Three years

Ah yes, and so it has come, the email. When you embark on a PhD there is an initial flurry of interest on the part of the university, mainly to ensure you have paid all your fees, filled out your scholarship forms, and been told how to sit correctly in your office chair. They spend a bit of time explaining how this whole PhD thing works, drag in some senior students to tell you all about it, and then, nothing. You're on your own. Apart from the fortnightly bank statement telling you your scholarship payment has arrived, and an annual letter informing you that according to the university's records, you are indeed still a university student, that's about it. No "hi, how's it goin'?", or "what have you been up to?" emails. Not even a Christmas card. Nothing. Then, three years down the track, after all the trials and tribulations, journal club meetings, conferences, lab visits, seminars, pub sessions and introductory yoga classes, an email arrives.

Dear Chris,
remember us. We're the Australian National University and your time is nearly up! If you're a slack arse student who won't be finished in time, fill out this form to beg for our mercy.

yours,
ANU
ps. merry Christmas


You see, in theory, a PhD is supposed to take three years. There is a legend often told at the Uni house pub on Friday's, and in the tea rooms of many a research lab, that once upon a time, somewhere, a PhD thesis was submitted in three years. No one knows his or her name, or what the topic was, but I suspect they studied at The University of Fairy Land, where supervisors have inifinite time to talk with you, trained monkeys run your experiments, and ready to submit PhD theses grow on trees. The fact is, despite the university's admirable attempts to put some curry in the PhD sauce, and get students to complete quickly, very few achieve this. Why is this you ask ?

Well, for those not familiar with the wonderous world of the PhD degree, let me explain. A PhD in its classical form, has little to do with lectures, exams, lab classes, semesters, prescribed text books and to be honest, anything else you probably attribute with a university undergrad degree. It is a student, a desk, and the none too small task of coming up with something that prior to your work, was not known, designed, created or explained before. You do get some help though. A supervisor for one, who can be quite useful, although less effective as you progress and realise after a couple of years that you know more about your topic than they do (this is expected by the way). You also have hundreds of papers, articles and other forms of media that provide a seemingly endless supply of material that may or may not be related to what you're doing. Of course, the relevance and accuracy of this material varies, and so a significant amount of time is spent trying to sift through and find papers of use to you, while at the same time hoping not to find something so useful as to render your own work obsolete. It can be as frightening as it is enlightening.

The summary of all of this is that tangible outcomes can be few and far between, and in general, the structureless nature of the degree means much of the motivation to get work done, work that is often highly brain intensive and not particularly enticing on a Friday afternoon (or any afternoon for that matter), must come from within. Of course, choosing an interesting topic to begin with definitely helps this. Although, this is also akin to choosing a song you really like, and playing it over, and over, and over again ... for four years. Sometimes you just wish you could skip to the next track.

This probably all sounds very negative, but it is somewhat ironic that the one thing that causes much of the stress and pain associated with a PhD, is also the one huge motivator to keep going with it ... intellectual freedom. An academic once told me that he really envied his PhD students, and yearned for the time he spent as a PhD student (admittedly it had probably been at least twenty years since he completed his, giving him ample time to forget the pain). What he missed most was the opportunity a PhD offered to emerse himself so thoroughly, and without obstruction, in an intellectual interest. To spend day upon day researching a topic that genuinely excited him, with a real purpose, was a luxury he had not experienced to the same degree since. I remember telling myself I should talk to this guy more often - I hadn't felt this motivated since getting my pen license.

So three years in, and I am happy to say that I am still pretty excited about the work I am doing. Equally though, I have never been more motivated to get on with things, and get this thesis out the door. Like the vast majority of those before me, I will be applying for an extension, otherwise I would have to pull out the most productive February on record. I'm motivated, but not that motivated.

In any case, it's nice to hear from the University after all these years. I look forward to hearing from them again. Probably in 6 months time.

Words a PhD student never wants to hear

interesting work .. I used to work with someone who I think looked at a very similar problem to this.

Oh really .. When was that?

