As shown in the fig.10, fig.11 and fig.12, with the wood combustion similar in the initial stage of combustion, the wood doesn’t give the fire and only generates a small bit of smoke. There is almost no difference between the fig.7 and the fig.8. In the middle stage of combustion the cotton send out light and the amount of smoke increase obvious. Analyzing the fig.10,
the fig.11 and the fig.12, the optical flows of before and after the polyurethane combustion are calculated (see table4). The change of the optical flows of cotton is more obvious than the wood’s in the initial stage of combustion. As shown in the fig.13 in the middle stage of combustion the optical flow increases to about 0.83.