Difference in bufferGeodetic and SimpleMarkerSceneSymbol

VineetMenon

Hi,

 

I'm creating a circle (buffer operation with geodesic) and a sphere (SimpleMarkerSceneSymbol) from the same center and with the same radius. But I'm getting different results in both cases.

 

Any idea why?

 

Relevant code follows,

 

GraphicsOverlay layer = new GraphicsOverlay();
Point centerPoint = new Point(78, 22, SpatialReferences.getWgs84());
int radius = 1;
LinearUnit km = new LinearUnit(LinearUnitId.KILOMETERS);
SimpleLineSymbol simpleLineSymbol = new SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, 0xFF00FF00, 3);
SimpleFillSymbol simpleFillSymbol = new SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, 0x11FF0000, simpleLineSymbol);
Polygon polygon = GeometryEngine.bufferGeodetic(centerPoint, radius, km, Double.NaN, GeodeticCurveType.GEODESIC);
Graphic rangeGraphic2D = new Graphic(polygon, simpleFillSymbol);
layer.getGraphics().add(rangeGraphic2D);

SimpleMarkerSceneSymbol redSphereSymbol = new SimpleMarkerSceneSymbol(SimpleMarkerSceneSymbol.Style.SPHERE, 0x77FF0000, radius * 1000,
radius * 1000, radius * 1000, SceneSymbol.AnchorPosition.CENTER);
Graphic rangeBalloon3D = new Graphic(centerPoint, redSphereSymbol);

// add the graphic to the graphics overlay 
layer.getGraphics().add(rangeBalloon3D);

mapView.getGraphicsOverlays().add(layer);

 

MarkBaird

Hi @VineetMenon 

When you are creating a SimpleMarkerScene symbol (which can be a cone, tetrahedron, tube etc) you create it by specifying the height, width and height.  The difference you are seeing with your geodesic buffer can be explained because you are working with a radius from a point effectively.

I fixed your code by setting the size of the symbol dimensions to twice the radius of your buffer.  Note that because you are working in 3D with a SimpleMarkerSceneSymbol, the shape you end up with is a geodetic albeit slightly generalised.  

 

 

      // the size needs to be 2 times the radius of the buffer
      SimpleMarkerSceneSymbol redSphereSymbol = new SimpleMarkerSceneSymbol(SimpleMarkerSceneSymbol.Style.SPHERE, 0x77FF0000, radius * 2000,
          radius * 2000, radius * 2000, SceneSymbol.AnchorPosition.CENTER);
      Graphic rangeBalloon3D = new Graphic(centerPoint, redSphereSymbol);

 

 

This is the result with the corrected dimensions:

Does this help?