public void updateAt(Tile tile) {
    int value = 0 ;
    final Element owner = tile.owner() ;
    
    if (owner instanceof Installation) {
      value = ((Installation) owner).structure().ambienceVal() ;
    }
    if (owner instanceof Flora) {
      value = ((Flora) owner).growStage() ;
    }
    for (Mobile m : tile.inside()) if (m instanceof Actor) {
      final Actor a = (Actor) m ;
      value -= 5 * a.health.stressPenalty() ;
      final Item outfit = a.gear.outfitEquipped() ;
      if (outfit != null) value += (outfit.quality - 1) / 2f ;
    }
    
    mapValues.set((byte) value, tile.x, tile.y) ;
  }