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Here we're going to look at our basic quad view video, and discuss how it was shot, and
how to get the best out it. To get the best picture from YouTube, you may need to switch
to 720 'p' high definition, and view it in full screen mode.
So each video was shot in two takes, each using two Casio ZR200 cameras, one at the
side and one at the end. The filming was done at 240 frames a second, and we've then used
software to synchronise the different clips and put together the finished video, which
replays at 1/8th speed. To get through a whole group of people quickly, we actually run them
backwards and forwards like a relay, and separate out the clips later. You'll probably be able
to spot runners gathered ready in the background in some of our videos, although we do try
to keep them out of shot until it's their turn.
We originally produced composites with just three panes, front rear and side, but found
that a lot of people have differences between their left and right sides, so we settled
on the widescreen format quad view which you see here.
We bring along a set of belts and markers to the video session. The elasticated belt
is worn around the bony top of the pelvis, to show how the hips move, and the side marker
is positioned on the greater trochanter or thigh bone. Inevitably, these sometimes move
out of position during a session, and the belt does sometimes get covered over by baggy
T-shirts, but they're usually good enough to see what's going on. We sometimes also
use knee and ankle markers, which makes it easier to discern fine movements.
It also makes it easier to see how the body is moving if the runner wears a close fitting
vest or T-shirt and shorts, but using the markers means that even if they are wearing
heavier clothing, we can still get a good idea of what's going on.
The software also puts cross-hairs on the videos, centred at the side of the hip, or
the centre of the belt. They're actually positioned at the moment that the runner's toe leaves
the ground, and then move at constant speed, to give you an idea of how much the runner's
hips are rising, falling and twisting as he runs. The lines are also very useful when
you're assessing the lean of the trunk and the tilt of the pelvis.
Along the ground you'll see a line of crosses, which are placed at the centre of the heel
for the rear view, and the big toe for the front view, and we've used blue for the right
foot, and red for the left foot. You'll also see a black line running through them, and
this gives you an idea how of much the feet are crossing over.