Interesting Items...

[Black Hole]

According to Wikipedia, at latitude ±85° the scale factor of the Mercator projection is 11.5. This means an area on the map which corresponds to a 3m square at the equator, at ±85° latitude corresponds to a square* less than 30cm (although there might be a scale factor which makes the W3W squares larger than 3m at the equator and correspondingly larger everywhere else, to even things out)! And I still don't know how W3W caters for the polar regions.

Reminder: if W3W were not allocating locations on a Mercator projection basis, the grid of squares on their website (overlaid on Google Maps) would not be squares!

* The Mercator projection is mathematically designed to preserve azimuths locally – as an aid to navigation by compass bearing. This means it is not a geometric projection (eg cylindrical projection). It also means small areas on the map are the same shape as heir corresponding areas on the ground, but not necessarily the same scale (and this breaks down at the poles because the map would have to extend to infinity to include the poles).

 

[MikeSh]

How many could before?

Exactly. Emergency use is only one application for W3W. It's intended for any location coordination like meeting a friend somewhere.

 

[Black Hole]

It's intended for any location coordination like meeting a friend somewhere.

I'm not arguing with that. My complaint is that it doesn't do what it says on the tin, and it is not sufficiently reliable for critical applications. Neither does "meeting a friend somewhere" feed their business model.

 

[MikeSh]

Reminder: if W3W were not allocating locations on a Mercator projection basis, the grid of squares on their website (overlaid on Google Maps) would not be squares!

You are banking everything on it all being Mercator based, but that's only the visualisation.
I suspect they have done something more akin to dividing the globe into points 3m apart with the reference coordinate at that point. On the display they show the points locally as 3m squares. (As you zoom out the squares disappear before the triangle effect becomes visible.)
That will obviously lead to some misalignments on the latitude rows as you move away from the equator, so there is likely some jiggery-pokery going on - perhaps with the 3m spacing changing a bit and points out at sea getting closer together and eventually merging/disappearing.

 

[MikeSh]

not sufficiently reliable for critical applications.

Do you think ambulances are?
Or helicopters?

What reliability is good enough?

I'm not saying W3W is perfect but it's a useful tool and one I have on my phone and have used. I'm sure the reported problem words can be fixed without too much bother.

 

[gomezz]

Eh? How?

You tell the rescue service you are on the side of a mountain. You tell them a grid reference which actually puts you many miles away but by inspection it can be seen that if you transpose two of the digits that gives a grid reference on the side of the mountain. Try doing that with W3W were any slightly mistake in the spelling (were instead of where for example) puts you even further away without a clue as to what change to the spelling gets you back on the side of the mountain.

 

[Black Hole]

You are banking everything on it all being Mercator based, but that's only the visualisation. I suspect they have done something more akin to dividing the globe into points 3m apart...

Demonstrate your case – I think you are just guessing. I've been looking at this for some hours, and I have found nothing to refute my assertions. If the locations specified by a W3W coordinate were truly spaced 3m apart, at 85° latitude 100 squares on the map would have the same W3W coordinate. Click in each box and you get a different W3W. To me, that says there is a 1:1 correspondence between the W3W grid and the Google Maps projection, which is Mercator.

I accept it might work well enough in the major populated areas, but W3W claim to cover the poles and I have seen no evidence of that, and the blurb W3W has put out is inaccurate at best.

I'm sure the reported problem words can be fixed without too much bother.

From the W3W FAQ:

The words are distributed by a mathematical algorithm; they are fixed and will never change.

what3words addresses are fixed and will never change. That’s how what3words is able to work offline and needs no updates or database. We know a lot of people would like to personalise the words in their addresses, but this can’t be done.

...so "fixing" them is not an option, unless they are lying.

The reason there are "problem" words in the first place is because there are too few words in the vocabulary of the "man on the Clapham omnibus". The problem of single-letter differences cannot be solved without introducing a raft of obscure words, and that's just for English (possibly the richest language in the world). Their "mathematical algorithm" has allocated where these words get used, so neither can they fix that the similar words turn up not far enough apart. My solution: make it W4W.

W3W's business model is to sell look-ups to major users (small users get it for free, up to 1,000 look-ups per month). In order to attract major users, I believe they are overplaying their hand by making unsubstantiated claims. It's not the general principle I am criticising, it's the unsubstantiated claims.

In short, I conclude that W3W has been set up by some clever IT people with an idea, and not anybody who knows anything about cartography. Hell, they might not even realise Google Maps tops out at 85°05113!

