@Override
 protected void write(final LasPointCloud pointCloud, final EndianOutput out) {
   super.write(pointCloud, out);
   out.writeLEDouble(this.gpsTime);
 }
 @Override
 protected void read(final LasPointCloud pointCloud, final ByteBuffer buffer) throws IOException {
   super.read(pointCloud, buffer);
   this.gpsTime = buffer.getDouble();
 }