On Fenchel-Nielsen Coordinates of Surface Group Representations into SU(3,1)

Let $Sigma_g$ be a compact, connected, orientable surface of genus $g geq 2$. We ask for a parametrization of the discrete, faithful, totally loxodromic representations in the deformation space ${rm Hom}(pi_1(Sigma_g), {rm SU}(3,1))/{rm SU}(3,1)$. We show that such a representation, under some hypothesis, can be determined by $30g-30$ real parameters.