Why switching y-z in ShapeNetPart dataset preprocessing

[LiyaoTang]

Hi Hugues,

Since the publishment of your work KPConv, it has turned out to be a classic and popular backbone in 3D processing now.

While I'm currently trying to study KPConv in more detail, I find that the processing of ShapeNetPart is a bit hard to understand. Especially, is there any specific reason to switch the y-z axis in datasets/ShapeNetPart.py#L251C1-L252C1 ?

Besides, I find the normalization of the object point cloud uses the (min-max)/2 as the centroid position, instead of the normal use of the mean position of all points.

Best，
Liyao