Why doesn't GeometryEngine.Union perform the union?

MarkCammarere

I'm trying to union two valid (polygon) geometries (they both have valid extents and spatial references), but when I do the Union, I get an empty geometry with NaN extent:

Geometry aGeom = GeometryEngine.Union(aGeom1, aGeom2);

The input geometries (aGeom1, aGeom2) are rectangular polygons in the WGS84 spatial reference (WKID = 4326). I've even tried unioning one of the geometries with itself - and I still get an empty geometry. Please help!

JenniferNery

Can you share the input geometries? I'm unable to reproduce with the following code:

<SPAN class="keyword token">var</SPAN> geom1 <SPAN class="operator token">=</SPAN> Esri<SPAN class="punctuation token">.</SPAN>ArcGISRuntime<SPAN class="punctuation token">.</SPAN>Geometry<SPAN class="punctuation token">.</SPAN>Geometry<SPAN class="punctuation token">.</SPAN><SPAN class="token function">FromJson</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token">"{\"rings\":[[[74,27],[83,27],[83,21],[74,21],[74,27]]],\"spatialReference\":{\"wkid\":4326}}"</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">var</SPAN> geom2 <SPAN class="operator token">=</SPAN> Esri<SPAN class="punctuation token">.</SPAN>ArcGISRuntime<SPAN class="punctuation token">.</SPAN>Geometry<SPAN class="punctuation token">.</SPAN>Geometry<SPAN class="punctuation token">.</SPAN><SPAN class="token function">FromJson</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token">"{\"rings\":[[[78,29],[87,29],[87,22],[78,22],[78,29]]],\"spatialReference\":{\"wkid\":4326}}"</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">var</SPAN> geom3 <SPAN class="operator token">=</SPAN> GeometryEngine<SPAN class="punctuation token">.</SPAN><SPAN class="token function">Union</SPAN><SPAN class="punctuation token">(</SPAN>geom1<SPAN class="punctuation token">,</SPAN> geom2<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

I also tried to interactively draw the rectangle and perform the union of those. This will create geometries in the same reference as the map. 

<SPAN class="keyword token">private</SPAN> <SPAN class="keyword token">async</SPAN> <SPAN class="keyword token">void</SPAN> <SPAN class="token function">Button_Click</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">object</SPAN> sender<SPAN class="punctuation token">,</SPAN> RoutedEventArgs e<SPAN class="punctuation token">)</SPAN>
<SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">try</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> geom1 <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">await</SPAN> MyMapView<SPAN class="punctuation token">.</SPAN>SketchEditor<SPAN class="punctuation token">.</SPAN><SPAN class="token function">StartAsync</SPAN><SPAN class="punctuation token">(</SPAN>SketchCreationMode<SPAN class="punctuation token">.</SPAN>Rectangle<SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">false</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> geom2 <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">await</SPAN> MyMapView<SPAN class="punctuation token">.</SPAN>SketchEditor<SPAN class="punctuation token">.</SPAN><SPAN class="token function">StartAsync</SPAN><SPAN class="punctuation token">(</SPAN>SketchCreationMode<SPAN class="punctuation token">.</SPAN>Rectangle<SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">false</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> geom3 <SPAN class="operator token">=</SPAN> GeometryEngine<SPAN class="punctuation token">.</SPAN><SPAN class="token function">Union</SPAN><SPAN class="punctuation token">(</SPAN>geom1<SPAN class="punctuation token">,</SPAN> geom2<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> graphic <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">Graphic</SPAN><SPAN class="punctuation token">(</SPAN>geom3<SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">SimpleFillSymbol</SPAN><SPAN class="punctuation token">(</SPAN>SimpleFillSymbolStyle<SPAN class="punctuation token">.</SPAN>Solid<SPAN class="punctuation token">,</SPAN> Colors<SPAN class="punctuation token">.</SPAN>Blue<SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">null</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> overlay <SPAN class="operator token">=</SPAN> MyMapView<SPAN class="punctuation token">.</SPAN>GraphicsOverlays<SPAN class="punctuation token">[</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; overlay<SPAN class="punctuation token">.</SPAN>Graphics<SPAN class="punctuation token">.</SPAN><SPAN class="token function">Add</SPAN><SPAN class="punctuation token">(</SPAN>graphic<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="punctuation token">}</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">catch</SPAN><SPAN class="punctuation token">(</SPAN>Exception ex<SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; MessageBox<SPAN class="punctuation token">.</SPAN><SPAN class="token function">Show</SPAN><SPAN class="punctuation token">(</SPAN>ex<SPAN class="punctuation token">.</SPAN>Message<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp; <SPAN class="punctuation token">}</SPAN>
<SPAN class="punctuation token">}</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

Can you see if calling GeometryEngine.Simplify to input geometries before calling Union, returns a valid union geometry?