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Panning

Dear Jim,
John Probe, director of technical support for Ariel Dynamics has used
the panning and he was involved in the implementation of the panning
software module, and he could answer your questions. He provided the
technical training of panning for me when I was in California.
I have been using my Hi 8 camcorder for the panning unit and an
panasonic VHS AG195 camera for the stationary camera view. I manually
panned the Hi8 for the high jumping and hurdler using a fluid tripod
head. There is on the market a Sony camera used in distance education
which will automatically track and pan/tilt on the subject, but I
have not had the money to purchase one for the lab yet.My cameras are
about 20 meters from the plane of movement anbd the panning cube
setup is about 20 ft long with a cube on each end and about 50
control points are visible. But only 6-12 pts per cube are necessary
and I have about 6-8 pts on the panning pole.  The distances between
the known markers are used in calculating the positions of the
cameras in 3D space and then the DLT is transforming the coordinate
information. Typically a 30 degree separation is needed  when using
the 2 stationary camera DLT but I am not sure what the requirements
are for the Ariel panning module. I would suggest that you email Dr.
Ariel about these questions.  Also, you have to make sure that you
have a trial/subject indicator in teh field of view for all cameras
in order to make sure you are using the same trial and I use a camera
strobe that is discharged in the views for the field/frame
synchronization. If you play with the size of a mask over the strobe
you'll be able to see the flash in just one field and the auto iris
will not start adjusting for the brighter light.
Let me now if I can provide any other information.
Al Finch

Hi Jim,
I am using the Ariel APAS panning software for the panning of high
jumping, hurdling and long jumping. In the background I have 2
calibrations cubes that have a pvc pole with markers along it to be
able to calculate the degree of pan. The PVC pole is in sections such
that I can have a 6,12, 18 ft separation. By having this flexibility
I have calibration point information for at least 6 points (18 pts
are available)per cube plus 5-10 points on the poles.The system then
calcualte the panning using the 3D DLTit determine the camera
position. I am presently working on a project comparing the panning
and standard 2 camera fixed 3D DLT and comparing the accuracy during
high jumping.
I hope this gives you some ideas, please feel free to contact me if
you have any other questions.
Sincerely,
Al Finch, Ph.D.
Director Biomechanics Lab
Indiana State University

Hello Normand,

The only difference with the panning camera is the requirement for two
calibration structures.  The left and right calibration structures should
encompass the area that will be used for the analysis.  Each structure
should have a minimum of 8 conrol points (though 14 or more are
recommended), with all points measured relative to a single origin.

The calibration for each camera is handled independently.  Therefore, if
the stationary camera only "sees" the left or the right cube, you will
experience errors as the subject moves out of the calibrated space.  The
same concept hold true for one or more cameras only viewing 1 calibration
structure.

The recommended use of the panning option is that the panning camera see
both cubes.  The stationary cameras should see at least some points on BOTH
calibration structures, though seeing all the points on both structures is
ideal.  When the stationary cameras only see one calibration structure, you
are losing the depth of the calibrated area and errors will increase as the
subject moves out of the calibrated space.  Any number of stationary
cameras can be used in combination with the panning.

I hope this information is helpful.  Please contact us for any additional
information.

Sincerely,

John Probe
Email:  ARIEL1@ix.netcom.com


At 11:27 AM 06/16/2000 -0400, you wrote:
>Dear John/Gideon,
>
>We're trying to master the panning technique and we're facing a few
>problems. We've already gone through all the documention on panning. Here
>are a few questions that should help us find our way around:
>
>1) For the stationnary cams, is there any pre-requisite with regard to the
>calibration. More specifically, is it necessary that each stationnary cam
>sees both calibration structures? or can the right cam sees only the right
>calib frame and left cam, only the left frame?
>
>2) Can we have more than 1 stationnary cam/view per calibration structure
>(e.g., 2 stationnary cams for the right and 2 stationnary cams for the left
>frame and one (or 2) panning cameras?
>
>Thanks in advance,
>
>Normand
>
>
>
>
>Normand Teasdale (Normand.Teasdale@kin.msp.ulaval.ca)
>Universit´┐Ż Laval, Laboratoire de performance motrice humaine, PEPS
>Facult´┐Ż de m´┐Żdecine
>D´┐Żpartement de m´┐Żdecine sociale et pr´┐Żventive
>division de Kin´┐Żsiologie
>Qu´┐Żbec, Qu´┐Żbec G1K 7P4
>T´┐Żl: (418) 656-2147
>Fax: (418) 656-2441
>

 

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