[tjah1087]

This is a surprisingly easy mistake to make.

Background: I was one of the original engineers on the Goal Line Technology system now used by the vast majority of professional leagues.

Heads are surprisingly ball shaped from a a lot of camera angles, and the male balding pattern conspires to give a good impression of different football graphical designs.

When we were developing the system, we thought we had ball detection pretty nailed, and we never had false positives from any of the heads of engineers on the team. Then, our boss came to test the system ... As far as our algorithms were concerned, his head was exactly a football, just as in the article! Highly embarrassing, but everyone saw the funny side. It gave us better data and inspired a few more robustness checks that ended up being crucial later on! :)

[Luechkt]

Not sure how heads are "surprisingly ball shaped." What part of a round head surprises you exactly?

[evgen]

If you look at someone from eye level it is rather hard to mistake their head for a football. You need a certain amount of elevation before it actually starts to look like a sphere.

[tjah1087]

Yes, this.

Even looking like half a sphere is enough, as the system attempts to detect partially occluded balls too.

[szszrk]

To be fair, he did wrote "ball" not "sphere". I'm pretty sure my head and a ball share a lot of roundness but my head has way more parts that are sticking out. Also has way less of pentagon patches on it.

[Udik]

Seems pretty silly to try to classify a ball as a round object, period. A ball is a round object that doesn't sit on someone's shoulders.

[jon-wood]

Unless the camera is angled in such a way that a ball kicked up in the air obscures a player’s head.

[Udik]

This will happen, of course, but shouldn't last long. Also momentum of the tracked object should help.

Btw, funny that my comment above attracted so much hatred. Didn't want to sound like a know-it-all but yes, at least in the case of the referee I guess that checking for a body would have helped.

For example, in this stylised picture we can easily tell the player's head from the ball:

https://www.pngitem.com/pimgs/m/80-803112_italia-italia-90-l...