+/* Update a root tile */
+/* Based on eye distance (lat,lon,elev) */
+void gis_tile_update(GisTile *root,
+ gdouble res, gint width, gint height,
+ gdouble lat, gdouble lon, gdouble elev,
+ GisTileLoadFunc load_func, gpointer user_data);
+
+/* Find the leaf tile containing lat-lon */
+GisTile *gis_tile_find(GisTile *root, gdouble lat, gdouble lon);
+
+/* Delete nodes that haven't been accessed since atime */
+GisTile *gis_tile_gc(GisTile *root, time_t atime,
+ GisTileFreeFunc free_func, gpointer user_data);
+