Select features in 3D view

Question

I got the following error when I was trying to select features using a geometry from a SketchTool.

var pFeatures = pActiveView.GetFeatures(pGeometry);

"3D views only support selecting features interactively using geometry in screen coordinates relative to the top-left corner of the view."

I changed SketchOutputMode from Map to Screen.  I had the same error.  Any ideas?

Wolf · Answer

Sorry, I guess I should have tried this first. It would have been my preferred implementation. It appears that when you use SketchOutputMode = SketchOutputMode.Screen the OnSketchCompleteAsync geometry parameter has a null spatial reference (hence the exception you get). Most API functions actually allow you to directly use this 'screen spatial referenced' geometry, but if you want to get a MapPoint, Line, Polygone etc. you need to use the MapView.Active.ClientToMap method to convert to a useful geometry. So the short answer can be found in this snippet: protected async override Task<bool> OnSketchCompleteAsync(Geometry geometry) { if (geometry.SpatialReference == null) { // screen coordinates var screenPointAsMapPoint = geometry as MapPoint; if (screenPointAsMapPoint != null) { var pnt = new System.Windows.Point { X = screenPointAsMapPoint.X, Y = screenPointAsMapPoint.Y}; var mapScreenPoint = await QueuedTask.Run<MapPoint>( () => MapView.Active.ClientToMap(pnt)); _graphic = await this.AddOverlayAsync(mapScreenPoint, _pointSymbol.MakeSymbolReference()); } } }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ For the long answer I tried the sample snippet below by creating a tool called MapToolScreenToMap. This tool uses the screen coordinates (points only) and converts the Point to a MapPoint using the current Map's spatial reference. I tried both 2D and 3D, both seem to work. internal class MapToolScreenToMap : MapTool { private CIMPointSymbol _pointSymbol = null; private IDisposable _graphic = null; public MapToolScreenToMap() { IsSketchTool = true; SketchType = SketchGeometryType.Point; SketchOutputMode = SketchOutputMode.Screen; } protected async override Task OnToolActivateAsync(bool active) { if (_pointSymbol == null) _pointSymbol = await CreatePointSymbolAsync(); } protected async override Task<bool> OnSketchCompleteAsync(Geometry geometry) { if (geometry.SpatialReference == null) { // screen coordinates var screenPointAsMapPoint = geometry as MapPoint; if (screenPointAsMapPoint != null) { var mapScreenPoint = await QueuedTask.Run<MapPoint>( () => MapView.Active.ClientToMap(new System.Windows.Point { X=screenPointAsMapPoint.X, Y =screenPointAsMapPoint.Y})); _graphic = await this.AddOverlayAsync(mapScreenPoint, _pointSymbol.MakeSymbolReference()); } } else { // map coordinates _graphic = await this.AddOverlayAsync(geometry, _pointSymbol.MakeSymbolReference()); } return true; } protected override Task OnToolDeactivateAsync(bool hasMapViewChanged) { if (_graphic != null) _graphic.Dispose();//Clear out the old overlay _graphic = null; return base.OnToolDeactivateAsync(hasMapViewChanged); } internal static Task<CIMPointSymbol> CreatePointSymbolAsync() { return QueuedTask.Run(() => SymbolFactory.Instance.ConstructPointSymbol(ColorFactory.Instance.RedRGB, 14, SimpleMarkerStyle.Circle)); } }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

FayuLai · Answer

Hi Wolfgang,

That is really an idea.  I tried to implement this in my program and I got the following error:

System.ArgumentNullException: Value cannot be null.

Parameter name: Spatial reference is null.

The spatial reference of screen geometry is empty.  That may cause the exception.  But how to create a screen geometry with valid spatial reference?

Best regards,

Fayu

Wolf · Answer

Hi Fayu, You can use the following snippet to project your geometry to your Map's spatial reference: var mapGeom = GeometryEngine.Instance.Project(screenGeometry, MapView.Active.Map.SpatialReference);‍‍‍