Talk:Main Page

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• Use Template:Graticule to generate a map of the graticule for graticule pages.
• Use Template:Meetup graticule to generate a map of a day's location for meetup/expedition pages.

Problems with original implementation east of 30W

I don't suppose its possible for me to get the map tag on 2008-05-21_54_-2 to show the coordinates as they were when the trip was made, ie, under the original rules? Nicktaylor 18:14, 24 May 2008 (UTC)

Not presently. I'm surprised Randall didn't write a split-date into his implementation. --Tim P 20:09, 24 May 2008 (UTC)

Update: I've updated Template:30w compliant to allow for implementations to be flagged as partially compliant. I've also updated the Implementations page accordingly to show that the official interactive calculator (which is used by Template:meetup graticule) falls into this category. Hopefully all will be resolved soon. --Tim P 20:25, 24 May 2008 (UTC)

Someone has pointed out that you can subtract 360 from the longitude to get it to show properly. This is fine as a temporary solution, but backwards compatibility, I think a full implementation should either automatically use the old algorithm before 27-05-08, since that's when this site claims the new rules come into effect, or at least offer a parameter to choose the old algorithm. Nicktaylor 23:33, 24 May 2008 (UTC)

Agreed. --Tim P 02:09, 25 May 2008 (UTC)

I might be wrong, but it seems that there either are, or were, problems with the implementation on http://irc.peeron.com/xkcd/map/ . It seems to me that if I enter a day, for example 22 May, I should get the same result as I used to get on 23 May in the original pre-30W-rule implemntation. However, this is not the case. 145.97.227.131 01:31, 25 May 2008 (UTC)

Firstly, the reference implementation is not backwards-compatible with 30W. That is, it applies the 30W Rule retroactively to all dates, even those before its intended effect on Tuesday, May 27. I've addressed this issue on the Implementations page. Secondly, the 30W Rule does NOT say to use the previous day's coordinates altogether; rather, it says to use the previous day's Dow opening with the current date when hashing the algorithm. As such, locations east of 30W should get a completely different set of coordinates than locations west of 30W for any given day. This isn't viewed as a problem because, with the exception of northeastern Greenland and perhaps some small islands, 30W does not cross anywhere inhabited. --Tim P 01:57, 25 May 2008 (UTC)

Thank you, you are right, I overlooked your second point. 145.97.227.131 02:45, 25 May 2008 (UTC)

Conventions

You might want to come up with some basic conventions and outline them very clearly, very quickly. This site is going to explode pretty quick, and without any, it will become a mess.

EG:

- Region/Graticule pages named "City Name, Country" where "City Name" 
    is the most major (by population) urban center contained within it.
- Activity pages named "YYYY-MM-DD GRATICULE"
- Graticules referred to by top-left coordinate.
- Hell, create a template for region/graticule pages so they have some semblance 
    of consistency. And some sort of outline on what it should contain
- (Descr of region, image of graticule, Activities Section, Notable Events Section).

Should states be abbreviated or spelled out in the list of graticules on the Region/Graticule pages? Currently is a hodgepodge and the OCD in me is cringing. --KDinCT 20:14, 21 May 2008 (UTC)

Just my $0.02. NuclearDog 10:20, 21 May 2008 (UTC)

I think I like the first options best, makes searching (through Special:Allpages, especially) considerably easier. Working on Eindhoven, Netherlands right now. Also it might not be a bad idea to keep discussions on upcoming meetings to the talk pages. Nazgjunk 14:23, 21 May 2008 (UTC)

I personally just wanted to add that we need to set a convention on how the locations are listed. I personally liked them ordered by latitude and longitude (east to west and north to south) but they appear to be recently edited into alphabetical order. Which I do not think is as 'smart' because they are listed by only one city in the area and someone might accidentally add the area again using a different city. Once the list is long duplicates will be hard to spot.--h[User:KDinCT|KDinCT]] 15:19, 21 May 2008 (UTC)

The list of graticules on the Main Page gets this right, doesn't it? That is, the instructions are there. Execution of those is PEBKAC, of course. Nazgjunk 15:22, 21 May 2008 (UTC)

This has since been fixed back into locational order. --KDinCT 15:32, 21 May 2008 (UTC)

In most cases, though, these are sorted NtoS and then WtoE. In many cases, it would make much more sense to sort WtoE first because we already do that mentally with time zone divisions. --Tim P 22:58, 23 May 2008 (UTC)

