Description
Accurate angular quadratures are crucial for the numerical solution of three-dimensional (3D) radiative transfer problems, especially when including the spectral line polarisation produced by the scattering of anisotropic radiation. There are two requirements for an optimal quadrature that are difficult to satisfy simultaneously: high accuracy and short computing time. Recently, imposing certain symmetries, we have derived a set of near optimal angular quadratures. Here we extend our previous investigation by considering other symmetries. Moreover, we test the performance of our new quadratures by numerically solving a radiative transfer problem of resonance line polarisation in a 3D model of the solar atmosphere resulting from a magneto-hydrodynamical simulation. The new angular quadratures derived here outperform the previous ones in terms of the number of rays needed to achieve any given accuracy.
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