Visualisation of the orbital symmetry along the apsidal line (dash-dotted line) demonstrated a case of LC integration from a set of user-defined orbital positions (blue dots). Symmetrical orbital positions (grey dots) share binary models with symmetrical counterparts on the opposite ends of the grey dashed lines. Red dashed lines indicate positions of eclipse boundaries. The circled pair of orbital positions share the same surface geometry in the symmetrical counterparts approximation discussed in Sect. 7.2.2. The orbital positions are under-sampled for the sake of clarity.