View Full Version : Re: How to reconstruct the position of the missed markers duringhuman motion capture

David Smith
02-14-2007, 04:00 AM

What is the typical action of the subject that you observe and is partially
missed by the cameras?
How do you know the interpolation is not accurate? If you know it is not
accurate this might imply you have some way of knowing an accurate
characterisation of the true motion.

This is how I might approach the problem--
The computer can only look at the positions of the markers before and after
the gaps and fill in the missing data in some logical way related to this.
If there is some very fast change of position during the gap time the
computer doesn't know this. You may be able to see this by looking at the
raw data and tracking the position of relevant markers close by, and so
knowing that the relative position of the 'missing' marker cannot change
relative to them or changes in a known way, You can therefore write an
equation which will reinstate the missing marker.

What do you think?

Cheers Dave Smith.

----- Original Message -----
From: "Feng"
Sent: Monday, February 12, 2007 4:36 PM
Subject: [BIOMCH-L] How to reconstruct the position of the missed markers
during human motion capture

> Dear colleague,
> The motion-capture systems (such as Vicon, Qualysis, and Motion Analysis,
> etc.) have being widely used in human movement analysis. It could be
> frequently encountered that some markers are missed for several
> consecutive frames during motion capture. Almost all commercial systems
> mentioned above have the function to fill the gap of the missed marker's
> trajectory by using cubic spline or linear interpolation. However, the
> accuracy is not high enough using this function. Sometime, the filled
> trajectory is totally wrong.
> Does any one have same experience to solve this problem? Is there any
> reference which describes the reconstruction of the spatial trajectory of
> the missed marker?
> Any comment will be sincerely appreciated.
> Warm regards
> Feng Yang
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