Nothing prevents you from pushing a byte into a ByteBuffer.
I will try to reduce the memory footprint of my whole application before trying to use on disk buffers.
As said, the OS manages the memory for you, there is no need to worry about it.
The data sets will be too big to fit into a single buffer. The file in input occupies about 250 MB but the meshes in output might occupy tens of GB (Paris metropolitan region in 3D). MappedByteBuffer uses a direct NIO buffer under the hood, it means that I will have to destroy it by myself if the Java heap is not stressed enough, it's a known problem but I'm even not sure such a buffer could be allocated in some cases. I have found several things to optimize in Ardor3D:http://www.ardor3d.com/forums/viewtopic.php?f=10&t=5905#p16504
I have to map only a part of the data into physical memory at a time and to avoid trying to get a backing array or the whole content of the buffer.