MySQL offers ENVELOPE() to find the minimum bounding rectangle of a geometric object.

The result is a polygon with four segments, defined by five points. It took me a while to make sense of it, partially because the only documentation that I’ve run across so far for POLYGON() syntax is in the ENVELOPE() function mentioned above. I also had to draw a picture to think it through.

They write this: POLYGON(( MINX MINY, MAXX MINY, MAXX MAXY, MINX MAXY, MINX MINY )), I think this (in pseudocode-ish form): POLYGON(( $point_a, $point_b, $point_c, $point_d, $point_a )), with the $point_s corresponding to the diagram.

It’s MySQL spatial data week here, though I am spreading out the posts to, um, ease the pain (or boredom). Anyway, here are some commands/functions I don’t want to forget about later:

Start with an existing table called geometry, add a spatial column and index it:

ALTER TABLE geometry ADD coord POINT NOT NULL;
CREATE SPATIAL INDEX coord ON geometry (coord);

Insert some data; think in terms of POINT(X Y) or POINT(lat lon):

INSERT INTO geometry (coord) VALUES( GeomFromText( 'POINT(40 -100)' ));
INSERT INTO geometry (coord) VALUES( GeomFromText( 'POINT(1 1)' ));

Get those X,Y coordinates back from the table:

SELECT X(coord), Y(coord) FROM geometry

Get points within a bounding rectangle:

SELECT MBRContains(
	GeomFromText( 'POLYGON((0 0,0 3,3 3,3 0,0 0))' ),
	coord
)
FROM geometry

MySQL has some powerful, and perhaps underused spatial extensions, but the most interesting functions are still unimplemented: “Note: Currently, MySQL does not implement these functions…”

Among those as-yet unimplemented functions is DISTANCE(). Alternatives can be found here and here, though neither is clean or simple. I wonder if a simple MBRContains() is good enough, though…

Plazes, a kinda-cool, formerly networked-based geolocation tool has just been revamped. They’ve been promoting this change for over a month (I got a cool invite to the launch party, but couldn’t make the flight to Germany), and they’re continuing the push now that it’s live. I’ve used the new service for a few days, the company has sent me an email soliciting feedback, I’m offering it.

I submitted the following via the site’s Contact form, but the message seems to have disappeared, and I prefer public discussion, so I’m reprinting it here:

I like a lot of the new Plazes, but…

All my previously “unknown” Plazes got re-assigned to Heidelberg. Some of those unknown Plazes are truly unknown, but I usually try to go back and fill in the details of a location after the fact (if not in-situ). Now it looks like I can’t (and I won’t get discoverer’s credit (thinking of that, do “discoverers” still get credit in the new system?)).

Also, I can’t figure out how to get an RSS/Atom feed of my movements. It was easy in the old site, but not now, and I’m finally getting interested in using that data in my blog.

The new Plazer app (Mac OS X) is prettier, but the big feature for me is automatically updating my current Plaze wherever I go. I just found a preferences option for that and I’m hoping it does what I expect.

The SMS features are cool, but it took me a while to find the instructions on how to use them. They’re not linked in the Tools tab, and it took me a while to find the Help link and look there.

Finally, a more philosophical question, Plazes seems to be de-emphasizing network-based location and discovery. Is there a story there?

Thank you,

Casey

[tags]plazes, geolocation, customer relations, product feedback[/tags]

In yet more geolocation news, beermapping.com’s maps to breweries will make my travel planning easier, and my travels boozier.

Hey, it’s casual Friday, take off early and go find a new brewpub for lunch.

beermapping.com, brew maps, breweries, brewery, brewpub, casual friday, geolocation, mapping, maps

Wearing the badge “still beta,” Plazes, the free, network-based geolocation service, now sports a new coat of paint. Among the improvements is the Flash-based badge (above) and a much improved frontpage/dashboard that combines the map of known locations with the map of active users, formerly two separate screens.

On the downside, I sort of miss the old tracker. I love the icons on the new one, but there was a simplicity to the old list of recent plazes and favorite plazes that I liked. Also missing is the ability to display a time-range; instead, it simply displays the locations in date order. What I really want back is the ability to see, in one screen, all the places I’ve been in the past year, or month, or whatever (yeah, as Tim notes, it’s a bit exhibitionist, but…). Still, the new Plazes does add “hangouts,” which is sort of cool, you know, as a stalking aid.

The final downer is the useless of the “My World” map. It’s not that it shows I’ve only visited 1% of the world, it’s that it suggests I’ve visited all of the US — including Alaska and Hawaii. The map might be gratifying for the European developers, but I’d like more granularity.

Still, I continue to run the Plazer, and continue to look for new plazes to claim.

beta, geolocation, gis, location aware, mapping, plazes, still beta

Engadget alerted me to this GPS data logger from Spark Fun Electronics.

