public class DotDensityRendererDefinition : RendererDefinition 

/// <summary>
/// Renders a polygon feature layer with Dot Density symbols to represent quantities.
/// ![Dot Density renderer](https://ArcGIS.github.io/arcgis-pro-sdk/images/Renderers/dotDensity-renderer.png)
/// </summary>
{
  //Check feature layer name
  //Code works with the USDemographics feature layer available with the ArcGIS Pro SDK Sample data
  var featureLayer = MapView.Active.Map.GetLayersAsFlattenedList().OfType<FeatureLayer>().FirstOrDefault(f => f.Name == "USDemographics");
  if (featureLayer == null)
  {
    MessageBox.Show("This renderer works with the USDemographics feature layer available with the ArcGIS Pro SDK Sample data", "Data missing");
  }
  //Define size of the dot to use for the renderer
  int dotSize = 3;
  //Check if the TOTPOP10 field exists
  int idxField = -1;
  using (var table = featureLayer.GetTable())
  {
    var def = table.GetDefinition();
    idxField = def.FindField("TOTPOP10");
  }
  // "TOTPOP10" field was not found
  if (idxField == -1)
    return;

  //array of fields to be represented in the renderer
  var valueFields = new List<string> { "TOTPOP10" };
  //Note: Run within QueuedTask
  //Create the DotDensityRendererDefinition object
  var dotDensityDef = new DotDensityRendererDefinition(valueFields, colorRamp,
                                                                    dotSize, 30000, "Dot", "people");
  //Create the renderer using the DotDensityRendererDefinition
  CIMDotDensityRenderer dotDensityRndr = (CIMDotDensityRenderer)featureLayer.CreateRenderer(dotDensityDef);

  //if you want to customize the dot symbol for the renderer, create a "DotDensitySymbol" which is an
  //Amalgamation of 3 symbol layers: CIMVectorMarker, CIMSolidFill and CIMSolidStroke
  //Define CIMVectorMarker layer          
  var cimMarker = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.RedRGB, dotSize);
  var dotDensityMarker = cimMarker as CIMVectorMarker;
  //Define the placement
  CIMMarkerPlacementInsidePolygon markerPlacement = new CIMMarkerPlacementInsidePolygon { Randomness = 100, GridType = PlacementGridType.RandomFixedQuantity, Clipping = PlacementClip.RemoveIfCenterOutsideBoundary };
  dotDensityMarker.MarkerPlacement = markerPlacement;

  //Define CIMSolidFill layer
  CIMSolidFill solidFill = new CIMSolidFill { Color = new CIMRGBColor { R = 249, G = 232, B = 189, Alpha = 50 } };

  //Define CIMSolidStroke
  CIMSolidStroke solidStroke = new CIMSolidStroke { Color = ColorFactory.Instance.GreyRGB, Width = .5 };

  //Create the amalgamated CIMPolygonSymbol that includes the 3 layers
  var dotDensitySymbol = new CIMPolygonSymbol
  {
    SymbolLayers = new CIMSymbolLayer[] { dotDensityMarker, solidFill, solidStroke }
  };

  //Apply the dotDensitySymbol to the CIMDotDenstityRenderer's DotDensitySymbol property.
  dotDensityRndr.DotDensitySymbol = dotDensitySymbol.MakeSymbolReference();

  //Apply the renderer to the polygon Feature Layer.
  featureLayer.SetRenderer(dotDensityRndr);
}