File talk:Spherical digonal bipyramid.svg

This image of a "spherical digonal bipyramid" lacks a visible vertex at the midpoint of its upper edge

This image representing a "spherical digonal bipyramid" lacks a visible vertex at its top: at the midpoint of its upper edge

(& a hidden or "seen-through" vertex at its bottom: at the midpoint of its lower edge).

Indeed, any bipyramid has an upper apex (& a lower apex),

& the face configuration of the spherical digonal bipyramid is: V2.4.4;

so, each face must have 1 vertex connecting 2 edges (& 2 vertices each connecting 4 edges).

@Steelpillow: & @Redrobsche: & @Tomruen: do you agree on this point, please? :-) Bitte schön? ;-)

RavBol (留言) 01:52, 4 November 2020 (UTC)

That is true. However the graphic convention used for this family of drawings does not depict vertices as such, we have to infer them from where edges meet. It's just that in this case the edges meet at 180 deg so the vertex is invisible. To make it visible would be to change the graphic convention. I'd suggest leaving this image as it is and, on a page where the image is used, discussing whether a new set of images would be useful, such as on the English Wikipedia Bipyramid talk page. — Cheers, Steelpillow (Talk) 08:35, 4 November 2020 (UTC)

But nobody will ever bother creating a full new set of images, adding a round spot on every vertex of every spherical polyhedron...

As in e.g. Article: Spherical polyhedron, Section: Improper cases, Table: Family of regular hosohedra (spherical tilings), the most realistic solution is the following slightly adapted & clear graphic convention:

- the few invisible vertices are shown with a round spot;

- all visible vertices are just left as they are.

All the more so as with this slightly adapted graphic convention, an edge doubling an edge is still invisible... Readers must understand something!

@Steelpillow: & @Redrobsche: & @Tomruen: what do you think about this point, please? :-) Bitte schön? ;-)

RavBol (留言) 22:33, 6 November 2020 (UTC)