def METHOD_NAME(cls, params, md, x=0, y=0, roiHalfSize=5):
    """Evaluate the model that this factory fits - given metadata and fitted parameters.
    Used for fit visualisation"""
    #generate grid to evaluate function on
    vx, vy, _ = md.voxelsize_nm
    X = vx*np.mgrid[(x - roiHalfSize):(x + roiHalfSize + 1)]
    Y = vy*np.mgrid[(y - roiHalfSize):(y + roiHalfSize + 1)]
    return (f_gaussAstigSlow(params, X, Y), X[0], Y[0], 0)