Zmarties

As well as Google, Yahoo have also launched a mapping API. Whilst the Google API has it's fair share of problems, the Yahoo API is quite simple - it's such a shame that the service is such a poor one, so as to make the API a non starter as far as I'm concerned.

Jeffrey McManus (who works at Yahoo) has a 7 point list as to why he thinks the Yahoo API is better than Google's, which comes down to this:

1. The Yahoo map is hosted on Yahoo - so this means that you can't integrate it into your site - what good is that?
   
2. Yahoo allows unlimited maps to be served up - whereas Google have a limit of 50K per day per page - that seems very generous to me
   
3. {juvenile name calling}
4. Yahoo allows US street addresses as well as the Lat/Long that Google uses - but Google's maps are worldwide, whereas Yahoo is limited to the USA only
5. {repeat of juvenile humour}
6. Yahoo have lots of other API's for other types of data - agreed - I'm a big fan of their other API's (which pass back data you can then serve up presented as you want), but that only serves to show how poor the Yahoo mapping API is
7. Yahoo uses modified RSS to specify points to show on the map - agreed this is currently simpler than Google's arrangement

So by my reckoning, there are 2 strikes against the Yahoo API here - the maps can't be embedded, and are USA only, with only the simplicity factor in their favour. I really can't see many people wanting to use this API at all.

Google Maps has finally gained an official API, (though being beta, it's almost as likely to change as the unofficial API everyone has been using up to now).

Use of the API requires a key, which is causing no end of problems, since keys are tied to partial URLs:

• you cant get a single key that works across more than one of example.com, www.example.com, example.co.uk
• you cant get a single key that works when your page is migrated from example.com/news.htm to example.com/archive/june.htm
• if your site uses URLs of the form example.com/tag/page.htm where tag varies, then you need a separate key per tag.

Lets hope they fix that ASAP, since thats a huge flaw in the implementation.

There's a very lively discussion group for the API, with lots of good questions, answers, and examples being posted already. A few that caught my eye are:

• discussion on how to add a scale bar to the maps
• calculating the distance between two points
• scaling items with the zoom level
• adding a side panel to the maps

Example uses of the API include

• MapMaker which allows you to interactively add a path overlay to a map
• Paris Star Forts which illustrates adding a side panel

Other interesting items to come out of the discussions:

• geocoder.us which can translate addresses to latitude/longitude
  

A few more Google Maps data presentations:

• gCensus presenting US census data
• zoto photo sharing placing geotagged photos on the maps
• gTraffic.info providing UK-wide traffic info, plus traffic cams in central London
• dynamite local providing access to a lot of UK datasets, including weather, flickr photos, travel info, geocaches
  

Getty Images are indicating that their search now uses "smart commas". The text describing this feature notes that:

If you're using words in the search field for your keyword searches, commas now work like AND:
- Put "tom cruise, close-up" in the search field
- Your results will return images that contain close-ups of Tom Cruise

If you're using image numbers in the search field for your keyword searches, commas now work like OR:
- Put "1945157, 1951923" in the search field
- Your results will return both image # 1945157 and image # 1951923

I approve of this - this seems a very sensible behaviour. However, the text also notes that:

You can also use an ampersand (&) in place of AND. But be sure to add a space between keywords and "&".

I don't understand this restriction at all - the examples show that you dont need to surround a comma by spaces, but you do if you use an ampersand. It must have been almost as hard work to write up that ampersands don't work as it would have been to fix it so that they do!

One of the missing features from Google maps is a scale. Whilst not impossible to provide, there is one very good reason why this is not provided - Google maps are not drawn to scale!

This Slashdot comment titled Google Maps are awfully distorted anyway explains that

Google Maps uses a fixed longitude/latitude distance ratio of ~0.772, while the true ratio depends on latitude (the ratio should be cos(latitude)). So Google Map is optimized for 39.5 of latitude (N or S), and the maps are increasingly distorted as you go toward the poles or the equator.

The example given shows some streets in Anchorage which are really at right angles, but which show up as a diamond mesh due to the stretching. (Ignore the follow up comments that claim the original post is wrong - they are pointing out north south aligned grids, where of course the right angles are maintained by the stretching anyway). If you want a further example, switch to satellite mode, and observe the round structure to the north west of the runway - which due to the stretching appears as an ellipse shape.

The UK has probably the best national mapping service in the world, in the form of the Ordnance Survey. Their mapping data is used for almost all maps produced in the UK, and UK locations are normally specified using a National Grid Reference - which overlays a grid based on the metric system over the UK.

Google maps is different, even in its UK incarnation - its coordinate system is the universal latitude and longitude, which applies worldwide. The widespread use of GPS has also pushed latitude and longitude to the fore as an everyday system.

Thus there is an increasing need to convert from NGR data to lat/long data, and a few resources which can help are:

• detailed mathematical explanation from Ordnance Survey
• Wikipedia entry

There is ready written code available to do the conversion in

• perl
  
• javascript
• java
  

UK postal addresses also have postcodes, which might similarly be converted to latitude / logitude locations. Resources to help with that are:

• UK Postcodes