Macronencer/Journal Archive 2009

From Geohashing

Macronencer Journal Entries (2009)


2009-07-17 Couch Potato...
I have just worked out that at my latitude of 50 degrees, assuming my house includes its land area of about 30x40m, there is a 1 in 6.7 million chance of getting a couch potato award on a given day. Not good odds, though admittedly a little better than the Lotto jackpot :|

2009-07-29 More about Couch Potato
I think my previous estimate was pessimistic. Personally I would count anything within a 30m radius of the centre of my house, given that the grounds are fairly large. Actually they are rectangular, but likely to be equivalent to a 30m radius circle. I must measure this accurately at some point.

Anyway, this new criterion yields a 1 in 3 million chance on a given day (equating to a 1 in 8200 chance in a given year).

2009-07-30 How accurate are the co-ordinates?
I like to answer questions like this, so I had a go. By my reckoning, the geohash algorithm gives a maximum grid resolution of about 6 femtometres, which is about 6,000 times smaller than a hydrogen atom. Talk about a hammer to crack a nut!


2009-08-01 Kayaks!
I went looking at water transport today. I seem to have these options:

1. Solid sit-on kayak
Pro Less work paddling against the wind, more rugged for larger stretches of water, can get a larger version and sit my son in the back seat. Andark's even told me it might fit IN my car, removing the need for a roof rack. I'm going back there to try doing that tomorrow, though I don't plan to buy anything just yet.
Con Expensive. Too large to take on bike-only expeditions, and I will get wet (but hey, that was probably going to happen anyway with a water hash)
2. Inflatable
Pro Cheap. Small enough to go in a bike trailer. I could probably get bike, trailer and boat into my car for maximum Ninja-strike capability.
Con Hard work to paddle against wind, and slightly more limited in choice of water. Probably dangerous in large tidal rivers, and NO WAY I would take one on the sea, of course.

This is interesting. The inflatable is cheap enough that I could get one and get the solid kayak later as well. This would allow me at least to have some water capability in the mean time. I also want to get some kayaking lessons (I need a refresher!)

2009-08-02 More about boats...
I cycled over to Hamble Canoe Club today and spoke to them about my plans. Alex was very helpful, and told me about this wonderful thing called a Tote-n-boat. It looks perfect! It could go in the car, or behind my bike in a trailer very easily. Were I fitter, I might even be able to sling it over my back while cycling, but I have my doubts about that. There's even a sailing rig for it, should I ever feel the need for such a thing. I wonder whether there's a UK supplier...

2009-08-04 Bigness
64,800 graticules... think about that. I just did. Even if you did one every single day, in the biggest Consecutive geohash ever, it would take 177 years. Even if you didn't bother with the ones that are in the sea, you're looking at decades of travel.
And when you remember that it would take most of an entire day to walk non-stop from the North end of a grat to the South end, you begin to understand the size of the Earth.
The Earth, of course, is just a small planet orbiting a star. The best estimate we have for the number of stars in the known universe is a very large number. So large that if you counted 3,000,000,000 stars every second (roughly the current clock speed of a home computer), you would take a whole CENTURY to count them all.

Feel small yet?

I see a distant future, in which latitude and longitude have been replaced by galactic co-ordinates, GPS units by some sub-ether positioning system with tweaks for relativistic issues such as the simultaneity conflict, the DJIA by some other source of stochastic nutrition (who knows what?)... how long would we have to live to hash every planet on every star in every galaxy?

I told you: I think big. I see no reason to think small.

2009-08-05 New GPS
My Garmin eTrex Vista HCx arrived today from eBay. Seems very nice! Robust, and waterproof (IPX7, which I think means up to 1m of water) - however, I'm sure it doesn't float so if I get my boat, I'll also be getting a plastic sealable pouch with attached buoyancy device to prevent anguish. The software is adequate, but could be more exciting. As for the price of the maps...! Bloody hell. The UK TOPO map costs more than the device, aat a nice $299.99 or €230. Won't be buying that in a hurry. I think it would be nice if you could buy small sections of the maps, like with the old OS maps of Britain - they were not cheap, but at least you could go somewhere where you needed to buy maybe three of them, and it wouldn't break the bank. Anyway, it's good enough for hashing, without detailed maps, so I'm still happy. Also just downloaded the Goecaching app for my iPhone. I will try it out this weekend, perhaps.

