Lucas,
I am not quite sure what you mean by 'in hierarchical terms'. The axial line
is well defined and derived from the built boundary taking account of the
geometry of that full 2d shape. In this it is different to road centre
lines, named streets or any other derivations of these where there seems to
be no definition published, nor a formal derivation from the geometry of the
space itself... or have I missed one? Continuity lines based on axial maps
seem to me to be equally well founded, but if derived from road centrelines
you still have a problem of the foundation being poorly defined in its
relation to the geometry of the open space you are representing. This may
all be somewhat pedantic and I would guess has little effect on results of
the kind that Bin is showing.
Alan
>
> On 30/05/07, Alan Penn <[log in to unmask]> wrote:
> > Agreed - an argument for a (comparatively) well defined concept like the
> > axial line perhaps? :-)
>
> In hierarchical terms axial lines are ill defined. Some streets are
> fragmented into several axial lines while others are not. Therefore
> axial maps throw streets in both directions in the rank-plot, either
> fragmenting or aggregating. Without mentioning that many axial lines
> are projections of curves in the 3D space. Therefore, the
> fragmentation of curves in 2D is not justifiable.
>
> Continuity maps have a unified strategy: aggregate until a threshold,
> therefore all "streets" are moved to the upper rank. In this sense
> they are better defined.
>
> The question is the threshold. Can we aggregate radial streets and
> create circles? So on...
>
> Regards,
> Lucas
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