[Beowulf] Re: What now? (Glen Gardner)

dajelen at att.net dajelen at att.net
Fri Aug 20 09:02:04 PDT 2004


Hi Glen,

Thanks for the input.
I do appreciate your position on this and taking the time to respond to my question.

Can you recommend book(s) that you've used that explain image processing that could
get me started with the algorithms?  I assume that there are "better" undergraduate
books on remote sensing and image processing?
My background has been in business (data) processing, rather than numeric (image)
processing.  I consider myself a good programmer who learns quickly.
Is this something I can learn from the book(s)?

I'm not looking to incur the wrath of whomever, just want to learn image processing and
parallel programming . . .

Thanks again,
Dave
-------------- Original message from Glen Gardner : -------------- 
It looks like you hit the thread just fine.

By "simple imaging software", I mean low-level image processing. It typically involves very simple computational tasks, like lowpass filters, highpass filters , based on convolution masks. These kind of tasks are easily parallelized and the filters can usually be written by most people in a few hours.
In any case, I have a number of rather simple filters writtien in C for MPI.  I then call the filters in combination using a shell script to do more complex things. In this way I can use a suite of simple, generic tools in a highly configurable fashion to perfrom more complex imaging tasks in a wider variety of situations than I could with a highly specialized (and more complex) program.

By "embarrassingly parallel" I mean the parallel programs consist of processes which communicate with each other very little (or not at all).
In the case of my imaging software , it only communicates twice. First to divide the imaging data into separate jobs for each node, and once more after processing, to gather and reassemble the "finished" data into an image.

MPI and PVM are publicly available parallel environments. They provide a means of communicating between processes.  If you install one of them on a Linux or FreeBSD cluster you can use it with the compilers that came with the operating system.  From there, you pretty much have to write your own parallel programs.

The software which I have written is not a GPL release, and and it is not public domain.  I have no plans to release it at this time. But such code is a very simple thing to write and sufficient information about the basics of image processing can be found in most undergraduate textbooks on remote sensing and image processing.

I feel a need to justify my position on this, so please bear with me.

There is a general reluctance, on the part of many people (myself included), to publicly release parallel code due to; the unfortunate federal restrictions on the export of high performance computing technology, the high dollar value of good  parallel code, and the high rate of plagiarism in the programming industry. Also, the highly customized nature of Beowulf machines makes it difficult (or impossible) to be sure that a given parallel program will compile and run from one Beowulf  to the next. Overall, the situation discourages public releases of parallel code, and is an unhappy impediment to the sharing of new ideas among high performance computing advocates.  

A lot of people are working to improve the situation, and hopefully there will eventually be a platform for making official releases of parallel code that serves to protect the author's rights as well as making more software available to the public, without upsetting ITAR, homeland security, etc..


Glen


dajelen at att.net wrote:

Hi all,

I receive this maillist as a digest and I wasn't sure how to reply to this thread.

I've been eagerly following this thread of what to do with a Beowulf once it is assembled.

Glen mentioned imaging software that is very simple and embarassingly simple.

Is anything proprietary about this software?
I'd like to learn more about how it works, what it can do, and how to install/run
it on a Beowulf cluster.

This is one of the possibilities I've been considering for a Beowulf cluster and would like
to learn from someone who has already accomplished it.

Thanks,
Dave

P.S.  To all of you, I really do appreciate the input about books and classes that you have
provided.

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-- 
Glen E. Gardner, Jr.
AA8C
AMSAT MEMBER 10593



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