Dear Bin,

You and I are active participants of this list. I publicised several
times my work here as "continuity lines" and the generalisation
process based on angles. Even though you wrote your paper for another
audience, It would be more elegant to cite axial lines as a
generalisation process (as named streets) and continuity lines, taking
in account the fact that my work offer several details of how can we
aggregate using angles.

Sorry if I sounded as blaming you for "intentional" ignorance. This is
not the case. My intention was to point that all similar sources
should be cited to offer a more vivid discussion about the subject,
and improve the quality of your paper, as I have done in mine (pages 2
and 3):
http://eprints.ucl.ac.uk/archive/00002694/

Your are a multidisciplinar researcher, If you do not do an effort to
cite your collegues from other fields in your work, how do you expect
to get cited as we can always use an alternative citation within our
field?

Best Regards,
Lucas Figueiredo

On 31/05/07, Bin Jiang <[log in to unmask]> wrote:
> Dear Lucas,
>
> Be careful when put such a blame on someone. We did communicate with
> Robert on the implementation of algorithm, so the reference is cited
> there. You could also verify with him. I must say  that if there is any
> "ignorance", this is totally unintended. We have no intention whatsoever
> to ignore your contribution, if any. As for the degrees, we communicated
> with another researcher, but failed to get an answer. We experimented it
> with my Gävle data with several ring roads there. The 70 degree is
> completely based on our experiments independently.
>
> Cheers.
>
> Bin
> Figueiredo wrote:
> > Dear Bin,
> >
> > 1) I read your paper and I found very rude from you using my algorithm
> > to aggregate lines without citing my work. Linear Strokes (look for
> > Robert Thomson) are a wider concept that searches generalisation (as
> > in Jiang B. and Claramunt C. (2004), A structural approach to model
> > generalisation of an urban street network). It can be applied not only
> > to streets, but also to river networks, for instance.
> >
> > Robert's suggestion for replacing axial lines for linear strokes
> > (Thomson, 2003, bending the axial line) assumes a classic street
> > network based on the node-junction representation. The only know real
> > implementation of this approach is Porta et al (2006), which has a
> > clever and efficient algorithm that negotiates the best continuity.
> >
> > Aggregating lines straight away from street segments (either axial
> > lines or road centre lines) using an "Angle of Deflection" was
> > proposed by me:
> >
> > "The technical procedure to aggregate axial lines is based on the
> > "aggregation angle" or "angle of continuity", which is the angle
> > between the linear continuation of an axial line and the "real"
> > continuation provided by another axial line " (Figueiredo and Amorim,
> > 2004, p5)
> >
> > "The implementation of the aggregation process is based on the angle
> > between the lin-
> > ear continuation of an axial line and the \real" continuation provided
> > by another axial
> > line closer to one of its extremities. This angle of intersection is
> > called "angle of continu-
> > ity" " (Figueiredo and Amorim, 2005, p164)
> >
> > "The software was designed to read any existent axial map (...), but
> > it can also be adapted to create continuity maps from GIS databases
> > (Figueiredo and Amorim, 2005, p166)"
> >
> > Instead of using Porta's algorithm, which is better for road centre
> > lines, you apparently adopted my algorithm with a very wider angle (70
> > degrees). It happens that you may have created crazy curves when
> > better continuities were availalble. The relevance of the aggregation
> > procedure for your paper is crucial, as the "power laws" are created
> > by the generalisation process.
> >
> > I would say that a proper citation would not reduce the merit of your
> > contribution, could would  improved it. Note how one can cite properly
> > his colleagues (Pages 2 and 3):
> > http://eprints.ucl.ac.uk/archive/00002694/
> >
> > 2) Your power-laws are curves. There is few samples in your plots
> > where one could choose a cut-off point and find a tail that resembles
> > a straight line.
> >
> > 3) Instead of using your definition of n-neighbour clustering
> > coefficient, which is more appropriate for street networks, you used
> > the standard one. Street networks are grids, therefore we should look
> > a cycles with 3 steps (squares), not only 2 (triangles).
> > http://eprints.ucl.ac.uk/archive/00002694/
> >
> > Best Regards,
> > Lucas
> >
> > On 31/05/07, Bin Jiang <[log in to unmask]> wrote:
> >> Thanks all for the interesting discussion. Herewith my feedback:
> >>
> >> The log-log lines are not very straight, and in some case seem pretty
> >> curved. However the pattern (80/20 partition around the average m) we
> >> illustrated seems universal. With this pattern we do believe power-law
> >> there.
> >> > but this is curved throughout the length - very clearly so - I
> >> suspect a
> >> > simple power function which would still be interesting...
> >> >
> >> >
> >> >> One of the problems I had in the Physica A paper was that we do
> >> not know
> >> >> what a street is. There are several representations out there, but
> >> there
> >> >> is no uniquely accepted concept?
> >> >>
> >> >
> >> > Agreed - an argument for a (comparatively) well defined concept
> >> like the
> >> > axial line perhaps? :-)
> >> >
> >> Well, I cannot agree with the point. Through the experiments, we see the
> >> concept of streets based on perceptual grouping is pretty clearly
> >> defined, much better than axial lines. People may argue that the
> >> criteria of good continuity is a bit vague. In fact, we tried different
> >> threshold angles (actually a series from 20 to 90 degrees) for merging
> >> (or grouping) street segments to form individual streets, and found no
> >> big change in the illustrated pattern. One of my students Chengke Liu
> >> has testified three models: axial, stroke, named streets, and found the
> >> latter two are the best.
> >>
> >> Cheers.
> >>
> >> Bin
> >>
> >> --
> >> ------------------------------------------------
> >> Bin Jiang
> >> Department of Land Surveying and Geo-informatics
> >> The Hong Kong Polytechnic University
> >> Hung Hom, Kowloon, Hong Kong.
> >> Tel: (852) 2766 4335, Fax: (852) 2330 2994
> >> Email: [log in to unmask]
> >> ------------------------------------------------
> >>
> >
> >
>
>
> --
> ------------------------------------------------
> Bin Jiang
> Department of Land Surveying and Geo-informatics
> The Hong Kong Polytechnic University
> Hung Hom, Kowloon, Hong Kong.
> Tel: (852) 2766 4335, Fax: (852) 2330 2994
> Email: [log in to unmask]
> ------------------------------------------------
>


-- 
Lucas Figueiredo
http://www.flickr.com/photos/lucasfigueiredo/

Mindwalk
http://www.mindwalk.com.br