The inverse method analysis provide a quantitative estimation of the force network inside a granular media made in a photoelastic material. With such analysis the contact forces magnitude and orientation can be determined under some assumptions. The main idea of inverse method is to generate a numerical photoelastic picture that matches the experimental one, like illustrated below (from [1]).
>JK: if we want to use this in a new paper we might need to either get permission from RSI to reprint or just do a new version of the image
