code: public void reportMemoryUsage ()
      {
          Map<Tile.Key,BaseTile> base = Maps.newHashMap();
          Set<BaseTile> fringe = Sets.newHashSet();
          Map<Tile.Key,ObjectTile> object = Maps.newHashMap();
          long[] usage = new long[3];
          for (SceneBlock block : _blocks.values()) {
              block.computeMemoryUsage(base, fringe, object, usage);
          }
          log.info("Scene tile memory usage",
              "scene", StringUtil.shortClassName(this),
              "base", base.size() + "->" + (usage[0] / 1024) + "k",
              "fringe", fringe.size() + "->" + (usage[1] / 1024) + "k",
              "obj", object.size() + "->" + (usage[2] / 1024) + "k");
      }
docs: Reports the memory usage of the resolved tiles in the current scene block.