public bool ModulateUsingIntensity {get; set;}

{
  var lasPointsReturnsRendererDef = new LasUniqueValueRendererDefinition(LasAttributeType.ReturnNumber);
  lasPointsReturnsRendererDef.ModulateUsingIntensity = true;
  lasPointsReturnsRendererDef.SymbolScaleFactor = 1.0;
  // accept the defaults for color ramp, symbolTemplate
  // Note: Needs QueuedTask to run
  {
    if (lasDatasetLayer.CanCreateRenderer(lasPointsReturnsRendererDef))
    {
      CIMTinRenderer renderer = lasDatasetLayer.CreateRenderer(lasPointsReturnsRendererDef);
      if (lasDatasetLayer.CanSetRenderer(renderer, SurfaceRendererTarget.Points))
        lasDatasetLayer.SetRenderer(renderer, SurfaceRendererTarget.Points);
    }
  }
}