source: trunk/npemap.org.uk/static/FAQ.html @ 19

Last change on this file since 19 was 19, checked in by David Sheldon, 14 years ago

Correction to entry about Scotalnd and NI

File size: 4.7 KB
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1<html>
2<head>
3<title>Free Postcodes!!!</title>
4</head>
5
6<body>
7
8<h2>Free the postcode lite</h2>
9
10
11<h3>What is it?</h3>
12
13<p>There are a lot of uses on websites for being able to tell where
14people are from their postcode. For example "Where is my nearest
15B&amp;Q?". Unfortunately this data is expensive to licence (a few
16thousand pounds/year for a website I believe). <a
17href="http://www.freethepostcode.org">Free the postcode</a> are doing a
18very good job, but it is hard to contribute to their database as you
19need a GPS so they have few postcodes.</p>
20
21<p>The idea is to collect postcode data by getting users to locate
22themselves on a map of the country. They need only give the first part
23of their postcode, and if we can collect locations for all of these
24parts then we can create a database that is 'good enough' for a lot of
25web purposes.
26</p>
27
28<h3>What licence will the data have?</h3>
29
30<p>It will be public domain. Users will have to place their data in the
31public domain. </p>
32
33
34<h3>What maps will you use?</h3>
35
36<p>We have scans of out of copyright OS maps of the whole country.</p>
37
38<h3>Isn't orthowotsiting an old map hard?</h3>
39
40<p>Luckily we're going to work in the OSGB coordinate system that
41matches up with the lines on the map, this means we don't have to
42distort the maps too much. We also are not overly fussy about the
43accuracy, so this step can be done quickly.</p>
44
45<h3>Why don't you use maps created from <a
46href="http://www.openstreetmap.org">Openstreetmap</a> data?</h3>
47
48<p>Because they are licensed under Creative Commons Share-alike
49licences, so we wouldn't be able to make our data public domain.</p>
50
51<p>There are people who believe that locating a point on a map creates a
52derived work, and hence requires a licence. I don't want to be the first
53to prove them wrong in a court as that will be pricy.</p>
54
55<h3>Will this data be imported back into Free the Postcode?</h3>
56
57<p>It might be, that will depend on someone working out how to store
58partial postcode data in Free the Postcode.</p>
59
60<h3>If you are using scans of old maps, how accurate will the locations
61be?</h3>
62
63<p>Some of the scans are out by a degree or two but they are pretty
64good. We hope to be able to get better than 100yds accuracy out of it in
65the end. This is more than good enough to locate a reagion as large as
66the first half of a postcode. </p>
67
68<h3>My house isn't on a 1950s map</h3>
69
70<p>Find some local landmarks, guess where your house is. This is
71accurate enough for our purposes. </p>
72
73<h3>I know exactly where I am, and what my postcode is</h3>
74
75<p>If you have a GPS, enter your data into <a
76href="http://www.freethepostcode.org">Free the Postcode</a> and make the
77world a better place.</p>
78
79
80<h3>Why doesn't it work yet?</h3>
81
82<p>We're still thinking about how this will work, and processing the
83maps so we can use them on the web.</p>
84
85<h3>So, how will I work it?</h3>
86
87<p>Find your location on our map, click where your postcode is, enter
88the postcode, agreeing to release your data.</p>
89
90<h3>psst, I have a copy of the codepoint database wanna look?</h3>
91
92<p>No thanks, we want free data so we don't have to keep paying the nice
93codepoint people. </p>
94
95<h3>Won't you drive codepoint out of business?</h3>
96
97<p>We don't think so, there are a lot of places where this level of
98accuracy just isn't enough. Those people will still have to pay until
99<a href="http://www.freethepostcode.org">Free the Postcode</a> improves
100its coverage.</p>
101
102<h3>The map doesn't join up.</h3>
103
104<p>Yeah, it isn't perfect, the OS didn't publish a single map of the whole
105country so you have to scan then stick together data from several maps. I don't
106really know how to correct it perfectly. It would be really cool if someone
107could write software to detect the gridlines and automatically cut the images
108up on the lines and make them square.</p>
109
110<h3>The wonkiness is so annoying it drives me mad, and I have experience of orthrectifying maps. Please let me straighten your maps.</h3>
111
112<p>Cool. Contact us that would be great.</p>
113
114<h3>Why didn't you use proj/gdal?</h3>
115
116<p>Because I don't know how to work them. Feel like improving how this works, let me know.</p>
117
118<h3>Why don't you have good mapping data of Scotland and Northern Ireland?</h3>
119
120<p>I don't think they were part of the new popular edition at 1inch to the mile. If you have free higher res images of either of these places (we only have quarter inch to the mile) then we might be interested in them.</p>
121
122<h3>Who did the work?</h3>
123
124
125<p>
126<ul><li>Richard Fairhurst acquired and scanned the maps, </li>
127<li>Dominic Hargreaves and David Sheldon straightened and tiled the maps,</li>
128<li>Matthew Westcott, David Sheldon, Dominic Hargreaves and Nick Burch worked on the user interface,</li>
129<ul>
130</body>
131</html>
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