We demonstrate an interactive software system in which the emissivity of wafers can be estimated in situ using different models. The system allows the data taker to introduce a choice of design parameters necessary for the control of temperature uniformity. The objective of the interactive system is to obtain a better estimation of the wavelength dependent emissivity by using existing data such as integrated emissivity, for example, as input information. Results for some of the models are presented and compared to show differences in the models chosen. The principle advantage offered by the system are the likely prospects of a realistic improvement and confident assessment for real time temperature measurement and control in an RTP environment.