Graticules should be named by their lower right corner since the algorithm adds to the graticule's integer, right? Actually... it would be: (Lower right in NW Hemi, Lower left in NE Hemi, Upper right in SW Hemi, Upper left in SE Hemi.) That seems a lot for a convention, but all you have to say is "graticules are areas with the same integer coordinates." --TLP 15:30, 21 May 2008 (UTC)

I noticed that this convention causes the name of the graticule to not match the link. Is that an issue? --Scooter 18:32, 21 May 2008 (UTC)

Yeah I just saw that too, but only in some places. Dublin is linked from the bottom left, Bremen is linked from the bottom right. 9i would think it would be reversed, but it's not...) --TLP 21:38, 21 May 2008 (UTC)

What should the convention be when a main city is split (ex. 61, -149(or -150) (Anchorage, Alaska) and 41, -96 West of 56th St; 41, -95 East of 56th St. (Omaha, NE))? My view is that these areas should be seperated and one will get visited sometimes and the other will get visited other times.--KDinCT 15:32, 21 May 2008 (UTC)

What if in a case like that, you have a city page that links to the individual graticule pages in the area? For now, you'd still leave the graticule pages on the main page. I'm thinking over this problem too for Philadelphia -- the city is basically on top of (40, -75) so there's 4 graticules in the area, only one of which I've named Philadelphia. --TLP 15:52, 21 May 2008 (UTC)

I'd say in your case, for example, the same Philadelphia link should be listed four times (once per graticule) on the Main Page. The target page will explain the multigraticule situation, and maybe any locality-specific ways you handle individuals perhaps using more than one. —Christian Campbell 18:58, 21 May 2008 (UTC)

Yeah that could work maybe. It definitely would for just two graticules, but I wouldn't want to put four of them on one page, especially since the NE one in this case includes Staten Island and lower Manhattan. --TLP 21:40, 21 May 2008 (UTC)

In graticule pages, I suggest using the following template: {{graticule |map=<map lat="37" lon="-122"/> |e=East Bay, California |ne=Sacramento, California }} Zigdon 02:08, 22 May 2008 (UTC)

Automatic land-water filter / other filters

geosplashing
Pyron Beta 12:42, 21 May 2008 (UTC)

Does anyone know of open-source data for determining whether a coordinate lies on land or water? This would be an interesting feature in a calculator which tries to automate this a bit so one does not have to manually check against a geohash calculator every day.

E.g:

• every morning, calculate the days geohash
• apply filters:
  • is coordinate on land?
  • is coordinate not in known list of bad regions (area 51, etc.)
  • other personal filters, e.g. is coordinate < n miles from home
• if pass all filters, notify of coordinate, provide image of (or link to) map

--Recursive 11:15, 21 May 2008 (UTC)

Hmm. Seems like http://www.openstreetmap.org/ found this data somewhere, so presumably it's only a matter of digging up that separate dataset and parsing it. Here's another mess of links: http://opensourcegis.org/

OSM has some form of land detection, but it's a little crude. The readme in [1] should provide the details required. -- Edgemaster

(of course, this isnt the exact data in the OSM database, but a highly simplified version) If you want to go to the trouble of parsing all of the coastline shapefiles, they're here: [2]

And a third edit to say that we use this datasource.

Of course, having the data is not necessary, merely being able to query a web service for whether a coordinate is land is sufficient. The crudest approach would be to graphically scrape google maps, but, that's kind of lame. --Recursive 11:24, 21 May 2008 (UTC)

So i'll assume by kinda lame you meant awesome and i went ahead and implemented that, here it is: Enjoy

Wouldn't it be simpler just to have a standardized method of determining where to go if the geohash is over water? Say, "Follow shortest straight north, east, south, or west line to land and meet at the coast" or something along those lines. -- Curtmack (67.141.84.48 01:44, 22 May 2008 (UTC))

But whats the point of simple when it ruins my fun. Also i think it'd be better to try to keep everyone meeting at the geohashes or as close to as possible. Then we'll get custers of people. More people means more fun :). check out the implementation of this here: [Finding Alternative Geohashes]

Hence the point of a standardized method. Although I agree, it is more fun to try and go over water, but it could be horrendously difficult and downright impossible in some cases (i.e. your geohash is several miles out on water and all you can conceivably rent is a rowboat). Just a thought anyway. Curtmack 00:26, 23 May 2008 (UTC)

Active Graticules

Can it be done to automatically sort the active graticule list? --Psud 11:49, 21 May 2008 (UTC)

be useful if people started catergorizing their pages too --Ryan the leach 12:34, 21 May 2008 (UTC)

What if we redo the active graticules entirely? Better soon than later. Create a "Active Graticules" page with lists of all graticules, and then only list the most active graticules on the main page? --Tsen 13:53, 21 May 2008 (UTC)

Agreed. There should be a page of ALL graticules and then once it has had more than 5 visits (or some other arbitrary number) it can be moved to the 'active graticules' list on the main page. --KDinCT 14:10, 21 May 2008 (UTC)

How can we add new Graticules? I live in South Africa and Geocaching itself is a becoming a big deal. Can we add an African region? More specifically a South Africa; and then Johannesburg?

