public TinSurfaceType SurfaceType {get;}

{
  var constraintCount = lasDataset.GetSurfaceConstraintCount();
  IReadOnlyList<ArcGIS.Core.Data.Analyst3D.SurfaceConstraint> constraints = lasDataset.GetSurfaceConstraints();
  foreach (var constraint in constraints)
  {
    var dsName = constraint.DataSourceName;
    var wksPath = constraint.WorkspacePath;
    var heightField = constraint.HeightField;
    var surfaceType = constraint.SurfaceType;
  }
}