Category Archives: video

More fun with Triggertrap

I’ve added a couple of timelapses to Youtube this week, both made with Triggertrap here in Edinburgh.

The first is a capture of Bruce Munro’s Field of Light installation currently at St Andrew square. This was my first experiment with the ‘bulb ramping’ approach, of extending the shutter speed as the timelapse progresses to compensate for falling light as the sun sets. It’s a bit rough around the edges due to some technical limitations and having to guess at appropriate settings, but works reasonably well at compressing the hour around sunset into a minute. You can see Field of Light until April 27th.

The second is a collection of timelapses from the construction of a giant mathematical sculpture. Innovative Learning Week at the University of Edinburgh gives students and staff alike a chance to branch out from their usual lecture schedule and try something different, and this event organised by Julia Collins from the School of Mathematics was a UK first. Involving a team of 20 people, nearly 11,000 pieces of zometool, over six hours of construction time and several extra large pizzas, we were able to built a ‘giant 4D buckyball’, or more formally, a cantitruncated 600 cell. You should be able to go and see this at Summerhall until we need the pieces for something else – probably the Edinburgh Science Festival around Easter – and I’ll try to write more about the mathematics over on Modulo Errors in due course.

(For both videos, you may be better off viewing in full HD.)

Space-time manipulation (with buses)

I’ve been continuing my adventures in image manipulation with Matlab, taking the opportunity to play with a technique I’ve been interested in for a long time – ‘slit scan’ or ‘strip’ photography. A very brief (but rather maths-y) explanation of what’s going on in the clip above would be the following:

Let a video be defined by T frames each of dimension X-by-Y. Then the pixel value to be displayed at location x,y at time t is simply V(x,y,t) for some 3-dimensional array V; so the kth frame corresponds to the 2-d image Fk given by the plane T=k. But we may consider other planes to generate frames; by fixing a horizontal position X=k individual frames are images given by (t,y)=V(k,y,t) and iterating through these gives a new video V’(x,y,t)=V(t,y,x).

If that tells you everything you need to know, you can look at a couple more examples here and (more abstractly) here. Otherwise, read on for a fuller explanation!

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RoombaTrap

Having finally dragged myself into the smartphone age I was at last able to get set up with the mobile version of TriggerTrap, a timelapse gizmo created by some friends of mine. I already had a starting project in mind, to capture the antics of my Roomba.

Having recently returned to Edinburgh for an MSc, I find myself studying Matlab for the first time in a decade. I always feel that the best way to familiarise yourself with a programming language is to have a goal in mind, and I remembered from a JMM talk that Matlab can be used for image processing. So whilst I’d normally reach for python to tackle an unfamiliar task, on this occasion I took the rather circuitous route of Matlab, processing and some video-editing tools.

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Photography and the 3rd generation ipad

With my current camera gear filling an entire carry-on bag, a laptop is too much extra bulk/weight, so on my last few trips I’ve been surviving on an ipod touch for limited web browsing, email access and so on. This got me wondering whether a tablet would be a good fit, especially if it gave me the ability to review, back-up and share photos on the move whilst also improving my internet experience and offering video/ebooks for when IFE doesn’t cut it. The launch of the latest ipad, with a screen resolution that puts even my desktop to shame, provided just the extra nudge I needed to explore the idea seriously.

But in researching my options I found myself immediately confronted by a stack of conflicting information regarding what was or wasn’t possible with the ipad. Presumably to encourage uptake of the higher-capacity models, apple don’t include a memory card slot, nor standard USB sockets, on the ipad. Instead there’s an external connection kit, and establishing which permutations of ipad model / iOS version / camera brand / connection type would co-operate was not easy – perhaps not helped by the lack of tech savvy from some users, as many comments on apple’s site strongly suggested PEBCAK. A visit to the store didn’t allow for a practical test as they didn’t have adaptors in stock, but they were willing to accept a return of the ipad if it proved not to be suitable for purpose. Probably knowing that I’d really struggle to give it back after playing for a while, even if some sort of android tablet would be more useful for my needs!

Well, mine arrived yesterday, and I’m pleased to report that for the Canon 550d (T2i) – and presumably their other sd card based models – it all plays together beautifully. But in trying it out, I stumbled into various other seas of online confusion regarding photo handling, so I thought I’d collect together what I’ve learnt so far (admittedly, in all of 24 hours) in the hopes it helps save others some time/effort. This is not a guide to taking photos with the ipad, which still strikes me as a ridiculous idea!

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