Just edit the main page, copy/paste an existing entry, alter it to match your location and save. It should create a link to your page, which should still be blank. Then edit that, (perhaps copy/pasting another graticule's page to keep a semblance of order) and add all you want.

On another note, I'd be willing to reorder the pages for Active Graticules and cut down the bulk, but what criteria should we use for "More" active graticules? Since this has only really hit the interwebs in the last day, there hasn't been time to see which areas are really going to be busiest. Do we create an active graticule page now, removing them all from the front page and then adding more active/interesting ones to the main page as they come up? --Tsen 03:25, 22 May 2008 (UTC)

What about just having categories for "at least 10 users", "at least 50 users", "at least 100 users", "at least 500 users", "at least 1000 users" etc. There seems to be a convention developing of listing user names in each graticule for those who are interested in participating (though this probably doesn't scale well... perhaps an average count of recent Saturday participants instead?). Then as time goes by and they grow, we can just start linking to bigger and bigger category pages to see the most active groups. --Cahlroisse 05:44, 22 May 2008 (UTC)

I would suggest that, after this weekend, a graticule is only listed as active if a meeting has taken place. That is, it has been proven that at least two strangers have actually met on a weekend by geohashing in the graticule.--121.73.94.250 05:55, 24 May 2008 (UTC)

But what if it was inaccessible? --Tim P 20:55, 24 May 2008 (UTC)

Small Islands / Countries

One problem with this are small countries such as Malta ([3]). It's split into two reagions and both are very small relative to the degree grid box. It would make more sense two have the entire country as part of a single region (i.e. shift by half a degree). This of course would not occur to you, big country - americanites ;)

I don't see why this would be a problem since if it is a point on the western part of the grid then you go to the east side of the island (and it's associated degree grid box) and if it is a point on the eastern part of the grid then you go to the west side of the island (and it's associated degree grid box). But then again I am just a big country Americanite.

We could, for such case, agree to add .5 degrees to the coordinates as needed to have the meeting point on land, or you could just all agree to swim or row to the meeting point instead. - Sparky

Yeah, in Halifax NS (where I live), most of the square is in the sea. In Victoria BC, (when I happen to be right now), a good chunk of the square is in the sea, and a good chunk is in another country. In Wellington NZ (where I'm from), most of the square is either in the sea or an expensive 3-hour ferry ride away on another island. I suggest that you should be able to set the centre of the square with a higher granularity - say 1/10 of the square size. Then it's still not too hard to make sure everybody is using the same square, and it allows you to position the square such that it's mostly overland, and mostly in your country. 24.68.238.83 14:06, 21 May 2008 (UTC)

I've said this before, and I'll say it again: the boundaries of the cells are completely irrelevant, because the meeting point is in the same place in every single cell. The meeting points are exactly 111km apart in both directions, and there will be a meeting point within ~78km of every single point on the surface of this planet. If that point happens to be 30km out to sea, there will be another one 111 - 30 = 81km inland. If you live on an island which is significantly smaller than 111 * 111 km, well, you're just not destined to meet people, I guess ;-)

Okay. Don't get me wrong. I agree with the system, but what you're saying isn't entirely correct. It is possible to have meetup points further apart than that. Like, for example, what if you lived in Haywards Heath, UK. It's close to the Prime Meridian. Because of the algorithm, it's possible for the geohash to give something like .99999 west or east. Like for example May 11. It's just a hair over that, but it's possible to get further. (Greenwich may 18th...). McKay 15:21, 21 May 2008 (UTC)

Yes, you are entirely correct. I didn't realise that the algorithm mirrors the coordinates around the 0 medians (on the north-south and east-west boundaries). This artifact of the algorithm can be removed by inverting the fractions in, for example, the east and south hemispheres. - Sparky

Zero degrees longitude

Note that there is a negative zero, for those of us near the Prime Meridian (e.g.: London). The algorithm will then lead to longitudinal coordinates such as -0.1234 instead of 0.1234.