The device records up to 440 hours of data to a 256MB SD card in either a simple text file or KML-compatible format that you can display in Google Earth.

I like it, I want one (actually, I want three, and I’ll eventually post about why), but the ad copy tweaked me a bit:

Pull the SD card, insert it into a card reader, [...] and wammo–you can see what Casey did over lunch with a satellite image overlay. Take a look at the example screen shot. You can see what lane Casey was in! When he stopped at the light, his data points piled up. Fancy. Real fancy. Speed is also datalogged – it’s like Big Brother in the palm of your hand…

electronics, engadget, geolocation, GPS, gps data logger, kit, location tracking, Spark Fun Electronics

This post started with Ryan sending me this link demonstrating a KML overlay of county borders of his bifurcated state in Google Maps.

Then I found this Roundup of Google’s Geo Developer Day (btw, I so wanted to be at Where 2.0) with tales of the new geocoding feature of the Google Maps API, more details about KML-in-Google-Maps, geotagging in Picasa, and the new Google Earth 4.0 beta.

And somewhere along the line, I ran across a link to SketchUp, Google’s 3-D modeler that seems built especially to put dimensional structures in Google Earth.

geocoding, geographic information systems, geolocation, geotagging, gis, google earth, google maps, kml, sketchup, where 2.0, where20

Here’s an interesting GeoPlace.com article on open source GIS tools, including GIS extensions to PosgreSQL and MySQL. Via The Map Room.

tags: geo world, geocode, geocoding, geographic information system, geography, geolocation, gis, gis development, gis guide, gis tools, map room, mapping, mysql, open source, open source gis, open source tools

I’m a big fan of the WP Geo plugin, but I want more.

My biggest complaint is that I want to insert coordinates using Google Maps or MultiMap URLs, rather than insert them in the modified story editor. So I wrote a bit of code that reads through the URLs in a post, finds the “maps.google” or “multimap.com” URLs, fishes the latitude and longitude out of them, and adds some geocoding tags to the body of the post.

Take a look at how it works with these posts in my archive…

You should see one or more blocks of links like the following (from my Osceola Weekend post):

geolocation: geo:lat=44.006336, geo:lon=-71.547260, geotagged, geolocation:44.006336,-71.547260 geobloggers

Go ahead and click the “geobloggers” link. I could have added these links using the old Geo plugin, but I still would have had to insert the coordinates separately. Actually, that brings up a good point: my code also inserts post metadata in the same format the Geo plugin uses, so I can take advantage of all the good functions it has, like the one that inserts the “<meta name=“ICBM” content=“44.006336, -71.547260” />” tag in the header of this post (caveat: I had to disable the add_action code in Geo that feeds the postmeta table, as it was conflicting my code).

I’m releasing this now, to start some public discussion, but please recognize that it’s a very early beta.

Download: bsuite_geocode.zip
Install: place unzipped “bsuite_geocode.php” file in your wp-content/plugins folder and activate it via the WP control panel. See the WordPress Codex for more detail.
Use: write posts as usual, adding links to Google Maps or MultiMap as appropriate. Links to those sites that have latitude and longitude components will be used to geocode the post.

Example of a working URL:

http://maps.google.com/maps?ll=19.355507,-155.072365&spn=.191780,.318003&t=k&hl=en

Example of a URL that won’t work (note how there’s no “ll=”):

http://maps.google.com/maps?q=decker+canyon+rd,+malibu+california&spn=0.019857,0.039750&hl=en

I’ve got a lot of features and uses in mind, so consider this only a start. Please post bugs and suggestions in the comments.

Also, see these previous posts on geolocating the news or geolocating everything or just search the archives to understand why I’m so excited about things like this.

tags: beta, blog, blogmap, blogmaps, blog gis, geo, geocoding, geolocation, geotagging, gis, google maps, lat, latitude and longitude, lon, map, maps, mapping, metadata, multimap, plugin, plugins, wordpress, wordpress plugin, wp plugin

Old news from Gizmodo and Wi-Fi Networking News (quoting WiFi NN):

Skyhook has assembled a database of information about 1.5 million access points across 25 major cities in the U.S. by driving every street in every city. Their software records multiple data points per sample for directionality. Fire up their software on a laptop, and it compares the Wi-Fi information it sees with what’s in the Skyhook database, popping out a latitude and longitude within 20 to 40 meters.

Also geolocation related: Monopoly Live: London style.

tags: access points, geolocation, gps, mapping, monopoly, skyhook, wifi

Who doesn’t love tagging? No, tagging as in annotating, not graffiti. Anyway, Rixome is the latest among a bunch of plans/projects to enable tagging of geographic spaces/real-life environments.

The good people at We Make Money Not Art had this in their post:

rixome is a network and a tool that turns mobile screens into windows that show the virtual and public dimensions of our point of view.

