source: trunk/npemap.org.uk/static/FAQ.html @ 85

Last change on this file since 85 was 85, checked in by Dominic Hargreaves, 14 years ago

Style/grammar improvements.

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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 applications 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). <a
17href="http://www.freethepostcode.org">Free the postcode</a> are doing a
18good job, but it is hard to contribute to their database as you
19need a GPS, so they have few postcodes.</p>
20
21<p>Our goal 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 many
25applications. We are also accepting complete postcodes and 'partial'
26postcodes including the number portion of the second half of the postcode,
27in order to improve our accuracy.
28</p>
29
30<h3>What licence will the data have?</h3>
31
32<p>The data will be will be in the public domain; consequently, users
33submitting data agree to their submission being in the public domain
34when they enter their postcode.</p>
35
36<h3>What maps are you using?</h3>
37
38<p>We have scans of out of copyright OS maps of England and Wales.
39You can <a href="scotlandAndNI.html">register interest in future
40projects involving Scotland and Northern Ireland</a>.</p>
41
42<h3>So can I do what I like with your scans/tiles?</h3>
43
44<p>
45No. The scans and tiles have been placed under a
46<a href="tileLicence.html">licence</a>; they are not in the public
47domain.
48</p>
49
50<h3>Isn't orthowotsiting an old map hard?</h3>
51
52<p>Luckily we're going to work in the OSGB coordinate system that
53matches up with the grid lines on the map; this means we don't have to
54distort the maps too much. We also are not overly fussy about the
55accuracy, so this step can be done quickly.</p>
56
57<h3>Why don't you use maps created from <a
58href="http://www.openstreetmap.org">OpenStreetMap</a> data?</h3>
59
60<p>Because they are licensed under Creative Commons Share-alike
61licences, so we wouldn't be able to make our data public domain.</p>
62
63<p>There are people who believe that locating a point on a map creates a
64derived work, and hence requires a licence. We don't want to be the first
65to prove them wrong in a court, as that will be pricy.</p>
66
67<p>Also, the OpenStreetMap maps are not yet complete enough to achieve our
68goal of country-wide coverage</p>.
69
70<h3>Will this data be imported back into Free the Postcode?</h3>
71
72<p>It might be, that will depend on someone working out how to store
73partial postcode data in Free the Postcode. We are importing Free the
74Postcode data into our database.</p>
75
76<h3>If you are using scans of old maps, how accurate will the locations
77be?</h3>
78
79<p>Some of the scans are out by a degree or two but they are fairly
80good. We hope to be able to get better than 100 metres accuracy out of it in
81the end. This is more than good enough to locate a region as large as
82the first half of a postcode, and hopefully as much as the 'partial'
83postcodes described in the answer to 'What is it?' above.</p>
84
85<h3>My house isn't on a 1950s map</h3>
86
87<p>Find some local landmarks and guess where your house is. This is
88accurate enough for our purposes.</p>
89
90<h3>I know exactly where I am, and what my postcode is</h3>
91
92<p>If you have a GPS, enter your data into <a
93href="http://www.freethepostcode.org">Free the Postcode</a> and make the
94world a better place.</p>
95
96<h3>So, how do I use it?</h3>
97
98<p>Find your location on our map, click where your postcode is, enter
99the postcode, agreeing to release your data.</p>
100
101<h3>Psst, I have a copy of the codepoint database. Wanna look?</h3>
102
103<p>No thanks, we want free data so we don't have to keep paying the nice
104codepoint people. </p>
105
106<h3>Won't you drive codepoint out of business?</h3>
107
108<p>We don't think so. There are a lot of places where this level of
109accuracy just isn't enough. Those people will still have to pay until
110<a href="http://www.freethepostcode.org">Free the Postcode</a> improves
111its coverage.</p>
112
113<h3>The map doesn't join up.</h3>
114
115<p>Yes, it isn't perfect. The OS didn't publish a single map of the whole
116country, so you have to scan then stick together data from several maps.
117We don't really know how to correct it perfectly. It would be really cool
118if someone could write software to detect the gridlines and automatically
119cut the images up on the lines and make them square.</p> 
120
121<h3>The wonkiness is so annoying it drives me mad, and I have experience of orthrectifying maps. Please let me straighten your maps.</h3>
122
123<p>Cool. Contact us, that would be great.</p>
124
125<h3>Why didn't you use proj/gdal?</h3>
126
127<p>Because we don't know how to work them. If you feel like improving how this
128works, let us know.</p>
129
130<h3>Why don't you have good mapping data of Scotland and Northern Ireland?</h3>
131
132<p>I don't think they were part of the New Popular Edition at 1 inch to the
133mile. If you have free higher resolution images of either of these places
134(we only have quarter inch to the mile) then we might be interested in them.</p>
135
136<h3>Who did the work?</h3>
137
138<p>
139<ul>
140<li>Richard Fairhurst acquired and scanned the maps,</li>
141<li>Dominic Hargreaves and David Sheldon straightened and tiled the maps,</li>
142<li>Matthew Westcott, David Sheldon, Dominic Hargreaves and Nick Burch worked on the user interface.</li>
143<ul>
144</body>
145</html>
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