Correct - this is by design. Zigdon 14:55, 21 May 2008 (UTC)

Heh, indeed - To clarify, I added this info because London West was originally listed as longitude -1 (as opposed to -0). I didn't intend to imply it was a problem to have negative zero, I just wanted to flag the issue. Sorry for any confusion. 194.74.151.201 16:19, 21 May 2008 (UTC)

Actually, it appears zones are numbered with the WESTMOST longitude coordinate. In the west, it doesn't make much intuitive sense, because, for example, all locations in a zone labeled with -80 longitude begin with W 79°. As such, London West actually is -1. Tjtrumpet2323 22:21, 21 May 2008 (UTC)

A heads-up to the person who created the rss feed: the script doesn't recognise the existence of -0, but if you pass it -1, you get (as you shoulld) a longitudinal co-ordinate -2 < x < -1. There's no way to get any of the graticules where -1 < x < 0.

If this was by design, then can the design please be reconsidered? For everyone else, the maximum distance to a meetup is the diagonal length of a graticule, but for people on zero degrees longitude / latitude, it's further than that. For instance, the nearest two meeting points to me (in Cambridge UK, at 52, 0) are at 52.179467°, 0.861536° and 52.179467°, -0.861537°, both of which are too far for me to visit. Can we change the algorithm to round down, rather than truncate, the starting location? -- lilac

The map tag for the graticule template also doesn't recognise -0 - for example, it is impossible to add a map to Northampton, United_Kingdom, the map just keeps centring on Cambridge. Nicktaylor 14:12, 23 May 2008 (UTC)

This will be fixed shortly - you will able to specify the 'abs=1' tag, which would mean that entering "-1" would be the grat between -1 and 0 (instead of -1 and -2). Zigdon 17:43, 23 May 2008 (UTC)

Am I to understand that with the new parameter, one will be able to directly specify the integral portions of their home coords? That would be ideal. In any case, please make sure that the reflections around 0 (both E/W and N/S) end up being very well documented when you make this change. At times, the Active Graticules page has been a mish-mash of many systems. --Tim P 22:16, 23 May 2008 (UTC)

I created the -0 Issue to summup this problem (and to bring a solution).

Negative coordinates and adding versus appending

There's possibility for confusion with regard to graticule coordinates. For example, the larger NYC graticule's longitude ranges from -73 to -74. If, like it seems in the comic, you're supposed to append the random <1 number to the coordinate, then NYC's graticule should be listed as 40, -73 (since every point within the graticule has longitude -73.xxxxx). If, however, you're supposed to add the random <1 number to the graticule, then NYC's graticule should be listed as 40, -74 (since the random number is always positive, this will always lead to a -73.xxxxxx number unless the random number is zero). I therefore recommend changing the algorithm to specify adding the random number, not appending it.

As a side note, the implementation of the algorithm linked to from the comic reflects this confusion. If the link includes the 'abs' parameter, it gives the coordinates of the NYC graticule as 40, -74: http://irc.peeron.com/xkcd/map/map.html?lat=40&long=-74&abs=1 However, if the link does not include 'abs' parameter, the longitude has to be changed to -73 to give the same graticule: http://irc.peeron.com/xkcd/map/map.html?lat=40&long=-73

The map always marks the northwestern edge of the graticule - otherwise, it'd have to add a parameter for N/S and E/W. So when given the 'abs' argument, it takes your coordinates as the northwestern corner, and without it they're parsed as what the comic presents them as. Perhaps this should be made more explicit though. Zigdon 18:22, 21 May 2008 (UTC)

This absolutely needs to be made more explicit. --Tim P 23:44, 24 May 2008 (UTC)

Larger Events

If this turns out to be successful, I think it would be nice to group sets of graticules together and have state- or even national-based events (although this may be tricky in nations that cross timezones... maybe we could just have time-zone based events) for special occasions. StJimmy

How are you going to do that when you have no idea where you'll be going or even if it's public property? Gormster 15:38, 23 May 2008 (UTC)

Who owns the land?

One of the things that early geocachers quickly learned is that even public land that they thought would be safe to hide a geocache on ("...it's not harming anyone...") was "owned" or cared for by someone. I think geohashing is going to quickly run into a similar problem. You will get your coordinates, everyone will rush out there and maybe you'll even find a public right of way that leads you close. But the times someone ends up on private property chasing their GPS signal or people go off-trail in a public park against posted policies or whatever slight someone takes like if they land in a graveyard and some participants still want to play "games" upon arrival, well, those are the ones that geohashing will be remembered for and the people who follow out there that day are not going to have any idea what kind of hurt feelings or possible repercussions they're about to run into when they arrive.

