Hi,

first as basic info - technically it's only possible to draw flat elements/surfaces,

that means a cubical pano, which is build of flat surfaces, can be drawn directly as it is,

but a spherical pano on the other side has a curved surface, so it is necessary to split that curved surface into many small flat surfaces to draw it, so the curved surface can only be approximated,

the number of 'splits' is defined by the details parameter, the higher this value is, the more accurate is the approximation, but also the slower the rendering is,

you can play and test interactively different details settings with the options plugin,
there you can also enable the showing of the internal faces to see how the pano is internally organized,

best regards,
Klaus

Hi,

partially yes, the nadir and zenith areas are also better with cubes, because a sphere would need very much more triangles for good looking,

best regards,
Klaus