HI all,
interesting debate. In our paper (Tomko, M., Winter, S., & Claramunt, C.
(to appear). Experiential Hierarchies of Streets. Computers, Environment
and Urban Systems.) we used named streets as we are interested in
reconstructing the experiential hierarchies of streets, allowing
strangers to assume what streets their communication partner may know, and
consecutively refer to them in destination descriptions.
Re continuity lines, I tried to use them in conjunction with the
"straight"
direction concept (e.g., Alexander Klippel, Heike Tappe, Lars Kulik, Paul
U. Lee (2005).Wayfinding Choremes - A Language for Modeling Conceptual
Route Knowledge. In Journal of Visual Languages and Computing, 16 (4), pp.
311–329.) and it works quite nicely. This is one of the few cognitively
motivated sources of angles I know of usable in this context. The
correlation of continuity lines with named streets was high, and allowed
hierarchically higher chunking of streets changing e.g., street type
(arbitrary choice, such as victoria street changing into Victoria parade
in Melbourne... it is the "same" street...)
I was wondering, Bin, how/why you selected only 1% of the most central
streets as the backbone... I still have to reda the paper, I guess.
Martin
> 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]
> ------------------------------------------------
>
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