Just a caveat from a learned geocacher for geohashers to keep in consideration. No means no and even the times when you think you're in the right, you might be doing more harm than good by forcing the issue. Be smart from the time you leave the house to the time you determine you have no right to go any further. 24.218.222.86 01:59, 22 May 2008 (UTC)

I agree with this, to some extent. The point of this idea is adventure, so we sort of want to have weird places to try to get to. But sadly we can't just walk anywhere we want, so some filtering of the locations might be in order. "bad" locations that end up on private land or non-walkable locations might get moved to the nearest accessible point or recalculated with some predictable randomness added to the hash until an acceptable solution is found. This would probably be hard to implement correctly though, and it could be that a super simple solution is best. - forest

You're not thinking globally. No one can pick a proper new location every day for every place in the world. Yes, some days the locations in your area might not work out, that's too bad. Try again tomorrow! Zigdon 06:43, 22 May 2008 (UTC)

Think more pragmatically: How early in the process can you determine that the day's location will "work out"? Is there a way to learn from others' experiences for the day that the site didn't "work out"? What is the impact on the person who owns the land where the hash isn't "working out" when people will just continue to show up unannounced? How can the geohashing/xkcd community avoid a bad rap for following a "wierd internet trend" that leads people to just showing up en masse on a stranger's front yard/street corner/field? Those are a lot of the same questions that geocaching (particularly non-Geocaching(tm) geocaching) has had to deal with. Geocaching(tm) avoids some of this by requiring approval for locations and methods of hiding before being listed for the world to see. Here, the hash is determinable without any central authority or QA. This means there's little control over the actions of the community members...which could mean problems for the community and the activity as a whole that should be given some consideration.

My answer would begin with laying out some guidelines in a high profile place, like this wiki's Main Page, to help shape how new community members may be influenced. Some things may be obvious to certain people who come here to "just have fun" or "go back another day" but you'll find someone who will want to do something like a "10 days in a row Achievement". There will be community members with less self-control who will want to run through someone's property just to "catch'em all" or keep up their streak or whatever have you. Again, these are just some of the issues I have seen in geocaching which may even be more exacerbated by the fact that you don't even need to search or leave something behind to geohash, therefore you're more likely to see less harm from trying to reach your coordinates when they're not legally accessible. I haven't even gotten to the warped problems, like having a group of 4-5 people meeting up in the bushes at a public park, just to get reported because they're less than 30 feet from a group of children playing in a sandbox. Then there's the xkcd twist in that situation...half of the hashers are wearing raptor masks and the other half have swords. 24.218.222.86 18:00, 22 May 2008 (UTC)

I got distracted from your point by your awesome idea at the end... =-)

Um, back to your point. You're right, geohashing has nothing to protect. Geocaching wants to preserve the ability to place things and the expectation of finding them again. Geohashing wants to preserve people showing up randomly. The only way to screw that up is to overregulate it. Not to say we won't individually want to minimise hassles with less lateral thinkers, but don't we deal with that daily?

I think the allure is doing something orthogonal to "normal," and "approved" is a directly conflicting goal.

Now, we like figuring out systems, so you could probably with some success cast a best practices guidelines section as a parameterisation of what property owners/police want to perceive. Taking that idea too far, we could have a cover story where we're all in a book club or something else that can be ignored as "safe." (Everybody arm himself with a copy of A Wrinkle in Time.) On a side note, unless you know some librarians, you might be surprised the things a lot of them do on weekends. —Christian Campbell 18:19, 23 May 2008 (UTC)

How close do you have to get to have achieved a location? The location for me today is ending up in the middle of a field of wheat. Would the nearest field boundary be acceptable? Or the nearest public access point?

Many States and Counties have an online GIS system that allows you to lookup more than just an areal photo of the land, like who owns it, for example. I suggest people look into this before heading for a location to make a more informed decision about whether and how far to proceed. Example in Charlotte, North_Carolina . WokTiny 22:56, 23 May 2008 (UTC)

Radio Frequency Standard

How about coming up with a frequency standard that we can use with two-way radios? Then anyone in the vicinity can announce their arrival and meet with the others nearby. --waq

Agreed. This way, nobody should feel the need that they have to trespass. Obviously, in any case, you'll still have people who will try, but at least you can mitigate the possibility.

