From the beginning of Computer Graphics various models intended to describe the optical properties of different materials have been proposed. Some of these models are purely empirical [1]. Others are very close to physics but they have a large computational overhead [2,3]. In this paper we introduce a new model for the representation of different materials in photorealistic rendering which is based on the microfacet approach and tailored to ray tracing. The proposed ideas are based on an

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... n developed by Hall and Greenberg [4]. The proposed model fills the gap between existing very primitive and highly sophisticated models, and because it is fast to compute and easy to understand it is not only interesting for scientists but also for practical purposes in industry. At the end of this paper several step by step improvements are described which will be integrated in the proposed equation in the near future