 

[Black Hole]

You tell the rescue service you are on the side of a mountain.

So you haven't only specified the GR then. Extra information.

You tell them a grid reference which actually puts you many miles away but by inspection it can be seen that if you transpose two of the digits that gives a grid reference on the side of the mountain.

That's guesswork. Transposing a different couple of digits could well produce a different "side of a mountain". No, sorry, you might get lucky but you couldn't rely on it.

 

[MikeSh]

If the locations specified by a W3W coordinate were truly spaced 3m apart, at 85° latitude 100 squares on the map would have the same W3W coordinate.

I can see in my mind how it might work but beyond my earlier suggestion I can't currently think of a way to explain it clearly.
I'll post it and maybe have a look in W3W to see if my idea fits.

From the W3W FAQ:
...so "fixing" them is not an option, unless they are lying.

OK. They do seem to have dug themselves a hole there.

it's the unsubstantiated claims.

Well, it's a business.
Not that making such claims is limited to them these days . Trump has legitimised that.

 

[gomezz]

So you haven't only specified the GR then. Extra information.


That's guesswork. Transposing a different couple of digits could well produce a different "side of a mountain". No, sorry, you might get lucky but you couldn't rely on it.

Thus speaks an inexperienced map reader.

 

[Black Hole]

Thus speaks an inexperienced map reader.

On the contrary sir!

To change the subject: I realise it is a fools errand to try extracting logical consistency out of sci-fi, by Voyager is supposedly heading home from the Delta Quadrant at what I calculate is 1000c. Yet somehow other species are able to catch up with them or hear rumours of their presence. Hmm.

 

[Black Hole]

Thus speaks an inexperienced map reader.

OK: Help, I'm trapped in a gully on the Black Mountains at GR SN746196. My phone is now out of battery.

There's nowhere for a chopper to land in that area, so they send out mountain rescue who proceed to the stated coordinates but find no casualty. What next?

 

[MikeSh]

What next?

They use their Mk1 eyeballs for a while and maybe they/you get lucky.

 

[EEPhil]

Yet somehow other species are able to catch up with them or hear rumours of their presence. Hmm.

Doesn’t make a lot of sense. But with radio signals also travelling at several times c as well anything is possible - even a ship that rearranged itself.

 

[EEPhil]

What next?

Send for a proper rescue chopper with a winch. Now you’ve gone missing make sure it has a thermal imaging camera as well.

 

[Black Hole]

They use their Mk1 eyeballs for a while and maybe they/you get lucky.

But they're off by several km. Gomezz seems to think they/he could resolve the grid ref error using map reading, so I would expect he can come up with the actual grid square. And that's the point of What3Words (if only it didn't have ambiguous words in the set).

 

[MikeSh]

But they're off by several km.

If there aren't too many gullies (assuming you told them you were in one when giving the reference) they might realise the ref is wrong and start trying permutations.

TBH all important info like this should be backed with a sanity check, like "I'm a few miles SW of Keswick". (Yes, there are people who get in trouble and have no clue where they are - a county if you're lucky. But the Darwin Award has to have some competition. )

 

[Black Hole]

If there aren't too many gullies (assuming you told them you were in one when giving the reference) they might realise the ref is wrong and start trying permutations.

That's Gomezz's argument, but I say it is impractical. Just take a look at the map. And do you really think anyone's going to test all plausible errors and permutations?

 

[MikeSh]

And do you really think anyone's going to test all plausible errors and permutations?

I really don't know. If they are looking at a long search pattern with multiple SAR resources being allocated I'd hope they analyse everything they've got, including the possibility of a hoax. I expect phone masts would be thin on the ground, but at least they can find out which one you connected to which would narrow the possibilities to a few miles radius (probably much less if you are in a gully.

Which raises the other elephant in the room - If you are in a remote spot you'll be lucky to get a signal anyway.
A few weeks ago I was out in the New Forest at a lower altitude (near a river) when I saw something a bit odd and decided to report it. Given the NF is so renowned for it's mighty hills and mountains I pulled out my phone to find ... no service. Had to continue about a mile to higher ground before I was able to make the call.

 

[gomezz]

OK: Help, I'm trapped in a gully on the Black Mountains at GR SN746196. My phone is now out of battery.

There's nowhere for a chopper to land in that area, so they send out mountain rescue who proceed to the stated coordinates but find no casualty. What next?

Is there any relationship between the correct reference and the reference you gave?