Only potential problem is for the non-Saturdays, who's to say when anyone will show up? 16:00 local time is only the standard for Saturdays. On a Monday, someone could go at 12:00, announce his (near) arrival via radio, and no one would answer. That wouldn't stop anyone from trespassing alone at 20:00. --Tim P 19:17, 23 May 2008 (UTC)

BTW, I suggest FRS Channel 6, if for no other reason than the comic number ends in '6'. --Tim P 19:19, 23 May 2008 (UTC)

Agreed. I formally propose that FRS Channel 6 (US) and PMR446 Channel 6 (Europe) be made the official xkcd geohashing radio communication standards. Waq 12:26, 24 May 2008 (UTC)

Split Cities

I have created a Split Cities category (temporarily?) for cities such as Chicago and Washington, DC, which don't quite fit squarely into a graticule. It's just a way to categorize them, not a proposed solution to the problem (hell, it's even debatable whether there is a problem). Feedback? Tyler 02:05, 22 May 2008 (UTC)

I think the alternative i've coded up should solve this problem as well. Check it out: Alternative Geohash

In the event of a split city, I think the simplest solution is for people to go to the nearest location. If you live in the north half of a split city, and the point of the day is far north, just try the point in the graticule directly south, where the point is probably within the south urban area of your city. no? WokTiny 15:46, 22 May 2008 (UTC)

No city can possible have it worse that Columbus, Ohio: split into four exactly in the center. Tytrain 01:04, 23 May 2008 (UTC)

In Sydney we've solved this problem by making it officially whichever one is closest to the CBD. If there's any contention, it's xkcd rules - whoever posted first is correct. Gormster 15:35, 23 May 2008 (UTC)

Achievements

I made an Achievements page to list some extra challenges that can be achieved so people can brag about some of the harder places they've gotten to (eg, i've got a Water GeoHash achievement when me and a friend hired a boat and went to the location on water). I thought of a few, but needless to say there are quite a few possibilities. zorg

New award?

So, I discovered I can see the point from my backyard. Is there an award for that? 2008-05-24 40 -111 McKay 18:27, 24 May 2008 (UTC)

Another achievement

How many points can you reach (in different graticules) in one day? Would require some luck, but it would be an awesome achievement / high score page. Or a different variation- choose a time frame (say a week 1 year ago) and visit all of the points from that time frame in as short a time period as possible. Thoughts? 70.162.29.88 22:58, 24 May 2008 (UTC)

Facebook

It was inevitable, because I am a Facebook whore: Geohashing on Facebook I might start work on an app after I finish my current one. Gormster 12:51, 22 May 2008 (UTC)

There are also some local groups. So far, I know of: Geohash - Toronto, IVSLO Geohashers (Southern Cal somewhere?), and Geohash - Denver (which I created, for the record). --Doubt 21:00, 22 May 2008 (UTC)

I've also created Oklahoma City Geohashers. Trvsdrlng 19:51, 24 May 2008 (UTC)

Use of one degree grid sucks

The usage of integer lat/long as the grid for this is really simple but it doesn't perform well. For example, the DC metro area is split into four zones each which contain a small populated area and a large area no one wants to travel to. Alternatively, consider Milwaukee Wi, where there is a 80% chance of the meeting location being in the middle of Lake Michigan, likewise for a number of other coastal cities.

Instead what should be done is someone should search for a tessellation of the world where each tile has the same area as a 1deg/1deg grid but optimized on the following criteria:

• Tiles should not span national borders.
• Where the boundary lines avoid areas of large population
• Tiles should not simultaneously contain large amount of water and non-trivial numbers of people
• Any others?

Once a tessellation is found the hashing could just be an index into each tile. It would be somewhat more complex, and require knowing the tessellation, but it's not like anyone is doing MD5 in their heads.

Perhaps a contest could be held for tessilations? People could compute ones then argue why theirs were the best. ;) --Gmaxwell 22:01, 22 May 2008 (UTC)

People don't want to travel there? I wouldn't be quite so sure about that. Geocaching is rather popular in large foresty areas, and the visited hashes we've seen so far were busy enough even though they were in the middle of nowhere. I actually see your point, but I think that it's not possible to create anything better than this which isn't particularly difficult or annoying to implement. As for the national borders - I'm fairly happy that's not too much of an issue here in Europe ;) Nazgjunk 22:07, 22 May 2008 (UTC)

At least you can expect find something at a geocache. Seems to me that the value of a geohash is meeting the other hashers. When the selected location is often multi-hour drive (due to geographic features and lacking roads) into an unpopulated area it's likely that no one will show. So people will lose interest and be aware of it the few times it is in a good location. With something around 300 geocaches found I think I've only run into other geocachers three or four times or so, and most geocaches are in locations far less random than geohash locations.

