On the linear combination of the Gaussian and student’s t random field and the integral geometry of its excursion sets

In this paper, a random field, denoted by GTβν, is defined from the linear combination of two independent random fields, one is a Gaussian random field and the second is a student’s t random field with ν degrees of freedom scaled by β. The goal is to give the analytical expressions of the expected Euler–Poincaré characteristic of the GTβν excursion sets on a compact subset S of R2. The motivation comes from the need to model the topography of 3D rough surfaces represented by a 3D map of correlated and randomly distributed heights with respect to a GTβν random field. The analytical and empirical Euler–Poincaré characteristics are compared in order to test the GTβν model on the real surface.