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Van Den Bogert, Ton
12-12-2007, 08:37 AM
Dan,

I assume this was meant as a private communication, not for public distribution.

It may be good for Oshri to clarify this in a follow up post, though. It would be useful for people to know how to interface with Vicon if they want to avoid delays.

Ton
(Biomch-L moderator)


> -----Original Message-----
> From: Dan India / Qualisys NA [mailto:dan.india@qualisys.com]
> Sent: Wednesday, December 12, 2007 3:46 PM
> To: 'Oshri Even-Zohar'; BIOMCH-L@NIC.SURFNET.NL
> Subject: RE: [BIOMCH-L] Using Real-Time VICON with MATLAB
>
> Oshri:
>
> Your system is extremely unique and has capabilities to
> integrate passive and active mocap technology and with huge
> successes and benefits. We are all aware of minimal, fixed
> processing delays in passive marker systems and its
> technology but as identified in the previous Emails, Vicon
> has a 10 - 50 ms variable delay in producing its 3D file.
> Whereas, you are not experiencing it.
>
> Are you (eMotek) using the raw 2D data straight from Vicon's
> camera into your proprietary (eMotek's) 3D tracker for your
> 3D solutions or does eMotek use the Vicon supplied 3D
> tracker? That might explain the difference between your
> findings (no delay) and others in seeing the as stated delays.
>
> Its uncommon for the same technology with the same features
> to produce different outcomes.
>
>
> Dan India
>
> Qualisys North America
> Daniel India, MS MBA, VP Medical Sciences
> 9301 Monroe Road Suit B
> Charlotte, NC 28270
>
> T: 847-945-1411
> C: 847-778-4949
> F: 651-453-9676
>
> Dan.India@Qualisys.Com
> WWW.Qualisys.Com
>
>
>
>
>
> -----Original Message-----
> From: * Biomechanics and Movement Science listserver
> [mailto:BIOMCH-L@NIC.SURFNET.NL] On Behalf Of Oshri Even-Zohar
> Sent: Wednesday, December 12, 2007 12:54 PM
> To: BIOMCH-L@NIC.SURFNET.NL
> Subject: Re: [BIOMCH-L] Using Real-Time VICON with MATLAB
>
> Hi Ravi.
> The CAREN software from MOTEK MEDICAL (www.motekmedical.com)
> has Custom Vicon drivers that get raw data from Vicon and do
> not suffer from the delay you mentiond. have a look Good
> luck Oshri Even Zohar
>
> ________________________________
>
> From: * Biomechanics and Movement Science listserver on
> behalf of Philippe Archambault, Dr.
> Sent: Wed 12/12/2007 15:45
> To: BIOMCH-L@NIC.SURFNET.NL
> Subject: Re: [BIOMCH-L] Using Real-Time VICON with MATLAB
>
>
>
> Ravi,
>
> I am also looking at possible solutions on how to use a
> motion capture system in real time. I see two potential
> pitfalls with a real time system combining Vicon and Matlab
> xPC. The first is that Vicon communicates its data through
> TCP/IP, however, xPC can only use UDP; TCP/IP is not possible
> and this has been confirmed by a Mathworks software engineer.
>
> The other problem is that Vicon introduces a delay of 10-50
> ms (depending on your setup) between actual, physical
> movement and the time that this data is communicated to the
> target computer. For my needs, this delay is much too high.
> Personally, I believe that an active marker system is more
> appropriate for real time.
>
> Hope this helps,
>
> Philippe
>
> Philippe Archambault, OT, PhD
> Assistant professor
> School of Physical & Occupational Therapy, McGill University
> 3654 Promenade Sir-William-Osler
> Montreal QC H3G 1Y5
> T: (+1) 514 398-7323
> F: (+1) 514 398-6360
> W: www.mcgill.ca/spot
>
>
> On Dec 10, 2007 7:42 AM, Raviraj Nataraj
> wrote:
>
> > Hello, Biomech-L,
> >
> > Our lab has recently upgraded its VICON motion capture
> system, which
> > now includes real-time data capture. We are looking to use
> real-time
> > marker data for controller feedback. The controller will be under
> > real-time operation using the xPC-Target software toolkit within
> > MATLAB. Thus, we ultimately need to link the real-time data stream
> > from VICON to a "target" computer. If anyone has had
> experience with
> > this or something similar, any advice on how best to
> proceed would be
> greatly appreciated.
> >
> > Sincerely,
> > Ravi Nataraj
> > PhD Student, BME Department, Case Western Reserve University Motion
> > Study Lab, Cleveland Stokes VAMC
> >
>
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