A walker (a rixome user) can see on his/her mobile phone/PDA/laptop screen the virtual interventions that have been added to the location where s/he now stands. For example, a spoken message can be left on a given location for other “walkers” to hear through headphones whenever they pass by. The message can also be written, or it can be a 3D animation or image, a photography, a drawing, a video.

Remote rixome users can also check vía Internet the traces left by others but s/he won’t be able to add an intervention similar to those published in situ.

Developed by gelo for his at Master of Art and New Technologlies at the Universidad Europea de Madrid.

(Engadget is onto this story too)

This idea isn’t new (see Twenty Years From Now: Urban tagging and New Media Knowledge – GeoTagging The City) But time, technology, and a forward thinking art student make Rixome look more plausible than the others.

Related: previously at MaisonBisson: Geolocating The News, When You Don’t Have A GPS, and anything else about geolocation. Interesting websites: Urban Tapestries | Social Tapestries and Gelo.tv. Books: The Wisdom of Crowds and Smart Mobs.

art student, folksonomy, forward thinking, geography, geolocation, geotag, geotagging, laptop screen, mobile, mobile phone, new media, pda, public dimensions, social environments, spoken message, tag, tagged environments, tagging, tags, urban environments

Last week I got excited about the as-yet unreleased geolocation API for BBC Backstage. Now Larry D. Larsen of the Poynter Institute is excited too. In a post titled The Future of News (… Hint: GPS) he talks about putting news in geographic context with geolocation tags.

Eventually, clicking an article in a news/Google Map hybrid might zoom in to a 3D model of the area where an automatic pop-up starts playing a slideshow with pictures of the scene or streaming video along with the text news content. Imagine integrating Google Maps into your classifieds so readers could search for jobs based on what is close to their house. The possibilities are endless.

It’s aparently an old saw of his, but I hope his message starts to get through.

Credit goes to Ernie Miller for the blinking this at The Importance Of….

Technorati Tags: api, bbc, future of news, geolocation, gps, news, poynter institute, reported

Geolocation by GPS my be the most straightforward approach, but we mustn’t forget the other ways to get lat/lon coordinates.

All current cell phones support aGPS positioning to comply with federal E-911 mandates, but not all phones make it easy for the user to get that information out of them. Still, some do and GPS-enabled moblogging is becoming common in Asia and Europe, and there’s at least a public proof of concept going in the US.

Then there’s ethernet/WiFi. Plazes is a kind of social networking application that allows users identify their location based on their network fingerprint. Using the assumption that networks are typically stationary, Plazes then associates lat/lon coordinates to that network based on information submitted by user who ‘discovered’ the network. Plazes’ real trick, however, is to show me who else is online nearby. Problem is, I live and work in New Hampshire where I appear to be the only user online north of Virginia.

But the Plazes folks didn’t invent the concept of using network information to identify location. If I wasn’t so lazy I’d find the story I read a couple of years ago that mentioned it, but this June 2004 article in New Scientist tells the story of one such effort: PlaceLab (extra coverage at Engadget and ExtremeGPS). A Google search turned up Herecast and now Engadget is reporting on AllwaysOnGPS, a replacement GPS driver (for Windows PCs) that mixes GPS and WiFi derived location data to provide the most accurate info despite changing coverage.

Finally, one of my favorite solutions is to use Earthcomber in manual mode. The Palm application allows you to scroll around a map and mark locations as though they were waypoints in a GPS. And though that’s neat, it’s the mapping features that make it a winner. It’s far better than those lousy tourist guides in cities. I used to go to AAA for maps and guides in preparation for a trip, but now I check Earthcomber for area maps and updates.

Technorati Tags: agps, cell phone, coordinates, geolocation, gps, lattitude, longitude, map, mapping, maps, moblogging, network, networking application, palm, picture phone, social networking, wifi

The APIs aren’t yet out, but the BBC has already won me over with their Backstage BBC concept. Of course, I’m a fan of anything with an API, but the real deal here is that it appears they’re planning on releasing a “query by geo-location data” API — and I’m all a gaga about about geolocation. I’ll definitely be looking to see what takes shape across the pond.

Technorati Tags: api, backstage, backstage.bbc, backstage.bbc.co.uk, bbc, bbc backstage, geolocation, news

A an old John Udell piece at InfoWorld hints at GeoURLs, but the GoeURL site is down, and has been for a while. The concept sounds interesting: you mark pages with coordinates, then use GIS to map those pages to geographic locations, finding pages and people of interest along the way.

To join GeoURL, you add this kind of metadata to your homepage:

<META name=“ICBM” content=“42.93564,-72.27239”>
<META name=“DC.title” content=“Jon Udell”>

I got interested in this sort of thing (geolocation) a while back, and I haven’t quite given up.

Update: Bjørn is right, GeoURL is back and I should have updated this post ages ago. Look here for more about geolocation on MaisonBisson. …And Bjørn’s website is worth a look too.

Technorati Tags: geographic, geolocation, gis, map, metadata, semantic web