1983

Time flies when you're out of your depth

I have just finished what I think I can safely say has been my hardest PhD day to date. I'll admit, I didn't necessarily start the day in the right frame of mind, courtesy of last night's A-League soccer final viewing at All Bar Nun transforming from an intended 2 pint, home by 8pm evening to a 6 pint, home by 1am affair. It was a good night though. Today, unfortunately, needed every brain cell I could muster.

It's not like anything disastrous happened, or even anything particularly bad. It was just one of those days where I felt completely out of my depth. This is perhaps something that those of you who dabble in the fine art of mathematics every now and then may relate to. You have a problem to solve, and you know there is a nice solution, but you realise that the required knowledge for obtaining that solution goes well beyond your own expertise.

At first you think, ok, wikepedia time, as you try to cram a semester's worth of differential geometry into a couple of hours. Of course you soon realise that this is not working, and you are more confused than ever, which leads you to the next natural step - ask the supervisor. I did this at approximately 2pm this afternoon. I have just returned to my desk - it's 7.40pm! The scary thing is that I thought it was about 5pm! I was supposed to play netball at 6.50pm.

Unfortunately, despite all the time spent on my problem, I am still feeling well out of my depth. This is compounded by the fact that I only have a few weeks left to write the paper that this work will be included in, and so have little time to get my head around some pretty advanced topics. I actually feel a bit sick when I think about what needs to be done.

In any case, today is very much over, and I am thankfully off home. All of this research bullshit is very much tomorrow's problem now.

"Belco" kitchen goes live

It must surely be a good sign for the year ahead when the very first email I read on January 1, in a hung over state in Carlton, was a message informing me that a paper I submitted back in September, has been accepted for publication and presentation at this years ICRA(International Conference on Robotics and Automation). This conference is the biggest robot geeks gathering of them all, and attracts a fair bit of interest, so I am pretty happy about making the cut.

Apart from the obvious research benefits of getting more runs on the board, this particular achievement is made more significant in that the conference is in Rome this year. Having a paper to present while in Italy is very good for me (and avoids any possibility of my travel funding being suddenly taken away, not that I really feared that would happen). One slightly tricky thing is that the conference is about a week after Aff and I get married, so the honeymoon will happen straight after I give my talk (which will undoubtedly be in the last session of the last day, as per usual).

Another interesting fact about this paper is that this will be the first to feature Aff and my kitchen (referred to in the paper as the "belco" kitchen sequence). While working at home one day, with my fancy wide-angle lens camera, I walked it around our kitchen to construct an image sequence for one of my major results (though I wasn't really thinking I'd use it at the time). As it turns out, our kitchen is perfect for feature and motion detection, which is really just a nice (and slightly geeky) way of saying it's a bit of a mess.

So for your viewing pleasure (sorry Aff), I present ... the "belco" kitchen sequence.

The nitty gritty
The line you see moving around like a compass is actually indicating the estimated direction of forward motion. I use the visual motion of the scene as the camera moves along, to try and estimate which direction I am moving in. This is tricky because you can only extract this sort of information from the visual motion due to the camera's straight line motion, and so I first have to remove any motion due to the camera's rotation. Of course, I have no information other than what I see in these images to work with, so I can't just say "I know I rotated by this much, so deduct that from the visual motion". I have to estimate everything.

The blue and yellow dots around the circle indicate the direction in which the visual motion is going at that point in the image (blue is clock-wise, yellow is anti-clockwise). This information helps me "de-rotate" the visual motion.

Being a world-wide accessible blog, I should make it clear that much of what I have described above is based on some theoretical work that was done in the late eighties by Nelson and Aloimonos. As far as I know, the belco kicthen sequence is the first demonstration of this technique being used in real-time, on real image sequences. I am amazed this technique wasn't taken further a lot earlier than this.

Once I know which direction I am going, and I have removed the rotation, I can then build what are known as depth maps from the remaining visual motion. This is essentially a map showing what space is free and what is obstructed around the camera (which has a 190 degree field of view). I do this by exploiting the fact that things that are closer appear to move faster than things further way (just like bees). This is obviously pretty useful for navigating around unknown environments.

The paper's details:
"Real time biologically-inspired depth maps from spherical flow", by C. McCarthy, N. Barnes and M.V. Srinivasan. To appear in proceedings of IEEE ICRA 2007. Rome, Italy, April 10-13, 2007.