this is for holding javascript data
Paul St-Aubin renamed Methodology - Video Data.tex to Methodology Video Data.tex
almost 10 years ago
Commit id: dba6d05b468cb85be809836185fe4b8137d5ce90
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\subsection{Video Data}
\subsubsection{Trajectories: Positions in Space and Time (x,y,t)}
Trajectories are, at the simplest level, a series of points in cartesian space representing the position of (the center of) a moving object at time $t$ on a planar syrface (height $z$ is ignored). Points are evenly spaced in time with a consistent $\delta t$ equivalent to the inverse of the framerate of the video. Typical framerates for video are between 15 to 30 frames per second, or 15 to 30 observations per moving object per second, after feature grouping. The object itself is represented by a mass of charicteristic features closely spaced and moving in unison.
\subsubsection{Derived Measures: Velocity & Acceleration}
Velocity and acceleration are derived from position over time and velocity over time respectively. These are vectors with a magnitude (speed) and a heading. The heading of the velocity vector is typically used to determine the orientation of the vehicle.
It should be noted that velocities and accelerations are smoothed over a window of 5 to ten frames. As such, acceleration measures can be problematic to measure.
\subsubsection{Size of data (hours, GB, framerate, resolution)}
