diff --git a/prjxray/overlay.py b/prjxray/overlay.py
index 2ba4b779..95ef8e38 100644
--- a/prjxray/overlay.py
+++ b/prjxray/overlay.py
@@ -1,3 +1,13 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2017-2020  The Project X-Ray Authors.
+#
+# Use of this source code is governed by a ISC-style
+# license that can be found in the LICENSE file or at
+# https://opensource.org/licenses/ISC
+#
+# SPDX-License-Identifier: ISC
 class Overlay(object):
     """ Object that represents an overlay.
 
@@ -5,8 +15,8 @@ class Overlay(object):
 
     """
 
-    def __init__(self, db, region_dict):
-        self.grid = db.grid()
+    def __init__(self, grid, region_dict):
+        self.grid = grid
         self.region_dict = region_dict
 
     def tile_in_roi(self, grid_loc):
@@ -18,43 +28,3 @@ class Overlay(object):
             if x1 <= x and x <= x2 and y1 <= y and y <= y2:
                 return False
         return True
-
-    def gen_tiles(self, tile_types=None):
-        ''' Yield tile names within overlay.
-
-        tile_types: list of tile types to keep, or None for all
-        '''
-
-        for tile_name in self.grid.tiles():
-            loc = self.grid.loc_of_tilename(tile_name)
-
-            if not self.tile_in_roi(loc):
-                continue
-
-            gridinfo = self.grid.gridinfo_at_loc(loc)
-
-            if tile_types is not None and gridinfo.tile_type not in tile_types:
-                continue
-
-            yield tile_name
-
-    def gen_sites(self, site_types=None):
-        ''' Yield (tile_name, site_name, site_type) within overlay.
-
-        site_types: list of site types to keep, or None for all
-
-        '''
-
-        for tile_name in self.grid.tiles():
-            loc = self.grid.loc_of_tilename(tile_name)
-
-            if not self.tile_in_roi(loc):
-                continue
-
-            gridinfo = self.grid.gridinfo_at_loc(loc)
-
-            for site_name, site_type in gridinfo.sites.items():
-                if site_types is not None and site_type not in site_types:
-                    continue
-
-                yield (tile_name, site_name, site_type)