayer("country", countryProvider);
 var borderColor = System.Drawing.ColorTranslator.FromHtml("#525252");

 countryLayer.Style.EnableOutline = true;
 countryLayer.Style.Outline = new Pen(borderColor);
 countryLayer.Style.Fill = Brushes.Transparent;
 //does not work with this
countryLayer.CoordinateTransformation = new
                ProjNet.CoordinateSystems.Transformations.CoordinateTransformationFactory().CreateFromCoordinateSystems(
                    ProjNet.CoordinateSystems.GeographicCoordinateSystem.WGS84,
                    ProjNet.CoordinateSystems.ProjectedCoordinateSystem.WebMercator);

 map.Layers.Add(countryLayer);

 map.ZoomToBox(new Envelope(dto.Envelope.BottomLeft.Longitude,
            dto.Envelope.TopRight.Longitude,
            dto.Envelope.BottomLeft.Latitude,
            dto.Envelope.TopRight.Latitude
        ));

 var img = map.GetMap();

WKT可以在这里找到https://pastebin.com/PEbpAdxT

任何帮助表示赞赏.

编辑：
这是我现在为法国和它的区域“Limousin”得到的图像.正如你所看到的,它太“宽”了.

这是我应用转换时的图像,可以在代码注释下找到它不适用于此

编辑2

我也试过跟踪转换,但这会呈现空白png(没有红色交叉)

 public  ICoordinateTransformation Wgs84toGoogleMercator
        {
            get
            {

                if (_wgs84ToGoogle == null)
                {
                    CoordinateSystemFactory csFac = new ProjNet.CoordinateSystems.CoordinateSystemFactory();
                    CoordinateTransformationFactory ctFac = new CoordinateTransformationFactory();

                    IGeographicCoordinateSystem wgs84 = csFac.CreateGeographicCoordinateSystem(
                      "WGS 84", AngularUnit.Degrees, HorizontalDatum.WGS84, PrimeMeridian.Greenwich,
                      new AxisInfo("north", AxisOrientationEnum.North), new AxisInfo("east", AxisOrientationEnum.East));

                  // var a =  csFac.CreateFromWkt("aa");


                    List<ProjectionParameter> parameters = new List<ProjectionParameter>();
                    parameters.Add(new ProjectionParameter("semi_major", 6378137.0));
                    parameters.Add(new ProjectionParameter("semi_minor", 6378137.0));
                    parameters.Add(new ProjectionParameter("latitude_of_origin", 0.0));
                    parameters.Add(new ProjectionParameter("central_meridian", 0.0));
                    parameters.Add(new ProjectionParameter("scale_factor", 1.0));
                    parameters.Add(new ProjectionParameter("false_easting", 0.0));
                    parameters.Add(new ProjectionParameter("false_northing", 0.0));
                    IProjection projection = csFac.CreateProjection("Google Mercator", "mercator_1sp", parameters);

                    IProjectedCoordinateSystem epsg900913 = csFac.CreateProjectedCoordinateSystem(
                      "Google Mercator", wgs84, projection, LinearUnit.Metre, new AxisInfo("East", AxisOrientationEnum.East),
                      new AxisInfo("North", AxisOrientationEnum.North));

                    ((CoordinateSystem)epsg900913).DefaultEnvelope = new [] { -20037508.342789, -20037508.342789, 20037508.342789, 20037508.342789 };

                    _wgs84ToGoogle = ctFac.CreateFromCoordinateSystems(wgs84, epsg900913);
                }

                return _wgs84ToGoogle;

            }
        }

解决方法:

您使用的CoordinateTransformation实际上有效.

由于ZoomToBox坐标错误,您将获得空白图像,因此它实际上显示了图像的空白部分.如果你使用map.ZoomToExtents();相反,要在缩放之前查看整个图像,它看起来像这样：

现在,如果我在浏览器中手动缩放以获得应用此转换的法国特写图像,您可以看到它实际上不再被拉伸.

作为结论,我要说你只需要修复你的ZoomToBox坐标,一切都会正常工作.希望能帮助到你.