public LASStretchType StretchType {get; set;}

{
  var elevLasStretchRendererDef = new LasStretchRendererDefinition(ArcGIS.Core.CIM.LASStretchAttribute.Elevation);
  // accept the defaults for color ramp, etc

  if (lasDatasetLayer.CanCreateRenderer(elevLasStretchRendererDef))
  {
    CIMTinRenderer renderer = lasDatasetLayer.CreateRenderer(elevLasStretchRendererDef);
    if (lasDatasetLayer.CanSetRenderer(renderer, SurfaceRendererTarget.Points))
      lasDatasetLayer.SetRenderer(renderer, SurfaceRendererTarget.Points);
  }
  // OR use a stretch renderer with stretchType standard Deviations
  var elevLasStretchStdDevRendererDef = new LasStretchRendererDefinition(ArcGIS.Core.CIM.LASStretchAttribute.Elevation);
  elevLasStretchStdDevRendererDef.StretchType = LASStretchType.StandardDeviations;
  elevLasStretchStdDevRendererDef.NumberOfStandardDeviations = 2;
  // accept the defaults for color ramp,  etc
  // Note: Needs QueuedTask to run
  {
    if (lasDatasetLayer.CanCreateRenderer(elevLasStretchStdDevRendererDef))
    {
      CIMTinRenderer renderer = lasDatasetLayer.CreateRenderer(elevLasStretchStdDevRendererDef);
      if (lasDatasetLayer.CanSetRenderer(renderer, SurfaceRendererTarget.Points))
        lasDatasetLayer.SetRenderer(renderer, SurfaceRendererTarget.Points);
    }
  }
}