Value of Vis I(t) = V(D,S,t) Data D transformed by spec S into time-varying image dK/dt = P(I,K) Perception P of image by user increases knowledge K S(t) = S_0 + integral E(K) Interative exploration E changes spec [The Value of Visualization. Jarke van Wijk. Proc. Visualization 2005, www.win.tue.nl/~vanwijk/vov.pdf] 31