Effective visualization of stereo particle image velocimetry vector fields of a turbulent boundary layer

Stereo particle image velocimetry datasets contain three-dimensional information over a plane, from which multiple quantities can be derived at each point. The task of visualizing these different parameters simultaneously is challenging, and this inhibits our ability to analyse and derive firm conclusions about the physics of the flow. Currently, the common approach is to view each parameter separately in different images. Such an approach is very inefficient, especially for large fields of view where many important structures and features co-exist. In this paper we discuss several ways in which the primary quantities can be viewed simultaneously in the same image. The simplest method is to use different colours for each parameter and to overlay all the different colours on one image. The limitations of such an approach will be described. Other methods considered involve using texture generated from a line integral convolution algorithm to convey instantaneous velocity direction and magnitude. Animated texture is also described, together with variants involving combined colour and out-of-plane height. The use of height in tandem with colour and animated texture is a useful method in distinguishing the different parameters in the regions of overlap.