I think the people who will spend hours getting to an adverse location will really enjoy the conversations they'll have on the days when they do run into someone. And I think you may be underestimating just how geeky xkcd readers may be -- to me the adverse locations sound most attractive. For those who'll go only when "it is in a good location," there's still the joy of the hangfire of not knowing when that will be until just beforehand. I like the idea of multiple people having determined in their heads to partake in an adventure of unknown complexity, even subject to whatever personal qualifications, where the fruit of the mutual determination doesn't materialise until the adverturers converge on the target. Lastly, I guess geocaching doesn't have any goal of meeting others, and wallclock time is not part of the target, so it doesn't sound surprising you'd rarely run into others? —Christian Campbell 17:27, 23 May 2008 (UTC)

Even when crossing borders is easy, differences in available data might lead to different tessellation rules. I know where to get good population data for the US, but I don't personally know how to get the same data for Mexico.  :)

As far as complexity goes.. geohashing already requires an MD5 .. is indexing into a big table of polygons that much harder?  :) (though the MD5 should be dropped.. if the random seed is random enough, just xoring the digits should be more than random enough...) --Gmaxwell 22:24, 22 May 2008 (UTC)

No one claims the DJIA is very random. But with the MD5, even the slightest change produces a completely new point. That's why I'd argue the MD5 should never be dropped. Zigdon 23:57, 22 May 2008 (UTC)

In Europe, meeting with people from other countries only makes it more fun. Integer grids are good, you can always go to another graticule if it's closer. Nobody says you should take your home's location, you can travel to another location and take the geohash there. --FrederikVds 13:56, 23 May 2008 (UTC)

You're missing the point. See Lowman's post below. Gormster 15:33, 23 May 2008 (UTC)

I don't think so. Maybe you understood me wrong. What part of the point am I missing? --FrederikVds 17:33, 23 May 2008 (UTC)

iPhone Implementation

Last night I finished a rough implementation of this to the iPhone 2.0 Beta SDK. Right now it uses your current location and date and then does the math, then gives you a map with the destination address along with directions to there from where you are at. This will be even more useful if the next 3G iPhone come with GPS, until then it uses it's less accurate cellular and wifi location tools to locate you. I plan on adding a way to select your date and your desired graticule as well. Eventually I'll also investigate filtering of the results in watery areas. I can't distribute it currently, but as soon as I can I'll make it available. -- Shakedown

Saturday's meetingpoint

I was wondering. Is the saturdaymeetingpoint calculated with the date of saturday and the dow opening of friday? Or is the date you use always the date of the dow opening? --Evo-- 13:22, 23 May 2008 (UTC)

My understanding is that you hash in Saturday's date, so that the locations for Fri, Sat & Sun are all different, and are available at 09:30 EDT on Friday. Speaking of which, could someone post the Saturday location? I don't have a hasher. AshleyMorton 13:40, 23 May 2008 (UTC)

Yes, that's right... Current date, most recent DOW opening. Speaking of the hasher/locator, is anyone else having trouble with the peeron one? everytime I hit update it jumps the point around a couple times. I'm at a loss for where I'm supposed to go. --WokTiny 14:06, 23 May 2008 (UTC)

For some reason it adds a few zeros to the Dow Jones every time you click calculate, screwing up the algorithm. StJimmy 14:22, 23 May 2008 (UTC)

I'm not seeing this. Steps to reproduce the problem, or is it fixed? --Xkcd 16:40, 23 May 2008 (UTC)Xkcd

I'm still seeing this. Just go to the page in Internet Explorer and either move the map, zoom, or hit the "Update" button again. The coordinates and the marker will change. The bug doesn't show up in Firefox but it does in IE7, I don't know about other versions of IE.--Ahecht 18:37, 23 May 2008 (UTC)

Atom Feed

I noticed yesterday that before the stock exchange data becomes available, the atom feed creates a kind of 'intemediary' geohash using todays date and yesterday's data. This might be intentional, but personally I find that undesirable on weekdays. Could it be modified to show yesterday's date and geohash until data is available? Nicktaylor 14:04, 23 May 2008 (UTC)

I'm currently working on getting an alternative Atom Feed implementation ready for public use (although I think I'm going to wait until the Time Zone issue is resolved). Mine will only update at 09:40 Eastern daily (accounting for DST changes), and uses the irc.peeron.com source for the DJIA, which is updated at 09:35.

