protected static boolean isSectorVisible(
      DrawContext dc, Sector sector, double minDistanceSquared, double maxDistanceSquared) {

    View view = dc.getView();
    Position eyePos = view.getEyePosition();
    if (eyePos == null) return false;

    Angle lat = clampAngle(eyePos.getLatitude(), sector.getMinLatitude(), sector.getMaxLatitude());
    Angle lon =
        clampAngle(eyePos.getLongitude(), sector.getMinLongitude(), sector.getMaxLongitude());
    Vec4 p = dc.getGlobe().computePointFromPosition(lat, lon, 0d);
    double distSquared = dc.getView().getEyePoint().distanceToSquared3(p);
    //noinspection RedundantIfStatement
    if (minDistanceSquared > distSquared || maxDistanceSquared < distSquared) return false;

    return true;
  }
    public URL getURL(Tile tile, String altImageFormat) throws MalformedURLException {
      StringBuffer sb;
      if (this.URLTemplate == null) {
        sb = new StringBuffer(WWXML.fixGetMapString(tile.getLevel().getService()));

        if (!sb.toString().toLowerCase().contains("service=wms")) sb.append("service=WMS");
        sb.append("&request=GetMap");
        sb.append("&version=").append(this.wmsVersion);
        sb.append(this.crs);
        sb.append("&layers=").append(this.layerNames);
        sb.append("&styles=").append(this.styleNames != null ? this.styleNames : "");
        sb.append("&transparent=TRUE");
        if (this.backgroundColor != null) sb.append("&bgcolor=").append(this.backgroundColor);

        this.URLTemplate = sb.toString();
      } else {
        sb = new StringBuffer(this.URLTemplate);
      }

      String format = (altImageFormat != null) ? altImageFormat : this.imageFormat;
      if (null != format) sb.append("&format=").append(format);

      sb.append("&width=").append(tile.getWidth());
      sb.append("&height=").append(tile.getHeight());

      Sector s = tile.getSector();
      sb.append("&bbox=");
      sb.append(s.getMinLongitude().getDegrees());
      sb.append(",");
      sb.append(s.getMinLatitude().getDegrees());
      sb.append(",");
      sb.append(s.getMaxLongitude().getDegrees());
      sb.append(",");
      sb.append(s.getMaxLatitude().getDegrees());
      //            sb.append("&"); // terminate the query string

      return new java.net.URL(sb.toString().replace(" ", "%20"));
    }
    protected boolean isNavSectorVisible(
        DrawContext dc, double minDistanceSquared, double maxDistanceSquared) {
      if (!navSector.intersects(dc.getVisibleSector())) return false;

      View view = dc.getView();
      Position eyePos = view.getEyePosition();
      if (eyePos == null) return false;

      // check for eyePos over globe
      if (Double.isNaN(eyePos.getLatitude().getDegrees())
          || Double.isNaN(eyePos.getLongitude().getDegrees())) return false;

      Angle lat =
          clampAngle(eyePos.getLatitude(), navSector.getMinLatitude(), navSector.getMaxLatitude());
      Angle lon =
          clampAngle(
              eyePos.getLongitude(), navSector.getMinLongitude(), navSector.getMaxLongitude());
      Vec4 p = dc.getGlobe().computePointFromPosition(lat, lon, 0d);
      double distSquared = dc.getView().getEyePoint().distanceToSquared3(p);
      //noinspection RedundantIfStatement
      if (minDistanceSquared > distSquared || maxDistanceSquared < distSquared) return false;

      return true;
    }
  private void appendGeoTiff(ArrayList<TiffIFDEntry> ifds, AVList params)
      throws IOException, IllegalArgumentException {
    if (null == params || 0 == params.getEntries().size()) {
      String reason = Logging.getMessage("nullValue.AVListIsNull");
      Logging.logger().finest(Logging.getMessage("GeotiffWriter.GeoKeysMissing", reason));
      return;
    }

    long offset = this.theChannel.position();

    if (params.hasKey(AVKey.DISPLAY_NAME)) {
      String value = params.getStringValue(AVKey.DISPLAY_NAME);
      if (null != value && 0 < value.trim().length()) {
        offset = this.theChannel.position();
        byte[] bytes = value.trim().getBytes();
        this.theChannel.write(ByteBuffer.wrap(bytes));
        ifds.add(new TiffIFDEntry(Tiff.Tag.DOCUMENT_NAME, Tiff.Type.ASCII, bytes.length, offset));
      }
    }

    if (params.hasKey(AVKey.DESCRIPTION)) {
      String value = params.getStringValue(AVKey.DESCRIPTION);
      if (null != value && 0 < value.trim().length()) {
        offset = this.theChannel.position();
        byte[] bytes = value.trim().getBytes();
        this.theChannel.write(ByteBuffer.wrap(bytes));
        ifds.add(
            new TiffIFDEntry(Tiff.Tag.IMAGE_DESCRIPTION, Tiff.Type.ASCII, bytes.length, offset));
      }
    }

