  We address the effect of disorder geometry on the critical force in
disordered elastic systems. We focus on the model system of a long-range
elastic line driven in a random landscape. In the collective pinning regime, we
compute the critical force perturbatively. Not only our expression for the
critical force confirms previous results on its scaling with respect to the
microscopic disorder parameters, it also provides its precise dependence on the
disorder geometry (represented by the disorder two-point correlation function).
Our results are successfully compared to the results of numerical simulations
for random field and random bond disorders.
