The large area quantitative visualisation method of air streams.

The project is aimed to develop the quantitative method of visualization of the air steams in application to the indoor problems of heauilg , ventilating and air conditioning. The geometrically well defined light sheet is crossing the examined space and determines the plane of observation. The photographic camera is placed perpendicularly to this plane at a distance of a few meters. The flow is seeded with the soap bubbles of the diameter 3-4 mm. The light is reflected from those bubbles which are crossing the illuminating sheet. The film is exposed in the concerned areas: the trajectories of the tracer are recorded in form of alongated tracks. The photographic images contain the features of the flow which are revealed and quantified in the digitizing operations. The images existing on the colour slides are splitted into six equal square parts and digitized once for each colour with a camera having a 512x512 pixel sensor. The grey scale levels are so adapted that the black slide area obtain the value zero (or any other but small one) in the digital representation matrix. With either Roberts or Sobel operators edges of the bubble tracks (having any orientation) are detected and enhanced. The above steps are the basis for extracting the velocity vector field from the experimental images.