Visualisation of merger orbits. Top: initial configuration of a direct-direct merger between two giant galaxies. In the retrograde-retrograde configuration, the orbital spin is flipped. The inclination i₂ is set to 0, 45, 75, or 90°. Galaxy 1 has a spin of coordinates (0, 0, 1), and galaxy 2, (0, sin i₂, cos i₂). Bottom: initial configuration of a direct-retrograde merger between a giant and a dwarf. In the retrograde-direct configuration, the orbital spin is flipped. The giant galaxy has an inclination i₁ = 33° and the dwarf galaxy, i₂ = 130°. Galaxy 1 has a spin of coordinates (0, sin i₁, cos i₁), and galaxy 2, (0, sin i₂, cos i₂). In both panels, dashed lines indicate that patterns are below the orbital plane or behind the discs.