@Test
  public void testFilenameCreation() throws Exception {
    final ACEElevationModel dem = getElevationModel();

    assertEquals("45S004W.ACE", dem.createTileFilename(-45, -4));
    assertEquals("45S004E.ACE", dem.createTileFilename(-45, +4));
    assertEquals("45N004W.ACE", dem.createTileFilename(+45, -4));
    assertEquals("45N004E.ACE", dem.createTileFilename(+45, +4));

    assertEquals("05S045W.ACE", dem.createTileFilename(-5, -45));
    assertEquals("05S045E.ACE", dem.createTileFilename(-5, +45));
    assertEquals("05N045W.ACE", dem.createTileFilename(+5, -45));
    assertEquals("05N045E.ACE", dem.createTileFilename(+5, +45));

    assertEquals("90S180W.ACE", dem.createTileFilename(-90, -180));
    assertEquals("90S180E.ACE", dem.createTileFilename(-90, +180));
    assertEquals("90N180W.ACE", dem.createTileFilename(+90, -180));
    assertEquals("90N180E.ACE", dem.createTileFilename(+90, +180));
  }