[postgis-users] Open Source GIS System

[Stephen Woodbridge]

This is interesting. Why do you have to reprocess the whole network? I 
would think that you could just mark a segment as be temporarily blocked 
and then structure your Dijkstra algorithm to look for the blocked flag 
and terminate progress at that point.

Of course this assumes that the code is designed to handle this in the 
first place. The blocks do not even have to be in the network data, 
although that is probably the most efficient way to organize it, it 
presents problems if you have multiple thread solving different problems 
using the same base network.

-Steve

Milo van der Linden wrote:
>   >From my experience with a firebrigades application in the Netherlands 
> where we calculate drive time spiders, I know that every time you 
> generate a road block or open a road, the entire network has to be 
> pre-processed. In the case we went through, this ment recalculating a 
> network of 200000 streetsegments per customer and re-calculation took an 
> average of 20 seconds. So it is technically possible, just make sure you 
> make it a well structured background process.
> 
> Jason Birch schreef:
>> Have you seen the dynamic routing that Christopher Schmidt has done 
>> with OpenLayers?
>>  
>> http://crschmidt.net/blog/archives/268/openlayers-routing-with-a-little-help-from-my-friends/ 
>>
>>  
>> It's pretty cool.  Much of the routing work could be done for you by 
>> using this code (assuming that Chris is sharing).  I think that in 
>> either case the network has to be pre-calculated though, so on-the-fly 
>> addition of road blocks and the like may not be technically possible.
>>  
>> Jason
>>
>> *From:* Matthew Pulis
>> *Subject:* [postgis-users] Open Source GIS System
>> I am preparing to build up a GIS system as part of my University 
>> Masters Thesis. My final aim is to build a system where the user 
>> inputs (or via GPS) 
>> inputs the location where he is and the location where he want to go and gets the route planned. My main concern will be that the driver can decide which route to take, if the shortest 
>> distance, least time consuming or else least fuel consumption. Also 
>> the route planned has to be aware of certain problems that the network 
>> can find, for example road blocks, or some other type of incidents / 
>> accidents.
>>  
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> 
> 
> -- 
> 
> 
> 	
> 
> Milo van der Linden
> skype: milovanderlinden <skype:milovanderlinden?add>
> mlinden at zeelandnet.nl <mailto:mlinden at zeelandnet.nl>
> milovanderlinden at gmail.com <mailto:milovanderlinden at gmail.com>
> milo at 3dsite.nl <mailto:milo at 3dsite.nl>
> http://www.3dsite.nl
> 
> 	  	
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