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Maps that are accessible

From: Charles McCathieNevile <charles@sidar.org>
Date: Sun, 6 Jun 2004 13:00:13 +0200
Message-Id: <AF52EC8C-B7A8-11D8-8FB6-000A958826AA@sidar.org>
To: "'w3c-wai-ig@w3.org' Group" <w3c-wai-ig@w3.org>

Jesper wrote, 50-odd messages ago, about how to make maps that are 

(Please stick to the topic, or change the subject label)

One of the interesting questions in making maps accessible is what kind 
of content is useful. Obviously for a blind person it is no good to 
have a picture that can't be interepreted.

Many mapping systems actually store information, not just pictures. 
They use this to generate a picture, but can also tell you useful 
things like how far to go, where to turn, etc. For example, travel 
1.4km, taking the third turn on your left, which is One street. Go 
800m, taking the second turn on the right, which is What st. Follow for 
200m to a 6-way interrsection....

It essentially depends on the system used to store the information, and 
how it is presented. Given the right data model you can use scripts and 
PDF, or HTML embedded in an ActiveX control, or whatever you like, 
since a decent programmer and a bit of talking to users can give you 
some appropriate output forms for the information.

Further, one of the topics was about zooming. There are simple ways to 
do this with images in HTML - you can readily divide a square into 9 
parts (because it's easy to imagine) and then make each area link to a 
view zoomed by 50%. It's easy to make redundant text links for all 

Handling zooming is often done with Flash in commercial sites, or with 
SVG by real geographers, at the moment, and some standard and open 
format richer than HTML is probably in fact appropriate. For everyone 
who has a reasonably modern and capable browser - you should still be 
able to generate pretty moronic HTML that is useful to people with a 
first-generation i-mode phone.

One of the benefits of a format like SVG is that you can carry the 
information inside the document, supporting powerful, accessible 
processing on either client or server side.



Charles McCathieNevile                          Fundación Sidar
charles@sidar.org                                http://www.sidar.org
Received on Sunday, 6 June 2004 07:00:54 UTC

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