[GIS] How to draw line/multiline, polygon/multipolygon with SharpMap from Coordinate Source

cjsonpolygon-creationsharpmapvb.net

I have a list of n points, exactly x objects in GeoJSON from a CouchDB. I want to generate lines/multilines and polygons/mutipolygons with
SharpMap and add this to a Layer in VB.NET. For points its easy, but for the rest: I don't get it. Must I use ICoordinateSequence?

So, can anybody post here some example to generate such geometries dynamically from coord-list-like text- or GeoJSON/JSON-Sources (maybe here its another workaround than for plain text?), much detail as possible.

Best Answer

You could look at: var jsonSerializer = new NetTopologySuite.IO.GeoJsonSerializer(); jsonSerializer.Deserialize(...)

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[GIS] How to draw a polygon with preset length in OpenLayers

The standard way to add a regular polygon to an OpenLayers map is with the createRegularPolygon method.

Here's an example:

var lat = 40.12345
var lon = -90.54321
var center_point = new OpenLayers.Geometry.Point(lon, lat);
var triangle = new OpenLayers.Geometry.Polygon.createRegularPolygon(center_point, 1.2, 3, 90);

In this example the lon/lat values are in degrees (e.g., EPSG:4326), and the radius (1.2) is in those map units as well.

EDIT: If you want a circle instead of a triangle, change the "sides" parameter (3 in the example above) to 20, which gives a good approximation of a circle.

[GIS] How to use Sharpmap to display spatial data from MS SQL Server 2008

You need to specify an object id column! If you don't have one on your table, you need to add one (UINT).

You need to check your connection string. Is your SQL-Server instance really "YOUSSEF-PC\SQL"?
You can test if your connection works by invoking

System.Diagonstics.Debug.Assert(vly.GetFeatureCount() > 0);

Do you have geometry of geography objects in your table? If they are not geometry, you need to specify that in the constructor like

VectorLayer vly= new VectorLayer("vly", new SharpMap.Data.Providers.SqlServer2008(connstr, "quartier", "shape", "oid", SqlServerSpatialObjectType.Geography));

Best Answer

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[GIS] How to draw a polygon with preset length in OpenLayers

[GIS] How to use Sharpmap to display spatial data from MS SQL Server 2008

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