    if (params.hasKey(AVKey.VERSION)) {
      String value = params.getStringValue(AVKey.VERSION);
      if (null != value && 0 < value.trim().length()) {
        offset = this.theChannel.position();
        byte[] bytes = value.trim().getBytes();
        this.theChannel.write(ByteBuffer.wrap(bytes));
        ifds.add(
            new TiffIFDEntry(Tiff.Tag.SOFTWARE_VERSION, Tiff.Type.ASCII, bytes.length, offset));
      }
    }

    if (params.hasKey(AVKey.DATE_TIME)) {
      String value = params.getStringValue(AVKey.DATE_TIME);
      if (null != value && 0 < value.trim().length()) {
        offset = this.theChannel.position();
        byte[] bytes = value.getBytes();
        this.theChannel.write(ByteBuffer.wrap(bytes));
        ifds.add(new TiffIFDEntry(Tiff.Tag.DATE_TIME, Tiff.Type.ASCII, bytes.length, offset));
      }
    }

    if (params.hasKey(AVKey.SECTOR)) {
      if (params.hasKey(AVKey.PIXEL_WIDTH) && params.hasKey(AVKey.PIXEL_HEIGHT)) {
        offset = this.theChannel.position();
        double[] values =
            new double[] {
              (Double) params.getValue(AVKey.PIXEL_WIDTH),
              (Double) params.getValue(AVKey.PIXEL_HEIGHT),
              isElevation(params) ? 1d : 0d
            };
        byte[] bytes = this.getBytes(values);
        this.theChannel.write(ByteBuffer.wrap(bytes));
        ifds.add(
            new TiffIFDEntry(
                GeoTiff.Tag.MODEL_PIXELSCALE, Tiff.Type.DOUBLE, values.length, offset));
      }

      if (params.hasKey(AVKey.WIDTH) && params.hasKey(AVKey.HEIGHT)) {
        offset = this.theChannel.position();

        double w = (Integer) params.getValue(AVKey.WIDTH);
        double h = (Integer) params.getValue(AVKey.HEIGHT);

        Sector sec = (Sector) params.getValue(AVKey.SECTOR);

        double[] values =
            new double[] { // i ,  j, k=0, x, y, z=0
              0d,
              0d,
              0d,
              sec.getMinLongitude().degrees,
              sec.getMaxLatitude().degrees,
              0d,
              w - 1,
              0d,
              0d,
              sec.getMaxLongitude().degrees,
              sec.getMaxLatitude().degrees,
              0d,
              w - 1,
              h - 1,
              0d,
              sec.getMaxLongitude().degrees,
              sec.getMinLatitude().degrees,
              0d,
              0d,
              h - 1,
              0d,
              sec.getMinLongitude().degrees,
              sec.getMinLatitude().degrees,
              0d,
            };

        byte[] bytes = this.getBytes(values);
        this.theChannel.write(ByteBuffer.wrap(bytes));
        ifds.add(
            new TiffIFDEntry(GeoTiff.Tag.MODEL_TIEPOINT, Tiff.Type.DOUBLE, values.length, offset));
      }

      // Tiff.Tag.MODEL_TRANSFORMATION excludes Tiff.Tag.MODEL_TIEPOINT & Tiff.Tag.MODEL_PIXELSCALE

      if (params.hasKey(AVKey.MISSING_DATA_SIGNAL)
          || params.hasKey(AVKey.MISSING_DATA_REPLACEMENT)) {
        offset = this.theChannel.position();

        Object nodata =
            params.hasKey(AVKey.MISSING_DATA_SIGNAL)
                ? params.getValue(AVKey.MISSING_DATA_SIGNAL)
                : params.getValue(AVKey.MISSING_DATA_REPLACEMENT);

        String value = "" + nodata + "\0";
        byte[] bytes = value.getBytes();
        this.theChannel.write(ByteBuffer.wrap(bytes));
        ifds.add(new TiffIFDEntry(GeoTiff.Tag.GDAL_NODATA, Tiff.Type.ASCII, bytes.length, offset));
      }

      if (params.hasKey(AVKey.COORDINATE_SYSTEM)) {
        String cs = params.getStringValue(AVKey.COORDINATE_SYSTEM);

        if (AVKey.COORDINATE_SYSTEM_GEOGRAPHIC.equals(cs)) {
          if (isElevation(params)) this.writeGeographicElevationGeoKeys(ifds, params);
          else this.writeGeographicImageGeoKeys(ifds, params);
        } else if (AVKey.COORDINATE_SYSTEM_PROJECTED.equals(cs)) {
          String msg = Logging.getMessage("GeotiffWriter.FeatureNotImplementedd", cs);
          Logging.logger().severe(msg);
          throw new IllegalArgumentException(msg);
          // TODO extract PCS (Projection Coordinate System)
        } else {
          String msg = Logging.getMessage("GeotiffWriter.UnknownCoordinateSystem", cs);
          Logging.logger().severe(msg);
          throw new IllegalArgumentException(msg);
        }
      }
    }
  }