message: Fix elevation to be absolute.
diff: @@ -158,7 +158,7 @@ class PlanProjectionTreeReference extends PrimaryTreeReference {
  } else if (this._curTransform.elevation !== elevation) {
  const transform = tree.iModelTransform.clone();
  if (undefined !== elevation)
  - transform.origin.z += elevation;
  + transform.origin.z = elevation;
  this._curTransform.transform = transform;
  this._curTransform.elevation = elevation;
  