The Kuramoto-Sivishinsky model describes the dynamics of a cellular fl
ame front. It has been known for some time that on scales large compar
ed with the size of a cell the front appears to be a self-affine fract
al which has noisy dynamics in 1+1 dimensions. We use the inverse meth
od of Lam and Sander (Phys. Rev. Lett. 71, 561 (1993)) to show explici
tly how the scaling occurs and how deterministic chaos at small scales
develops into noisy dynamics at large scales, and how a small scale p
attern becomes a large scale disordered fractal via an intermediate sc
aling regime.