[RouterGeocoder] Poly line features

[Stephen Woodbridge]

Roni,

You can not abandon the polylines, you don't need them loaded in memory 
when solving the graph, but you will need pointers or ids so you can 
later extract the full edge geometry for mapping and for analyzing the 
intersections when you want to generate driving instructions.

Remember data always expands and exceeds the space allocated to store it!

-Steve

Ashraf Hossain wrote:
> For each polyline feature(single part) the starting point and endpoint
> is treated as vertex.
> And a polyline feature(single part) as an edge.
> 
> Then for each polyline we have to keep 2 vertex index.
> Number of vertex * sizeof(long) * Number of feature
> Data structure size :  2 * 4 * 35000000 = 260 MB;
> 
> For Each vertex the number of edge connected (on average 4)
> Number of Edge(on average 3 to 4) * sizeof(long) number of feature +
> Number of vertex * long
> Data structure size :4  * 4 * 35000000 = 520 MB + 260 MB
> If the graph is with single parameter(length)
> Number of vertex(on average 3 to 4) * sizeof(long) number of feature
> Data structure size: 4  * 4 * 35000000 = 520 MB
> 
> So for huge size layer the at best the graph manager need 1.6 GB memory.
> Now a days 64 bit is too much available and then a server with 4 GB is
> not a matter.
> So i think this is not a big deal at all.
> 
> This is an approximtion value. practically the graph server will take
> less than 1.6 GB
> 
> 
> Kind Regards
> Roni
> 
> 
> On Mon, Feb 2, 2009 at 1:07 AM, Stephen Woodbridge
> <woodbri at swoodbridge.com> wrote:
>> Ashraf Hossain wrote:
>>> How many polyline features are in whole north america?
>>> Can anyone send me a approximate value??
>>> Before planning the router and navigation engine I need to know this.
>> For the US and Canada there are in the ball park of 25-30 million segments
>> based on Navteq data. There are a similar number of segments in Tiger
>> althought Tiger does not have all the attributs needed to use it for
>> routing. Western Europe as a similar, slightly higher number of segments in
>> the 30-35 million range. If you plan around these numbers you should be
>> good.
>>
>> -Steve W
>>