On Tue, 13 Jun 2006 08:56:52 +0100, Rui Carvalho <[log in to unmask]> wrote:
>
>What are the SS graduate students being taught these days? That the SLoS
>is a book on spatial analysis? That SS is about studying spatial networks?
Urban Traffic Dynamics: A Scale-Free Network Perspective
http://lanl.arxiv.org/abs/physics/0606086
>
>Does anyone at space syntax know what these things are??? Have any of the
>graduate students ever cared to do a search for ‘spatial analysis’ in
>google or amazon???
http://tinyurl.com/qrrwy
Rui
>
>Rui
>
>
>
>>Oh, and I thought it was you that asked us not to ignore this
>request... :-)
>>
>>Alan
>>
>>
>>> Dear Alan,
>>>
>>> Could you be as kind as to send us a published (journal) reference which
>>> points this out.
>>>
>>> You see, we've all read enough emails by now.
>>>
>>> Thank you
>>>
>>> > -----Original Message-----
>>> > From: [log in to unmask] [mailto:[log in to unmask]]
>On
>>> > Behalf Of Alan Penn
>>> > Sent: 03 March 2006 14:53
>>> > To: [log in to unmask]
>>> > Subject: Re: [SPACESYNTAX] NOT ignore please
>>> >
>>> > Its funny isn't it? I wonder why people have trouble with this one.
>>> >
>>> > The RA equation puts mean depth onto a 1-0 scale between the deepest
>and
>>> the
>>> > shallowest you could possibly have given that number of nodes in the
>>> graph.
>>> > This is a normalisation.
>>> >
>>> > The RRA equation then relativisies this as compared to the mean depth
>of
>>> a
>>> > diamond shaped structure with the given number of nodes. This is an
>>> > empirical relativisation ie. not particularly 'theory driven' in that
>it
>>> > works statistically in removing the effects of number of nodes in
>urban
>>> > axial graphs from the average mean depth in a system. There are many
>>> other
>>> > ways that this could be done, and since there is no pre-existing
>>> theoretical
>>> > assumption built into this process nothing is lost by ding it a
>>> different
>>> > way. However, it does allow you to compare some properties of graphs
>>> between
>>> > maps of different sizes on a more or less comparable basis. Something
>>> you
>>> > certainly cannot do for the unrelativised RA values.
>>> >
>>> > Alan
>>> >
>>> >
>>> > >
>>> > > On 03/03/06, Bin Jiang <[log in to unmask]> wrote:
>>> > > > Usually we compare space syntax measures within a same system, not
>>> > > > across different systems. This is my perception. Am I wrong?
>>> > >
>>> > > Well, if you use local integration for a single axial map you *are*
>>> > > comparing different systems because the number of nodes involved to
>>> > > calculate this measure vary for each node. It is the same if you
>>> > > compare global integration between different maps.
>>> > >
>>> > > Therefore, if you do not agree that RRA / Diamond Shapes provides
>some
>>> > > help... forget the whole thing about local integration... just does
>>> > > not work.
>>> > >
>>> > > For me it is quite OK.
>>> > >
>>> > > > I am not convinced by the popular saying that the local
>integration
>>> is
>>> a
>>> > > > good indicator of pedestrian or vehicle flows. Recently I happened
>>> to
>>> > > > get some vehicle observation datasets with pressure-sensed
>>> techniques
>>> > > > (so must be very precise observation). I compared the datasets
>with
>>> > > > local integration, and did not end up with a good correlation (R
>>> square
>>> > > > value about 0.5).
>>> > >
>>> > > I have got the same in this paper:
>>> > > "Continuity lines: aggregating axial lines to predict vehicular
>>> > > movement patterns"
>>> > > http://www.mindwalk.com.br/papers/
>>> > >
>>> > > That is a problem. I produced a continuity map that reveals clearly
>>> > > the main street system of my city (Recife, Brazil). But ...
>correlate
>>> > > abstract graph properties with real movement is another issue. There
>>> > > are many other factors, such as attractors, street width, etc.
>>> > >
>>> > > Therefore, this is just a matter what is the number you accept as a
>>> > > good proof that the urban grid itself (ignoring the other factors)
>can
>>> > > organise movement patterns.
>>> > >
>>> > > Regards!
>>> > > Lucas Figueiredo
>>> > >
>>> > > CASA - Centre for Advanced Spatial Analysis
>>> > > University College London
>>> > > 1-19 Torrington Place
>>> > > London WC1E 7HB England
>>> > > E-mail: [log in to unmask]
>>========================================================================
>========================================================================
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