[CTcard]

A very similar issue arose at the Olmpics in 2012 where it appeared that Phelps finished second in the 100 fly but ended up winning in a brobdingnagian surprise that many thought was bogus. Here is an article on how timing and photo finishes are used at the Olympics. 

http://olympics.time.com/2012/07/27/tech...-resolved/

Unfortunately, there are some ambiguities in the article (beyond the fact that it calls kg a unit of force).
We have both,

That’s how Phelps’ win in the 100 butterfly in Beijing was determined. The camera’s shutter clicks 100 images per second, and by comparing Phelps at the wall to Cavic, officials could see that Phelps finished first — by one image.

But also,

Fingers have to register at least 1.5 kg of force to be a legitimate touch;...
Which means that in the Aquatics Center in London, coming to the wall doesn’t just mean putting your hand on the touch pad first. It means pushing it — by 2 mm — as well

That seems to leave open whether the photo or the touch pad are the official determinant of the winner.

[I had always thought it was touch pad, but from that particular Phelps finish there was lots of talk about the photos being the ultimate arbiter. Somewhere I suppose the official rulebooks of FINA and the NCAA define this, but I don't have time to look just now.]


-------------------------
EDIT

So I looked up what is available on the web. FINA's rulebook is so short I cannot quite believe it is the actual rulebook, and doesn't really specify anything beyond automatic timing be used for official time and placements.
Here is the section on timing:
http://www.fina.org/content/sw-11-timing

USA Swimming has a more complete rulebook available.
https://www.usaswimming.org/docs/default...?sfvrsn=13
(see pages 39-40)
It is pretty clear that the primary system for determining times and placement is the touchpads (unless you don't have them - clearly not the case at an NCAA championships), and the overhead cameras are a secondary (backup) system. However, they maintain confusion by stating,

If  manually  operated  watches  are  not  the  primary  system,  a  secondary  system  of  precedence  equal  to  or  lower  than  the  primary  system  must  be  used.

I don't know how the secondary system can have equal precedence - if they disagree you have to use one or the other. Still, I am pretty sure that means you go by the touchpads are primary and the overhead camera is only if you have reason to believe the touchpads failed.


The NCAA itself has a rulebook that is ... pretty hard to read. As far as I can tell, all the words about video assume that it is only used as a backup to the automatic relay exchange judging system. The rules appear to make no mention of video for determining finishes or timing, and only notes touchpad systems as automatic devices for this purpose. Yet, they obviously had a video system in place, given the still frames above.
http://www.ncaapublications.com/productd...s/SW17.pdf

[CTcard]

A very similar issue arose at the Olmpics in 2012 where it appeared that Phelps finished second in the 100 fly but ended up winning in a brobdingnagian surprise that many thought was bogus. Here is an article on how timing and photo finishes are used at the Olympics. 

http://olympics.time.com/2012/07/27/tech...-resolved/

Unfortunately, there are some ambiguities in the article (beyond the fact that it calls kg a unit of force).
We have both,

That’s how Phelps’ win in the 100 butterfly in Beijing was determined. The camera’s shutter clicks 100 images per second, and by comparing Phelps at the wall to Cavic, officials could see that Phelps finished first — by one image.

But also,

Fingers have to register at least 1.5 kg of force to be a legitimate touch;...
Which means that in the Aquatics Center in London, coming to the wall doesn’t just mean putting your hand on the touch pad first. It means pushing it — by 2 mm — as well

That seems to leave open whether the photo or the touch pad are the official determinant of the winner.

[I had always thought it was touch pad, but from that particular Phelps finish there was lots of talk about the photos being the ultimate arbiter. Somewhere I suppose the official rulebooks of FINA and the NCAA define this, but I don't have time to look just now.]


-------------------------
EDIT

So I looked up what is available on the web. FINA's rulebook is so short I cannot quite believe it is the actual rulebook, and doesn't really specify anything beyond automatic timing be used for official time and placements.
Here is the section on timing:
http://www.fina.org/content/sw-11-timing

USA Swimming has a more complete rulebook available.
https://www.usaswimming.org/docs/default...?sfvrsn=13
(see pages 39-40)
It is pretty clear that the primary system for determining times and placement is the touchpads (unless you don't have them - clearly not the case at an NCAA championships), and the overhead cameras are a secondary (backup) system. However, they maintain confusion by stating,

If  manually  operated  watches  are  not  the  primary  system,  a  secondary  system  of  precedence  equal  to  or  lower  than  the  primary  system  must  be  used.

I don't know how the secondary system can have equal precedence - if they disagree you have to use one or the other. Still, I am pretty sure that means you go by the touchpads are primary and the overhead camera is only if you have reason to believe the touchpads failed.


The NCAA itself has a rulebook that is ... pretty hard to read. As far as I can tell, all the words about video assume that it is only used as a backup to the automatic relay exchange judging system. The rules appear to make no mention of video for determining finishes or timing, and only notes touchpad systems as automatic devices for this purpose. Yet, they obviously had a video system in place, given the still frames above.
http://www.ncaapublications.com/productd...s/SW17.pdf