I will certainly post it here when it's done, so stay tuned. --Tim P 20:10, 23 May 2008 (UTC)

The time zone issue has been resolved with the 30W Time Zone Rule. I'll continue to work on getting my implementation ready. --Tim P 04:34, 24 May 2008 (UTC)

Flags

Did you ever watch The Amazing Race? They had red and yellow flags and arrows to signify that there was something to do with the race nearby. Red and yellow were their colours. I'd suggest a similar two-colour pairing so that fellow geohashers can easily find each other at the marker. I'm gonna suggest blue and green, because, you know, geo. Gormster 15:43, 23 May 2008 (UTC)

Except that blue and green would blend in with the scenery? --WokTiny 15:47, 23 May 2008

Won't be liking that choice (i.e. blue and green) during the hunting season on a MNIMB Geohash. --KDinCT 16:12, 23 May 2008 (UTC)

 ??? I'm confused. Gormster 00:29, 24 May 2008 (UTC)

How about brown and khaki -- and antler hats? --Ahecht 16:56, 23 May 2008 (UTC)

Um, who would be cleaning up all these flags from all over the world? I don't think we want to be littering quite that much? Zigdon 17:48, 23 May 2008 (UTC)

If you need flags for anything, they make a biodegradable flagging tape for just this sort of reason. Geocaching sometimes uses it to signify things during day-long events. If it gets left behind it's no big deal that way. 155.41.240.238 18:55, 23 May 2008 (UTC)

Okay, when I said flags I didn't mean literally flags. I meant something to alert others to your presence. It can be anything, paint, tape, as long as it's those two colours. Gormster 00:29, 24 May 2008 (UTC)

World map

The Active Graticules page is getting too big, so I was thinking about making a world map, linking to the graticule pages. I'm trying though I don't know if it's easy.--FrederikVds 16:03, 23 May 2008 (UTC)

Amen to the Active Graticules page getting too big. I too was trying to think if there was a visual way to lay it all out. Or a way to break it up so it isn't such a huge list. But then again if all of the graticule pages are properly categorized with countries (and states) the category page will help locating graticules much easier. I will be interested to see what you come up with. --KDinCT 16:10, 23 May 2008 (UTC)

The code will probably be something like Template:Worldmap, only the wiki doesn't seem to let me use <script> tags for obvious reasons. I was also thinking about using an iframe, but it doesn't let me use that either. How is it done for the <map> tag? --FrederikVds 16:36, 23 May 2008 (UTC)

The <map> tag is an extension I wrote to the wiki. Would a link from the map tool itself to the appropriate wiki page be useful? Zigdon 17:49, 23 May 2008 (UTC)

I'm not sure what you mean. My basic idea was a big world map (Google Maps) with all active graticules surrounded by a red rectangle, and clickable. Maybe you can extend your map tag to do that?

Edit: I tried if it's possible using a static map image and a table, but that's too hard. --FrederikVds 19:10, 23 May 2008 (UTC)

The new version of the map page (which should go online tonight) includes links to active graticules. It doesn't make it obvious where they exist - I'll see if I can generate a gmaps overlay to make browsing easy. Zigdon 03:01, 24 May 2008 (UTC)

Missing Historical Data

There is a good chance that no one cares, but the reference Geohashing Coordinate Calculator will not work for several valid dates. I think some just havent been copied from the previous day, but some may have just been missed. I've put a list of those dates up, delete it if you'd like. --ZorMonkey 14:20, 24 May 2008 (UTC)

How to recognize each other?

There should be some distinctive sign for geohashers so they can distinguish fellow geohashers from people that are just passing by. The problem is, if you just start asking random people "are you geohashing?" you are going to make a fool of yourself, but on the other hand, if you spend an hour standing without moving in a weird place looking particularly weird, you are also quite likely to make a fool of yourself. So this sign should be obvious enough so that geohashers would immediately recognize it, but at the same time discrete enough so as not to draw attention of other people. --Ilia 20:30, 24 May 2008 (UTC)

Keep an eye on #Radio Frequency Standard on this page; ideas are being discussed. --Tim P 23:10, 24 May 2008 (UTC)

Buy an xkcd shirt, and wear it on your geohashing trips? 71.34.59.134 03:42, 25 May 2008 (UTC)