[postgis-users] PgRouting in PostGIS

[Stephen Woodbridge]

Nandorov wrote:
> can i block some segments? for example cad gives the posibility to put a max
> resistance value, let's say it's 100. So if the resistance of your segment
> is 100 that segment is blocked and you cannot go thorught this way. if this
> possible with pgrouting?

Yes you can put a high cost on a segment and then it will search for a 
lower cost alternative soultion. In routing you can also have a reverse 
cost that is the cost to traverse the segment from end to start as 
opposed to the cost which is for traversing from start to end. You can 
also just have a single cost that is good for either directions. We use 
high costs to prevent routing the wrong way down one way streets.

Routing solutions from a single best path. There exist different network 
analysis algorithms for doing things like water flow analysis and things 
like that.

-Steve W

> thanks!
> 
> 
> Stephen Woodbridge wrote:
>> Nandorov wrote:
>>> hi,
>>> i've tried pgrouting algorithms and works pretty well. However, i dont
>>> know
>>> exactly the way they applied "the resistance" of a way (represented by a
>>> multilinestring). has someone worked  with pgrouting before? and know if
>>> i
>>> can modify their algorithms to adapt them to my requirements? 
>>>
>>> thanks
>> "the resistance" is applied as a "cost" to traverse the segment. All 
>> cost must be positive. You can use length of the segment as cost for 
>> shortest distance. or you can compute and assign a cost value based on 
>> other attributes.
>>
>> -Steve
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>