In 2003 the German Research Foundation established a new priority programme on the subject of “Imaging Measurement Methods for Flow Analysis” (SPP 1147). This research programme was based on the fact that experimental ?ow analysis, in addition to theory and numerics, has always played a predominant part both in ?ow research and in other areas of industrial practice. At the time, however, c- parisons with numerical tools (such as Computational Fluid Dynamics), which were increasingly used in research and practical applications, soon made it clear that there are relatively few experimental procedures which can keep up with state-of-the-art numerical methods in respect of their informative value, e.g. with regard to visu- spatial analysis or the dynamics of ?ow ?elds. The priority programme “Imaging Measurement Methods for Flow Analysis” was to help close this development gap. Hence the project was to focus on the investigation of ef?cient measurement me- ods to analyse complex spatial ?ow ?elds. Speci?c cooperations with computer sciences and especially measurement physics were to advance ?ow measurement techniques to a widely renowned key technology, exceeding the classical ?elds of ?uid mechanics by a long chalk.