diff --git a/src/java/com/threerings/media/tile/BaseSizableTileSet.java b/src/java/com/threerings/media/tile/BaseSizableTileSet.java
new file mode 100644
index 00000000..5c9fb171
--- /dev/null
+++ b/src/java/com/threerings/media/tile/BaseSizableTileSet.java
@@ -0,0 +1,35 @@
+//
+// Nenya library - tools for developing networked games
+// Copyright (C) 2002-2010 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/nenya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.media.tile;
+
+public interface BaseSizableTileSet
+{
+
+    /**
+     * Returns the base width for the specified object index.
+     */
+    public abstract int getBaseWidth (int tileIdx);
+
+    /**
+     * Returns the base height for the specified object index.
+     */
+    public abstract int getBaseHeight (int tileIdx);
+
+}
\ No newline at end of file
diff --git a/src/java/com/threerings/media/tile/ObjectTileSet.java b/src/java/com/threerings/media/tile/ObjectTileSet.java
index 9138d6e8..89e0fee9 100644
--- a/src/java/com/threerings/media/tile/ObjectTileSet.java
+++ b/src/java/com/threerings/media/tile/ObjectTileSet.java
@@ -33,7 +33,7 @@ import com.threerings.media.image.Colorization;
  * @see ObjectTile
  */
 public class ObjectTileSet extends SwissArmyTileSet
-    implements RecolorableTileSet
+    implements RecolorableTileSet, BaseSizableTileSet
 {
     /** A constraint prefix indicating that the object must have empty space in
      * the suffixed direction (N, E, S, or W). */
@@ -193,16 +193,16 @@ public class ObjectTileSet extends SwissArmyTileSet
         return _zations;
     }
 
-    /**
-     * Returns the base width for the specified object index.
+    /* (non-Javadoc)
+     * @see com.threerings.media.tile.BaseSizableTileSet#getBaseWidth(int)
      */
     public int getBaseWidth (int tileIdx)
     {
         return _owidths[tileIdx];
     }
 
-    /**
-     * Returns the base height for the specified object index.
+    /* (non-Javadoc)
+     * @see com.threerings.media.tile.BaseSizableTileSet#getBaseHeight(int)
      */
     public int getBaseHeight (int tileIdx)
     {
diff --git a/src/java/com/threerings/media/tile/TrimmedObjectTileSet.java b/src/java/com/threerings/media/tile/TrimmedObjectTileSet.java
index a61507e5..ccc2f053 100644
--- a/src/java/com/threerings/media/tile/TrimmedObjectTileSet.java
+++ b/src/java/com/threerings/media/tile/TrimmedObjectTileSet.java
@@ -43,7 +43,7 @@ import com.threerings.media.tile.util.TileSetTrimmer;
  * memory efficient).
  */
 public class TrimmedObjectTileSet extends TileSet
-    implements RecolorableTileSet
+    implements RecolorableTileSet, BaseSizableTileSet
 {
     @Override
     public int getTileCount ()