how to detecte local features on a 3D mesh

Hi, I have this function that i have got from the toolbox that Tal Darom has devloped to compute local features for meshes:

    function [ detectedPts, scale ] = dog(  vertex, faces, num_octaves, params )
if ~exist('params','var')
    params = [];
end
if ~isfield(params,'sigscale')
    params.sigscale = 0;
end
if ~isfield(params,'ExcludeBoundery')
    params.ExcludeBoundery = 0;
end
%dog find geometry difference of gaussians features  
    ss = size(vertex);
    if (ss(1) == 3)
        vertex = vertex';
    end    
%create ocataves
    %W = my_euclidean_distance(triangulation2adjacency(faces),vertex);
    W = triangulation2adjacency(faces);
    W = W + speye(length(vertex));

the problem is that i can not understand how can I passe vertices, faces and params, I have tested with the number of vertices of the mesh and his number of faces also but i didn't succeed. I have an .obj file format containing my mesh. I would be greatful for your help.