source: trunk/npemap.org.uk/static/FAQ.html @ 210

Last change on this file since 210 was 210, checked in by Dominic Hargreaves, 14 years ago

Pedantry

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1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
2<html>
3<head>
4<title>FAQ | New Popular Edition Maps</title>
5</head>
6
7<body>
8
9<h2>Free the postcode lite</h2>
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>Where's the data, then?</h3>
37
38<p>We are still in the early stages of collecting data. We want to make
39sure that the data is in an appropriate format, that we have some quality
40control, and that we release the data in an appropriate format, before
41doing so.
42</p>
43
44<p>
45If you desperately want the data sooner, <a href="reportBug.html">get
46in touch</a>.
47</p>
48
49<h3>What maps are you using?</h3>
50
51<p>We have scans of out of copyright OS maps of England and Wales.
52You can <a href="scotlandAndNI.html">register interest in future
53projects involving Scotland and Northern Ireland</a>.</p>
54
55<h3>So can I do what I like with your scans/tiles?</h3>
56
57<p>
58No. The scans and tiles have been placed under a
59<a href="tileLicence.html">licence</a>; they are not in the public
60domain.
61</p>
62
63<h3>Okay; I can use the tiles for some things; can I download the complete set?</h3>
64
65<p>
66Not yet. We need to make sure we've uncovered all the obvious flaws with
67the current tiles (eg human error in cropping and numbering the tiles)
68and have worked out an efficient distribution format.
69<a href="reportBug.html">Let us know</a> if you want to
70use the tiles; please don't try and crawl our tileserver to obtain the entire
71set.
72</p>
73
74<h3>Isn't orthowotsiting an old map hard?</h3>
75
76<p>Luckily we're going to work in the OSGB coordinate system that
77matches up with the grid lines on the map; this means we don't have to
78distort the maps too much. We also are not overly fussy about the
79accuracy, so this step can be done quickly.</p>
80
81<h3>Why don't you use maps created from <a
82href="http://www.openstreetmap.org">OpenStreetMap</a> data?</h3>
83
84<p>Because they are licensed under Creative Commons Share-alike
85licences, so we wouldn't be able to make our data public domain.</p>
86
87<p>There are people who believe that locating a point on a map creates a
88derived work, and hence requires a licence. We don't want to be the first
89to prove them wrong in a court, as that will be pricy.</p>
90
91<p>Also, the OpenStreetMap maps are not yet complete enough to achieve our
92goal of country-wide coverage.</p>
93
94<h3>Will this data be imported back into Free the Postcode?</h3>
95
96<p>It might be, that will depend on someone working out how to store
97partial postcode data in Free the Postcode. We are importing Free the
98Postcode data into our database.</p>
99
100<h3>If you are using scans of old maps, how accurate will the locations
101be?</h3>
102
103<p>Some of the scans are out by a degree or two but they are fairly
104good. We hope to be able to get better than 100 metres accuracy out of it in
105the end. This is more than good enough to locate a region as large as
106the first half of a postcode, and hopefully as much as the 'partial'
107postcodes described in the answer to 'What is it?' above.</p>
108
109<h3>My house isn't on a 1950s map</h3>
110
111<p>Find some local landmarks and guess where your house is. This is
112accurate enough for our purposes.</p>
113
114<h3>I know exactly where I am, and what my postcode is</h3>
115
116<p>If you have a GPS, enter your data into <a
117href="http://www.freethepostcode.org">Free the Postcode</a> and make the
118world a better place.</p>
119
120<h3>So, how do I use it?</h3>
121
122<p>Find your location on our map, click where your postcode is, enter
123the postcode, agreeing to release your data.</p>
124
125<h3>Psst, I have a copy of the codepoint database. Wanna look?</h3>
126
127<p>No thanks, we want free data so we don't have to keep paying the nice
128codepoint people. </p>
129
130<h3>Won't you drive codepoint out of business?</h3>
131
132<p>We don't think so. There are a lot of places where this level of
133accuracy just isn't enough. Those people will still have to pay until
134<a href="http://www.freethepostcode.org">Free the Postcode</a> improves
135its coverage.</p>
136
137<h3>The map doesn't join up.</h3>
138
139<p>Yes, it isn't perfect. The OS didn't publish a single map of the whole
140country, so you have to scan then stick together data from several maps.
141We don't really know how to correct it perfectly. It would be really cool
142if someone could write software to detect the gridlines and automatically
143cut the images up on the lines and make them square.</p> 
144
145<h3>The wonkiness is so annoying it drives me mad, and I have experience of orthrectifying maps. Please let me straighten your maps.</h3>
146
147<p>Cool. Contact us, that would be great.</p>
148
149<h3>Why didn't you use proj/gdal?</h3>
150
151<p>Because we don't know how to work them. If you feel like improving how this
152works, let us know.</p>
153
154<h3>Why don't you have good mapping data of Scotland and Northern Ireland?</h3>
155
156<p>I don't think they were part of the New Popular Edition at 1 inch to the
157mile. If you have free higher resolution images of either of these places
158(we only have quarter inch to the mile) then we might be interested in them.</p>
159
160<h3>Who did the work?</h3>
161
162<ul>
163<li>Richard Fairhurst acquired and scanned the maps,</li>
164<li>Dominic Hargreaves and David Sheldon straightened and tiled the maps,</li>
165<li>Matthew Westcott, David Sheldon, Dominic Hargreaves and Nick Burch worked on the user interface and backend software.</li>
166</ul>
167</body>
168</html>
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