  The progress of image processing during recent years allows the measurement
of pedestrian characteristics on a "microscopic" scale with low costs. However,
density and flow are concepts of fluid mechanics defined for the limit of
infinitely many particles. Standard methods of measuring these quantities
locally (e.g. counting heads within a rectangle) suffer from large data
scatter. The remedy of averaging over large spaces or long times reduces the
possible resolution and inhibits the gain obtained by the new technologies.
  In this contribution we introduce a concept for measuring microscopic
characteristics on the basis of pedestrian trajectories. Assigning a personal
space to every pedestrian via a Voronoi diagram reduces the density scatter.
Similarly, calculating direction and speed from position differences between
times with identical phases of movement gives low-scatter sequences for speed
and direction. Closing we discuss the methods to obtain reliable values for
derived quantities and new possibilities of in depth analysis of experiments.
The resolution obtained indicates the limits of stationary state theory.
