Intrestingly enough you can have two seperate networks in webmap.
Traditional axman had the concept of unlinks - if you had a train line you
would have to unlink it from all the lines which cross it. tediious but
possible.
Webmap superceeds this with a new concept known as a superlink. A super
link is the opposit of a 'unlink'. So in webmap if you have two floors you
could link them together at the lifts/stairs with superlinks.
Another use of superlinks I indended was the study of the influence of the
underground and the bus network. You would superlink all the streets which
are linked to the same tube line together. You can include a weight to
represent 'distance' or 'utility' or or what ever you want.
Any number of networks can be overlayed to form what Mathemations refer to
as a 'hypergraph'.
see http://bat.vr.ucl.ac.uk/webmap/
webmap is partly open source - is anyone but me intreasted in open source
software ?
sheep
> I am afraid I don't have any advice about how to handle this problem in
> Axman but it is handled consistently in my paper "Distance in Space
> Syntax" where I show how you can deal with two different networks such
> as railway lines that only intersect with streets at infrequent points
> but that this requires a different formalism from traditional space
> syntax. Where the railway crosses under or over a street, it does not
> normally intersect it. Unfortunately there is no public domain software
> to compute this available as yet.
>
> But see the paper at
> http://www.casa.ucl.ac.uk/working_papers/paper80.pdf
>
> and Figure 6 et seq in that papers show pictures of where the loop
> railway goes under streets in central Melbourne. I think that these
> kinds of problems cannot be handled consistently in traditional space
> syntax because it requires different networks to be handled and this
> means that we need to move to thinking of streets and intersections as
> raw data where the Euclidean coincidence of one street with another does
> not automatically imply a junction.
>
> Mike
>
>
> At 10:26 05/05/04 +0200, Bernhard Snizek wrote:
>>Dear Victor, Sanjay,
>>
>> what about using field isovists or visual graph analysis in a grid ?
>>By defining in a boolean grid you could control where potential
>>pedestrians could or cannot reside....
>>
>>Maybe one has to extend axial analysis when it comes to open spaces in
>> the city like squares, parks etc to a hybrid form of isovist/axial
>> analysis.
>>
>>best regards
>>
>> Bernhard
>>
>>On 5/5-2004, at 10.16, Sanjay Rana wrote:
>>
>>>victor,
>>>
>>>quite an interesting question. i suppose there must already exist a
>>> formal
>>>methodology to deal with this situation. I am personally of the
>>> opinion that urban transport networks (e.g. roads, railways) already
>>> contain some
>>>degree of integration measures by virtue of their properties such as
>>> speed,
>>>capacity, safety, diretion (one-ways etc.), attraction (shops,
>>> garages, scenic routes etc.). In my field of research (terrain
>>> analysis), I deal with this situation in two ways:
>>>
>>>I assign a certain amount of weights to features (e.g. if you want to
>>> go
>>>faster then you would take the motorway even if you could potentially
>>> take
>>>a "topological" short cut via a network of small roads. Therefore,
>>> what I
>>>am essentially suggesting is as follows:
>>>Could you assign certain weights to the unused links (in fact all the
>>> links) but still have them in your analysis for "topological
>>>completeness"?
>>>
>>>2. Secondly, please note, that this will also take you the edges of
>>> the transport planning discipline (an active mailing list at
>>>http://www.its.leeds.ac.uk/utsg/). In transport planning, such
>>>"unconnected
>>>networks" are sometimes assigned (linked) to a connected part of the
>>> network (just pick any nearest road to the isolated path) which yields
>>> a
>>>completely connected network. But if the paths are blocked then thats
>>> a different issue.
>>>
>>>i hope this brain spill helps !
>>>
>>>sanjay.
>>>
>>Bernhard Snizek
>>landscape architect MDL MSc
>>
>>metascapes
>>Ravnsborggade 2,2
>>DK2200 Copenhagen N
>>Denmark
>>
>>http://www.metascapes.dk
>>tlf: ++45 23710046
>
> _________________________________________________
> Michael Batty, Director, CASA, University College London,
> 1-19 Torrington Place London WC1E 6BT, UK
> [t] 44 (0) 207 679 1781, [f] 44 (0) 207 813 2843
>
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> http://www.casa.ucl.ac.uk/people/MikesPage.htm
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