Abstract
If an ionizing particle passes through a super heated liquid boiling can take place on the ions created by the particle. These vapour bubbles are photographed under flash illumination and show up the track of the particle. By using two or more cameras the original space position of the track is calculated from measurements made on the different views. The present total rate of production of such photographs in the various high energy physics laboratories throughout the world is about ten million photographs per year. The various methods, in use today, for processing all this information are described and some comments made about possible future development.