topic Re: Latitude and Longtitude in ArcGIS Runtime SDK for WPF (Retired) Questions

Latitude and Longtitude

StanleyHo — Thu, 28 Mar 2013 02:21:01 GMT

Hi,

I need to draw polygons on the map but the polygon coordinates is based on latitude and longitude.

How do I convert latitude and longitude from map X and Y coordinate?
How do I do the reverse?

Re: Latitude and Longtitude

DavidMartin — Thu, 28 Mar 2013 10:13:20 GMT

You can use the GeometryService to project between different coordinate systems. The Project tool will also take a datum transformation if needed. See http://resources.arcgis.com/en/help/runtime-wpf/apiref/index.html?ESRI.ArcGIS.Client~ESRI.ArcGIS.Client.Tasks.GeometryService~Project.html

Re: Latitude and Longtitude

StanleyHo — Sat, 11 Dec 2021 09:09:54 GMT

Thanks for the reply.

I am having trouble understanding GeometryService that you mention. i can't seems to find the latitude, longitude conversion and vice versa.

However, from the samples, I discover that it plots the polygon based on latitude and longitude.

Here is the code:

string polyCoordinate = "2.5,-1 2.5,1 -2.5,1 -2.5,-1 2.5,-1";
ESRI.ArcGIS.Client.Geometry.PointCollectionConverter pointConverter = new ESRI.ArcGIS.Client.Geometry.PointCollectionConverter();
ESRI.ArcGIS.Client.Geometry.PointCollection pointCollection = pointConverter.ConvertFromString(polyCoordinate) as ESRI.ArcGIS.Client.Geometry.PointCollection;

//setup the polygon
Polygon aoi = new Polygon();
aoi.Rings.Add(pointCollection);

BrushConverter brushConv = new BrushConverter();
SimpleFillSymbol symbol = new SimpleFillSymbol();
symbol.BorderBrush = brushConv.ConvertFromString(areaData.Color) as SolidColorBrush;
symbol.BorderThickness = 1;
symbol.Fill = brushConv.ConvertFromString(areaData.FillColor) as SolidColorBrush;

ESRI.ArcGIS.Client.Projection.WebMercator mercator = new ESRI.ArcGIS.Client.Projection.WebMercator();
Graphic polygon = new Graphic();
polygon.Geometry = mercator.FromGeographic(aoi);
polygon.Symbol = symbol;
graphicsLayer.Graphics.Add(polygon);

Each point is based on latitude and longitude value.
However, I got a problem. Firstly, my web will be cached map (downloaded periodically and use offline) and not downloaded realtime.
Is WebMercator still usable?
If WebCator isn't usable, can show me an example on how to convert map point to latitude and longitude and vice versa?

Thanks

Re: Latitude and Longtitude

MichaelBranscomb — Tue, 02 Apr 2013 06:45:50 GMT

Hi,

If you're translating between WGS1984 and Web Mercator Auxiliary Sphere there is a WebMercator class to support this very common case: http://resources.arcgis.com/en/help/runtime-wpf/apiref/index.html?ESRI.ArcGIS.Client~ESRI.ArcGIS.Client.Projection.WebMercator_members.html.

Otherwise - for the greatest flexibility you should look at http://resources.arcgis.com/en/help/runtime-wpf/apiref/index.html?ESRI.ArcGIS.Client~ESRI.ArcGIS.Client.Geometry.CoordinateConversion_members.html.

Cheers

Mike

Re: Latitude and Longtitude

StanleyHo — Wed, 03 Apr 2013 06:51:46 GMT

Thanks for the reply.

I got a question if the cached map (in WebMercator format) is downloaded from the web?
When I take the cache map offline, can I still use the webMercator class to transalte between WGS1984 and webmercator and vice versa?

Re: Latitude and Longtitude

MichaelBranscomb — Wed, 03 Apr 2013 07:16:33 GMT

Hi,

Yes the WebMercator class is part of the API and therefore will remain alongside your application if it goes "offline". You can also use the LocalGeometryService offline, if you're using the Standard license level.

To use cached maps offline you'll need to create a Tile Package, or take a copy/extract of the server-side cache.

Cheers

Mike

Re: Latitude and Longtitude

StanleyHo — Fri, 05 Apr 2013 05:38:14 GMT

Thanks. I will look into the LocalGeometryService.