Sunday 25 March 2012

More GB postcode goodness

I have loaded the CodePoint Open data into a database some time ago. It was released as part of the OpenData from Ordnance Survey, though it is Royal Mail data originally. As part of the bundle it provides the northing and easting of the centroid of GB postcodes. I converted these OS grid references into longitude and latitude using gdaltransform and loaded them into a database. I use this to make postcode overlay tiles for use in editors or on maps.

In a recent discussion with Dan Avis I realised that I hadn't done as originally intended and created a postcode finder. When I have the data to hand it seems daft not to go the final mile, so I have. You can see it here. It uses the lovely Leaflet library to display the map and I use a small trick to only show the postcodes at high enough zoom level. Whenever the map is redisplayed I check the zoom level and hide or show the postcode tiles as required.

I have deliberately separated the attribution from the map because the text was too long for the map size I liked. In a while I will have to see what attribution changes are needed, if any, to the various maps I have created as the licence changes.

Monday 19 March 2012

Red shift

Red shift* is a phenomenon than makes things change their colour. It is usually applied to stars.

There are groups of people shifting the red from the OSMI licence change view by remapping the work of people who have declined the new licence or whom we cannot contact any more.
These shifters of red are stars, everyone of them and I thank them, along with the folks who built the tools to show what needs to be shifted. Bravo.

* red shift is caused as space that makes up the fabric of the universe is stretched because the universe is expanding. This stretches the light coming from distant stars changing its wavelength towards the red end of the spectrum, hence 'red shift'.