Passive /active markers together?

gotoxy
Posts: 27
Joined: Tue Dec 18, 2007 7:56 am
Location: NBG; DE

Re: Passive /active markers together?

Post by gotoxy »

Hi Will,

good luck finishing the suit. I'm very excited to see the pics!

Cheers
Sven
fxrtst
Posts: 61
Joined: Sat Oct 13, 2007 2:55 pm

Re: Passive /active markers together?

Post by fxrtst »

Oh its an ungly sucker, thats for sure...I think this is for sure a prototype..next time I'd like to flush mount the LEDs to the suit..I placed the LEDs about an inch from surface, in hopes to help with occlusion, but think I just created a place for everything to get snagged on. In any event, I will be testing tonight and taking pictures tonight.

Will

PS Is there a was to post pictures to this forum?
VincentG
Posts: 7728
Joined: Mon Jul 17, 2006 5:00 am
Location: Corvallis, Oregon

Re: Passive /active markers together?

Post by VincentG »

Currently not an easy way.....
fxrtst
Posts: 61
Joined: Sat Oct 13, 2007 2:55 pm

Re: Passive /active markers together?

Post by fxrtst »

Well got it together, set up a skeleton and captured. My first thoughts:

1) Alot of popping going on. I would assume that with 6 cameras, I am not getting enough coverage. The reflective balls have larger surface area to capture, the IR LEDs on the other hand have maybe 120 degree angle (if I am lucky). So me thinks with 6 cameras its harder to track.

2)Occlusion, all my wires feeding the LEDs have to be kept flat against the suit.

3) Battery power lasted alot longer than i thought.
gotoxy
Posts: 27
Joined: Tue Dec 18, 2007 7:56 am
Location: NBG; DE

Re: Passive /active markers together?

Post by gotoxy »

Hi Will,

OK, thanks for your input.
Yesterday I was searching again for iR LEDs there are many different kinds. Even smd LEDs with an half angle of over 90 degrees.
I few month ago I testet those parts. It was really a fine mechanics job. But i managed to solder them together to a small cluster of 2 or 3 LEDs.
OK, with that hi LED count on your suit, your battery power would not last very long.
One other option perhaps are LEDs in a plasic package.
I made a test with a 5mm wide angle LEDs in an purple smokey package and found that they even emit enough iR at their bottom side. Probaly due to the deffuseness of the plastic packaging.
An other idea is to give the LEDs a small cap of diffuse plasic. But i did not found a product yet, matching my needs.
(Like tiny tabletennis balls)

Take a look at http://www.farnell.com


Cheers
Sven
fxrtst
Posts: 61
Joined: Sat Oct 13, 2007 2:55 pm

Re: Passive /active markers together?

Post by fxrtst »

Sven,

I had thought about a clear lucite ball, sanded lightly with a 300 grit sand paper as a diffuser for the LED's. The LED's I used, are the LEDs from Natural Points web site, and I believe they are used for the array around the cameras. They have no problem emitting IR the distance to the cameras. Adding a diffuser should still work.

Will

P.S I like the idea of a cluster of LED's but them battery life, is indeed a problem!

If you send me your email I'll send you a few pics of the suit as i don't think I can post here.
jthrush
Posts: 1
Joined: Wed Dec 03, 2008 8:30 pm

Re: Passive /active markers together?

Post by jthrush »

I'm curious as to why you decided to build an active suit? Have you encountered any problems using passive markers?

P.S. We're considering buying an ARENA system soon for our game studio.

Thanks,
James
fxrtst
Posts: 61
Joined: Sat Oct 13, 2007 2:55 pm

Re: Passive /active markers together?

Post by fxrtst »

I have had no problems with passive markers. I had hoped that perhaps I could gain a bit in distance to camera and therefore expanding my capture volume.

Will
gotoxy
Posts: 27
Joined: Tue Dec 18, 2007 7:56 am
Location: NBG; DE

Re: Passive /active markers together?

Post by gotoxy »

Hi Will, I sent you a privat message with may email address.

I just made a test with a new 5mm LED in a smoked package sanded slightly with 240er sand paper. Only tested it with one LED, but it seams to expand the angle enormous. Even far outside the capture volume the most far cam regognizes the signal of the LED nearly completely hidden by the velcro base i glued it on. (reduced the threshold and increased the exposure values of Arena software)
I will order the LEDs today.


@jthrush: ... and with active markers it's not necessary to use the iR-ring of the cameras. Therefore you get no trouble with iR-light of the cameras being reflected on the ground or highlights on other stuff (we have blank matal shelves built up in the room we installed the mocap equipment reflecting the ir light extremely strong)

And you can reduce the threshold value and increase the exposure without getting problems with 'ghost-markers'. And you do not need to block the pixles of the cameras facing each other where you can see the Ir ring of the opposite cam. I expect a gain in sensitivity and resolution.

But nevertheless you get great results with the passive markers. We are very satisfied with the system. And it is alway a big fun to work with it :)


Cheers
Sven
fxrtst
Posts: 61
Joined: Sat Oct 13, 2007 2:55 pm

Re: Passive /active markers together?

Post by fxrtst »

Sven,

Sent.
Post Reply