extern int otb_6s_waltbrdf_(
  otb_6s_doublereal *a,
  otb_6s_doublereal *ap,
  otb_6s_doublereal *b,
  otb_6s_doublereal *c__,
  otb_6s_integer *mu,
  otb_6s_integer *np,
  otb_6s_doublereal *rm,
  otb_6s_doublereal *rp,
  otb_6s_doublereal *brdfint
  );
