A video clip shows the computation results of qP, qS1 (fast) and qS2 (slow) in a triclinic medium. The isosurface show the wavefront of both P and S propagating away from the source. The traced rays are curved instead of straight in a homogeneous anisotropic medium. The polarization (red arrow) is different from the ray vector (blue arrow) due to the anisotropy.
The direct traveltime field of qP, qSV, qSH can be calculated by solving a Hamilton-Jacobi equation. With the traveltime field in 3D, the computation of rays and slowness vectors is straightforward. Note that the orthorhombic medium has a isotropic block at the center where the point source is located. The orthorhombic medium outside of the isotropic medium is obtained by perturbing an arbitrarily strong transversal isotropic medium. In other word, the orthorhombic is weak but the anisotropy can be arbitrarily strong. Here is the video: