Hi Terry,
As others has pointed out, you need routing software for this problem. Our
solutions can do it as either polygon isochrones or as a "thematic
colouring" of the links, which may only go half way down the C-D link (2 min
+ the 3 min on the B-C link), so you get exactly 5 minutes.
Even if your boss is happy with the simple buffer isochrones, you can always
have a trial license so you can show to him, how it can be done.
Kind regards
Uffe Kousgaard
www.routeware.dk
----- Original Message -----
From: "Terry McDonnell" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, September 21, 2005 6:04 PM
Subject: MI-L Too difficult for any of you :-)
Hi List
This is a tricky one. I need to display "isochrones" around bus stops,
i.e. how far someone could walk, from the stop, in 5, 10, 15 mins etc.
OK, it's easy to create a circular buffer zone and display that but
consider the following:
A
/\ C 5mins D
/ \ ____________|___________
4mins / \5mins /
/ \ /
E / \ / 3mins
__________________\B/
\
\
\ 5mins
\
\
\F
The lines represent roads and point B is the bus stop. Now suppose a "5
minutes' walk" radius were drawn around point B. It would likely
encompass point D too. But to get to point D you have to walk along
road B-C, then C-D. But the distance B-C is 3 mins, and C-D is 5 mins =
8 mins in reality.
Point E would easily come within the 5 mins radius, but you have to walk
B-A, then A-E = 9 mins.
Essentially then, is it possible to follow all possible routes from the
origin to give a buffer around the streets?
The streets level is represented by a series of contiguous polylines,
each representing elementary street units (ESU). Pythagoras is out of
the reckoning cos we don't know the angles of street intersections, as
well as the heuristic nature of the program would be horrendous to
follow all branches, etc.
I figure this one is a bit too difficult to do, but I've only been
looking into it all afternoon so far!
Any ideas, experience of this, nifty solutions?
'ppreciate it
Terry McDonnell
---------------------------------------------------------------------
List hosting provided by Directions Magazine | www.directionsmag.com |
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
Message number: 18008
