RE: Example: Real-time feed of satellite photos

 Gregg Vanderheijden wrote: 

I don't think this one  [satellite photos] actually is a sensory experience.
It is the presentation of specific information.   The "big blue marble"
picture of the earth may be-but not these.   They just fall in the category
of hard to describe in a reasonable number of words.   (someone want to poke
their head up into live fire and suggest what 'reasonable number of words"
would be?)   Hence the problem.

 

This also doesn't deal with the issue of aggregated content in general. 

 

But we need to figure out a way to describe this or people could claim that
other images are just sensory experiences too.   It is  a slippery slope 

 

I agree this isn't a sensory experience, I just felt that for purposes of
providing a text description, they fell in the same category. At the moment,
we have only allowed exceptions for art ("when the sole purpose of the
non-text content is to create a specific sensory experience"), not for other
types of non-text content that is hard to describe into words. I think this
is too narrow a viewpoint. 

 
Even without the problems of realtime imaging and aggregate content,
satellite images are hard to describe. Most descriptions of a satellite
image I can think of will not be a real text equivalent, in the meaning that
they convey the same information as the original. I think we need to
reformulate this guideline.
 
What we seem to want to say is this:
 
<suggestion>
For non-text content, provide text alternatives. Whenever possible the text
alternative should be equivalent to the non-text content, meaning it serves
the same function or conveys the same information as the non-text content.
If a text equivalent is not possible due to the nature of the non-text
content (for example: music and visual art), provide a text label or a
description.
</suggestion>
 
Is this too slippery a definition? Personally, I think many people will
disagree about the function of certain images so the original definition was
slippery anyway (I know several developers who argue that most illustrations
have no real function and deserve null alt text). What constitutes a good
text alternative will be addressed in the gateway techniques so maybe this
suggested definition can suffice...
 
Yvette Hoitink
Heritas, Enschede, The Netherlands
E-mail: y.p.hoitink@heritas.nl
WWW: http://www.heritas.nl <http://www.heritas.nll>