2009-08-23 Missed it!
Bah! I was ferrying my son back his mum's place today, and in doing so I had about 4 graticules potentially accessible from the journey - two of which were unexplored by me. You would have thought that, with two days' notice, I'd have managed one hash! But no. They were all either too far from the route or clearly in inaccessible land (e.g. slap bang in a field with a farm building very close by). Curses! This will surely delight my evil twin brother, Thaddeus...

2009-08-27 Folding Huge Tracts o' Land
A thought experiment: Iterate through all the graticules that cover your country. Take the average hue, saturation and luminance values of the the various graticules for each pixel, according to a map of your choice (e.g. Google satellite). What you've done is kind of fold the country on top of itself by treating all graticules as geographically equivalent, and the result might be interesting. For a given day's co-ordinates, for example, if it lands in a grey area it's probably going to indicate that there is a variety of terrain represented around the country. If it is blue, there's a good chance that many of them are on water - etc. I thought of this today when I was clicking around on peeron's hash tool. I noticed that two of the points were quite close to golf courses... now, we just need a map showing just the regions that are in golf courses (black) or within a certain distance of one (fading to white). Or the same for pubs, parks, etc. This would enable an instant analysis on a given day - showing, for a given set of graticules, what kind of probability sum results from adding the individual distance functions. If the point is in a very dark region, something wonderful has happened (for example, every hash in your country is near a pub) - if it's white, there's nothing of interest near any of the graticule points.
Wow, that was quite a stream of consciousness. Sorry, I'm feeling creative.

Not mine though :) Incredible events this weekend. On Friday afternoon I looked at Sat Sun and Mon to scout the local graticules for possible trips (Monday being a holiday here in the UK). Everything was either clearly on private land or too far away. Bit of a downer. Then Sermoa contacted me to say that Sunday's Swindon grat location is actually next to the wall of the building where she works! This is AWESOME! It's as if she's won the lottery :) So, although I am at work tomorrow, I will definitely be away early and get up there for 4pm to celebrate with her. Literally a chance in millions - incredible.


2009-09-11 Some Random Thoughts
It's been an interesting couple of weeks. The first cubicle geohash was followed by my first drag-along, my first Consolation prize (and associated pulled abdominal from cycling) and then my first midnight geohash with Sermoa and Mapaholic. Just yesterday I realized that Mouse Over Day is the same day as my parents' wedding anniversary - and next year it is their 50th one. Well, with any luck the party will be on the Saturday the next day, so I'll be able to do my obligatory hash on the Friday, the actual day. If not, I'll visit one on the way to see them in Norfolk.
Geohashing serves one fundamental purpose - it provides an objective. We do the rest.

2009-09-15 Globalhash mirrors
The Globalhash concept is like having the same lottery numbers every week, in one sense: it is so unlikely that your neighbourhood will come up, that you feel you have to check it every single day, for fear of kicking yourself later that you missed one you could have done. This got me thinking today. Every graticule must have a special region in it, which I will call the "Globalhash mirror". If a standard daily hash point falls within this region, then it also means that the Globalhash for that day has fallen in that graticule. This is true East of W30, but West of W30 one would have to remember that the Globalhash will be a day behind the standard hash because Globalhashes always use W30 co-ordinates.

Anyway, the Globalhash mirror region can be calculated easily from your latitude and longitude. It is a "trigonometric rectangle" (i.e. bounded by latitudes and meridians) with two opposite corners defined thus:

GMLAT1 = ( 181 * HOMELAT + 90 ) / 180
GMLON1 = ( 361 * HOMELON + 180 ) / 360

GMLAT2 = ( 181 * HOMELAT + 91 ) / 180
GMLON2 = ( 361 * HOMELON + 181 ) / 360

...where HOMELAT and HOMELON are the absolute values of your graticule's integer co-ordinates. After calculating, you have to re-apply the correct sign. This makes the floor/round issue go away :)

For my graticule (50 -1) these work out to:

GM1 = ( 50.77777778, -1.50277778 )
GM2 = ( 50.78333333, -1.50555556 )

By plotting these on Google Maps (GM1 and GM2), I can find out the "rectangle" of land to watch. If a hash point lands in there, I know that the Global hash for that day will also be in my graticule :) If you look at those two points on Google Maps and compare them, you'll see that it's an extremely small strip of land. This just goes to show how unlikely it is that the Globalhash will fall in your graticule: in fact, in a given year, the odds would be around 1 in 178, so if you're waiting for it, better be prepared to die first! To Globalhash, one has to travel :)