/// <summary>
 ///     Adds a single extended POI marker characteristics as fields.
 /// </summary>
 /// <param name="field"></param>
 /// <returns></returns>
 public IMapImageBuilder AddMarker(PoiField field)
 {
     _mapImage.poix.Add(field.ToString());
     return(this);
 }
 /// <summary>
 ///     Adds a single extended POI marker characteristics as fields.
 /// </summary>
 /// <param name="field"></param>
 /// <returns></returns>
 public IMapImageBuilder AddMarker(PoiField field)
 {
     _mapImage.poix.Add(field.ToString());
     return this;
 }