3D SBS or 3D Top-down ???

[Nestai]

Hello ... someone could explain, technically, that 3D is better, SBS or top-down??? Most jobs I see them in 3D SBS, but lately are many up-down too ... if there is already some similar thread sorry you pass me the link to see it.

Regards and sorry for the translation.

[Blue_MiSfit]

It's generally said that vertical resolution is more important than horizontal resolution. Therefore, side-by-side is theoretically better than top/bottom because it preserves full vertical resolution for both images.

[2Bdecided]

For interlaced content, side-by-side.

For progressive content, top-and-bottom is supposedly better because it maintains sharper vertical edges (= horizontal resolution) which are more important for 3D perception.

Not sure why Blue_MiSfit thinks the opposite because, apart from 3D, there's no visual reason to have unequal horizontal vs vertical resolution.

When viewed on passive displays which typically alternative each line between each eye (i.e. half vertical resolution per eye) top and bottom is far better since side-by-side effectively delivers 1/4 resolution to each eye (half vertical due to display, half horizontal due to side-by-side coding) on such a display.


The reason why horizontal sub-sampling is more common than vertical sub-sampling in normal 2D broadcasts is that, where people are trying to cram more TV channels in by squeezing bandwidth, H sub-sampling avoids worrying about the interlacing - and most broadcast channels aren't entirely sure whether what they're dealing with at a given moment is interlaced, progressive or telecined. Far better to squeeze horizontal resolution than worry about handling interlacing properly.

Cheers,
David.

[Nestai]

Thanks for the answers ... I do not understand is why the vast majority of rips are SBS instead of up / down "supposedly" gives more quality.

In passive 3D I can understand it better up / down, but not active 3D SBS 3D better not lose vertical resolution??? Like Blue_MiSfit, I also had understood that it is more important vertical resolution.

Thanks and regards.

Sorry for the translation.