I've not fully convinced myself of this sub file structure ...

hm, maybe more of the area around the hinge to the base and the chin area to the top (someone linked a helmet with a bottom area print)

Here's only one with a chin strap print I can find:
https://www.bricklink.com/v2/catalog/catalogitem.page?P=2446pb43

yes this one...
is the print on both sides?
https://www.bricklink.com/v2/catalog/catalogitem.page?P=2446pb02a#T=S&O={%22iconly%22:0}
goes quite low, nearly into the visor dent
(but there is a similar helmet with the same pattern smaller)

see Rene's comment here:
https://library.ldraw.org/tracker/25072

The helmet intersects with the body (973) in the standard setup
1 16 0 0 0 1 0 0 0 1 0 0 0 1 973.dat
1 16 0 -24 0 1 0 0 0 1 0 0 0 1 3626c.dat
1 47 0 -24 0 1 0 0 0 1 0 0 0 1 30124b.dat

It intersects at 0.266 LDU from the top edge of the torso
2 4 8.462096 .26662 -10 11.446698 .26656 -10

the plane of the Helmet bottom
0 // Current
4 13 -20 1.029 -16.21 -20 -2.732 14.424 20 -2.732 14.424 20 1.029 -16.21

should be moved by 0.3 LDU normal to the plane
0 // Move to (0.3 LDU normal to the plane)
4 10 -20 .7312 -16.2466 -20 -3.0298 14.3874 20 -3.0298 14.3874 20 .7312 -16.2466

the bottom of the helmet should be in this plane

What do you mean by "normal to the plane"?
I think it has to be moved 0.3 on the y-axis. The inside has to still fit around a head.

This collission is present in LDD, and I think it's the difference between a "perfect" CAD/Ldraw-world and the real world.
There is a radius on the torso. We dont have that in LDD/Ldraw.

the palne (i.e. the quad I inserted) is not parallel to the xz plane, so if this plane is moved by 0.3 LDU (like the second quad) it wound cause a collision.

Question is, shall it be fixed ot leave it as this happens with official data as well? Correction would be .12mm

Is studio complaining about such a collision?

IMO 1/10 of a mm isn't worth too much effort.

Release 2024-07