  The aim of our study is to detect balance disorders and a tendency towards
the falls in the elderly, knowing gait parameters. In this paper we present a
new tool for gait analysis based on markerless human motion capture, from
camera feeds. The system introduced here, recovers the 3D positions of several
key points of the human body while walking. Foreground segmentation, an
articulated body model and particle filtering are basic elements of our
approach. No dynamic model is used thus this system can be described as generic
and simple to implement. A modified particle filtering algorithm, which we call
Interval Particle Filtering, is used to reorganise and search through the
model's configurations search space in a deterministic optimal way. This
algorithm was able to perform human movement tracking with success. Results
from the treatment of a single cam feeds are shown and compared to results
obtained using a marker based human motion capture system.
