  The radiative transfer equation is a fundamental equation in transport theory
and applications, which is a 5-dimensional PDE in the stationary one-velocity
case, leading to great difficulties in numerical simulation. To tackle this
bottleneck, we first use the discrete ordinate technique to discretize the
scattering term, an integral with respect to the angular variables, resulting
in a semi-discrete hyperbolic system. Then, we make the spatial discretization
by means of the discontinuous Galerkin (DG) method combined with the sparse
grid method. The final linear system is solved by the block Gauss-Seidal
iteration method. The computational complexity and error analysis are developed
in detail, which show the new method is more efficient than the original
discrete ordinate DG method. A series of numerical results are performed to
validate the convergence behavior and effectiveness of the proposed method.
