InfraRed (IR) thermography systems are mandatory to ensure safe plasma operation in fusion devices. Developed systems so far consist in monitoring and controlling in real time the power load on the Plasma Facing Components (PFCs) through their surface temperature measurements. However IR measurements are made much more complicated in metallic environment because of the spurious contributions of the reflected fluxes. This paper presents a full predictive photonic simulation able to assess accurately the surface temperature measurement with classical IR thermography from a given plasma scenario and by taking into account the optical properties of PFCs materials. This simulation has been carried out the ITER-like wide angle infrared camera view of JET in comparing with experimental data. The consequences and the effects of the low emissivity and the Bidirectional Reflectivity Distribution Function (BRDF) used in the model for the metallic PFCs on the contribution of the reflected flux in the analysis are discussed.