Stellar orbit distribution in intrinsic radius r vs. circularity for mock spiral galaxies with inclination angles of 40°, 60° and 80° from top to bottom. Top panel: true stellar orbit distribution from the simulation. In the following three rows, the left panels are for models with incorrect mirroring, the right panels are for models with correct mirroring. The side panels compare the λ_z distribution for all the orbits at r <  15 kpc. The orbit distributions from the models with correct and incorrect mirroring are nearly identical, and they both present some difference with respect to the true distribution. The differences caused by the incorrect mirroring are negligible compared to the other systematic errors.