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Mapcode – A short address for any location on Earth

mapcode.com

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Re: Mapcode – A short address for any location on Earth

#101

Post by grey-area »

microcolonel wrote: post #86
lucb1e wrote: post #44

Honestly, I don't like it. At first I thought it was a short, sort of binary (at least machine-readable) representation of coordinates. A,A might be (0,0) in our coordinate system. Turns out it's not. It's not even global but country (or in the US, state) specific. This means that the locations are controlled by a single entity together with country codes. Sure, postal codes are controlled by a single entity too, but…

Mapcodes are coordinates within a rectangular region, you define the region, then the code(or if you're IN the region, you don't need to worry about defining it). One of the available regions is "Earth", which offers global coordinates(they're a bit longer, four or five characters on each side of the dot). The upside of this is that it is possible to implement it completely offline, you don't need to query the region…

One of the available regions is "Earth", which offers global coordinates(they're a bit longer, four or five characters on each side of the dot).

Why not just use lat, lon, which can be shorter too?

Central park, NY - 40.78 -73.97

Hyde Park, LON - 51.51, -0.17

Re: Mapcode – A short address for any location on Earth

#102

Post by frankus »

frankus wrote: post #99

I, for one, really like this. * It doesn't use postal codes, which aren't really intended for use for anything but mail delivery and occasionally make that painfully apparent (such as when the boundaries are changed) * It doesn't depend on street addresses, so it works in countries where the streets aren't reliably or intelligibly named/numbered. It also works in places where there are no streets. * It's smarter abou…

One more use case: When an address doesn't reliably geocode across mapping providers. I've run into this with things like campgrounds or tourist attractions in rural areas in the US and Canada, even with Google Maps but especially Apple Maps in the early days.

Re: Mapcode – A short address for any location on Earth

#103

Post by Alupis »

frankus wrote: post #94
Alupis wrote: post #74

Earlier quoted context omitted.

Hmm, I just took a look at their Java SDK... (clearly just sample code, but intended for embedding into your project to get going quickly) They make a lot of assumptions, and a lot of hard-coded values. For example, they seem to have lots of city names and country names hard-coded into a giant String array. ISO country codes are hard-coded (probably a safe assumption so-long as new countries are not added), many "mag…

81.JW4 is a lot easier to tell someone over the phone or transcribe from a business card or billboard, and it's pretty unlikely that the US-AK part would be ambiguous in those contexts. And if it is, a simple "which 81.JW4 did you mean?" would probably disambiguate pretty effectively.

Well, phonetically, pure numbers are better.

It's much harder to hear "eight" and mistake it for another number, but "P" and "T" are commonly confused (presumably people would read it as "Papa" and "Tango" to avoid confusion). What about "O" and "0", "I", "l", "1", etc. Now we have ambiguities that may not be interpreted correctly, even with phonetics.

Re: Mapcode – A short address for any location on Earth

#105

Post by javadocmd »

jisaacso wrote: post #29
grey-area wrote: post #14

Objections: 1. This mapcode is country specific (!) 2. Many locations need altitude or fine lat,lon differences to differentiate them (e.g. blocks of flats, offices). 3. What's wrong with altitude, lat and lon on a given projection which can be as precise/imprecise as you want? IMO it'd be better to have a hash of lat,lon,altitude which was globally unique for each level of precision. A system like this needs to be g…

There exists a hash of lat, long globally unique for each level of precision, a geohash [1]. One common application utilizes a space filling Hilbert curve to define an arbitrary precision bounding box around a set of coordinates. You can see an example hash [2]. [1] http://en.wikipedia.org/wiki/Geohash [2] http://geohash.org/9q8yyvfekk8h

If you'll pardon the reckless self-promotion, there's a few Java implementations to do Geohash calculations: https://code.google.com/p/simplelatlng/

Re: Mapcode – A short address for any location on Earth

#106

Post by frankus »

Alupis wrote: post #103
frankus wrote: post #94

Earlier quoted context omitted.

81.JW4 is a lot easier to tell someone over the phone or transcribe from a business card or billboard, and it's pretty unlikely that the US-AK part would be ambiguous in those contexts. And if it is, a simple "which 81.JW4 did you mean?" would probably disambiguate pretty effectively.

Well, phonetically, pure numbers are better. It's much harder to hear "eight" and mistake it for another number, but "P" and "T" are commonly confused (presumably people would read it as "Papa" and "Tango" to avoid confusion). What about "O" and "0", "I", "l", "1", etc. Now we have ambiguities that may not be interpreted correctly, even with phonetics.

