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Japanese Garden in Freiburg, Black Forest by carsten_t_rees.

Digital Media Bursary - Dry Run

Yesterday I spent all day at the Phoenix centre doing a dry run for the installation, to check that it would definitely all work etc.

First up was testing different projection methods.
Front projection would have given a brighter image and allowed more space, but caused problems with people's shadows falling on the screen as I couldn't get the projector close enough and high enough.
Back projection meant losing half the room, but totally eliminated shadow problems. Unfortunately the relatively thick screen meant that the projected image alone wasn't enough for the video camera to pick up people's movement...

Front projection diagram, copied from the previous blog entry:

Camera Position
The ideal position for the motion capture camera (a normal DV camera connected via Firewire) would be directly overhead. Limited places in the ceiling for attaching it mean that it can either go in the middle of the room or above the screen.

So the rear-projection setup ended up looking like this:

There's a nice side-effect - with this layout the camera picks up the doorway into the room, meaning that the view starts changing as soon as someone walks in to the room, as seen in this overhead plan view:

Plus a couple of shots of the camera. In the first, you can just about see a Manfrotto superclamp and ball head supporting the camera.

In the second you can see the ceiling of the room. For the rear projection setup the screen is hung below the lighting rail, cutting the room in half.

Projection Choice
On balance, I've gone with the back projection setup.
1. No shadows.
2. More intimate, tidier space - one corner of the room had recently been used a filming set and was covered in white tiles. Some drapes down the sides of the screen hide all of that, along with the computer and projector.
3. Immediate reaction to people entering room.
4. Image quality - the rear projection screen softens the image slightly. As people are going up quite close to the image this means that it isn't pixellating in the same way that the front projected image was.

Other problems

The camera and projector need to be quite a long way apart, and the computer (an old G5 PowerMac) is quite heavy so can't easily go high up. So, we need a long Firewire cable from the computer to the DV camera.
Right, I've got a 5m FW cable, problem solved! Well, it would be if it wasn't a 6-pin to 6-pin cable being plugged into a 4-pin port on the camera...
A lot of tramping around assorted electrical shops in Exeter looking for a 6-to-4-pin FW adapter didn't find one, not too surprising as they are pretty rare. I could order online, but tht doesn't help me do full trial run.
But... as of Saturday 24th November, Exeter has an Apple Store! Exeter may be the county capital, but it's still only 117 thousand people. Yet it got the first Apple Store in SW England, and about the sixth in the whole of the UK. Not that I'm complaining...

Anyway, they didn't have one either. But what they did have (apart from huge crowds of people) was a dinky little bus-powered FW hub. Noticeably more expensive than the adapter would have been (in fact, more expensive than a new 6-4 5m cable), it has the big advantage of acting as a FW repeater, meaning that I could use the 5m 6-6 cable AND the 1.5m 6-4 pin cable that was with the camera. This gave a total of 6.5m without exceeding the recommended 5m cable length for the FW400 specification.

Camera View:
The DV camera has a relatively wide FoV for for a video camera, but compared to what most panoramic photographers are used to it's woefully inadequate. This meant that the area covered for the motion capture was a bit... limited. I was already aware of this, and had bought along the 0.7 adapter lens from my old Canon G3 compact, expecting to bodge together something with tape and/or rubber bands. Only they weren't required - when I took off the lens hood, the camera turned out to have a 58mm filter thread, the same size as the thread on the adapter lens. Very handy, and you can see it in the first of the photos above.

Shockwave Xtras:
I'm not the most experienced of programmers when it comes to Shockwave, so it took me awhile to grab all the required Xtras so that it would work on the PowerMac, not just on the notebook where it had been developed.
There was also some kind of problem copying files. I made a new folder, copied the Director projector, media files, Xtras and Spi-V file into it. Copy to the PowerMac. Projector loads, SpiV loads, panoramas don't. Strange.
Double-check that it works in the original folder? Check.
Double-check the path to the SPi-V XML file? Check.
Double-check the paths in the XML file? Check.
Chuck everything into a folder called 'dswmedia' (a security measure needed for some Director stuff), does it work then? No.
Duplicate the whole original folder including loads of different Director projects etc. Does it work now? Check.
Delete all the files that shouldn't be needed. Does it work? Check.
Compare old non-working folder and new working folder. Any visible differences? No.
Oh well, it works, I can't be bothered to find out what the problem was.

The Results
The dry run was in the end a success. Very gratifying after what has turned out to be a long and involved project. Here's a couple of video clips to show you how the installation reacts to movement, one exposed for the projection, one a bit brighter to see the rest of the room. QT7 required, click on the thumbnails to see the videos, 4.4MB & 2.8MB. Oh, ignore the concentric circles, that's just some left over stuff on the wall...

Finally, if you're in the area feel free to drop in next week and see the installation. It'll be running from Thursday lunchtime to Friday evening.


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Re: Digital Media Bursary - Dry Run

Those circles aren't your halo? :-P

Very cool Ian!

Patrick Cheatham
CheathamLane | spinControl:VR
Berkeley, California
VR Photography
Web, Flash & QuickTime Development


Re: Digital Media Bursary - Dry Run

I saw this installation!!!
I am impressed with Ian's work.
Good luck.

Karol Kwiatek


Re: Digital Media Bursary - Dry Run

Very impressive. You brought digital media up-to-date.


Re: Digital Media Bursary - Dry Run

I swear can't believe that I'm actually reading now an article about right projections for taking pictures. Now I can study to project my subject in a right way. I wish to have the good quality for my pictures. Thank you for this article.
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