FWIW they left O and I out of the list of possible letters for just that reason.

One could argue either way about fully-numeric versus alphanumeric codes. They're a bit harder to communicate but more than three times shorter, on average.

Edit: math is hard. One and a half times shorter, on average.

Re: Mapcode – A short address for any location on Earth

#107

Post by richardw »

cabalamat wrote: post #82
lstamour wrote: post #56

Earlier quoted context omitted.

Actually it's that those MapCodes are incomplete. They're missing the country/state designation. If you look up "Ireland 0C.T4" or "US-AK 0C.T4" you should get the correct results. I'll cite a .doc file here, it's also available on the Developers page: > 1. Codes only need to be accurate enough for public, every-day use. At the human scale, when you are within a few meters of a destination, you are “there”. > 4. Peop…

> Actually it's that those MapCodes are incomplete. They're missing the country/state designation. If you look up "Ireland 0C.T4" or "US-AK 0C.T4" you should get the correct results. Imagine if a URL resolved to different addresses in each country you were in. Would that be a better system than what we have now, or a worse one? I think it would self-evidently be worse. I'm surprised they didn't make mapcodes a global…

Phone numbers are very similar. They have a short and long representation and the short is often duplicated in different countries. Imperfect but a very human solution: works because it's easy and 99% of the time we call the right number.

Re: Mapcode – A short address for any location on Earth

#108

Post by dang »

beseku wrote: post #2

Subtitle taken from http://www.telegraph.co.uk/technology/news/10975625/Did-TomT...

It's against the HN guidelines to editorialize in titles, even when the editorialization was done by somebody else.

This one was particularly bad because the submitted title ("Did TomTom founders just kill the postcode?") caused the post to receive a barrage of user flags.

Re: Mapcode – A short address for any location on Earth

#109

Post by jofer »

jxf wrote: post #22

I'm a little confused about what this replaces, but it's definitely not postcodes. * Postcodes have a specific meaning: they're both a geographical area and a mail delivery zone (at least in the US). Replacing one short code with another, which requires a different and less reliable third-party service to correctly decode, doesn't seem like a good idea. * Latitudes and longitudes are unambiguous, well-understood, and…

> "Latitudes and longitudes are unambiguous..."

This is a tangent, but actually, they're not.

There have been (oil) wells fail because someone gave a lat/long without specifying the datum, and someone else assumed it was in a different datum.

Without a datum defined, latitude/longitude (no matter how precise) only gets you to within ~1km of an actual location.

The Earth is not a sphere (or even an ellipsoid). Therefore, we need models of the the absolute shape of "sea level" (i.e. an equipotential surface - varies due to density variations in the Earth) to go from a spherical coordinate system to an actual point on the Earth's surface. These are referred to as a datum.

Because our knowledge of the absolute shape of the Earth has changed over time, there are many different datums (ranging from spheres to ellipsoids to detailed gridded surfaces).

There are a large number of datums that are still in common use. WGS84 is the most common (and very accurate), but NAD83 and NAD27 are also very, very common, as well as many others. If someone gives you a lat/long in NAD27 (e.g. read off of a printed map) and you assume it's WGS84, you can wind up over a kilometer away from the original location. (NAD27 is reasonably accurate for the US, but is very inaccurate elsewhere on the planet. I regularly see it used for data everywhere, though.)

Re: Mapcode – A short address for any location on Earth

#110

Post by kghose »

jofer wrote: post #109
jxf wrote: post #22

I'm a little confused about what this replaces, but it's definitely not postcodes. * Postcodes have a specific meaning: they're both a geographical area and a mail delivery zone (at least in the US). Replacing one short code with another, which requires a different and less reliable third-party service to correctly decode, doesn't seem like a good idea. * Latitudes and longitudes are unambiguous, well-understood, and…

> "Latitudes and longitudes are unambiguous..." This is a tangent, but actually, they're not. There have been (oil) wells fail because someone gave a lat/long without specifying the datum, and someone else assumed it was in a different datum. Without a datum defined, latitude/longitude (no matter how precise) only gets you to within ~1km of an actual location. The Earth is not a sphere (or even an ellipsoid). Therefo…

Thanks for teaching me about datums: http://en.wikipedia.org/wiki/Datum_(geodesy)
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