very large tile index

[Ludovico Bianchini]

Thanks for suggestions, I think I will try to use GRASS or OpenJUMP 
(http://openjump.org/wiki/show/HomePage).

Ludovico Bianchini

----- Original Message ----- 
From: "Frank Warmerdam" <warmerdam at POBOX.COM>
To: <MAPSERVER-USERS at LISTS.UMN.EDU>
Sent: Thursday, October 18, 2007 3:45 PM
Subject: Re: [UMN_MAPSERVER-USERS] very large tile index


> Ludovico Bianchini wrote:
>> Is ogrtindex able to create a "fusion" of many shape files?
>> If it is the same as tile4ms (= it creates an index file which references 
>> many shape files), the problem is not solved: when building the max 
>> extent of the map with, for example, a layer with state, region and city 
>> boundaries, almost all the shape files indexed must be opened and 
>> processed, causing very bad performance.
>> The solution
>> "The operational solution is to create a low  resolution
>> MOSAICED layer all in one file and use MINSCALE/MAXSCALE on the layers to
>> switch between the tileindex layer and the overview layer at appropriate
>> scales"
>> wrote by Frank Warmerdam speaks about an union of many single files 
>> covering small region in a greater file covering a bigger region. The 
>> solution sounds good also for vector data, but I don't know any tool to 
>> create such a bigger shape file containing features, not tiles pointers.
>
> Ludovico,
>
> ogrtindex does not do this sort of union operation.  It is possible to
> use ogr2ogr to merge multiple datasets though it can be a bit tricky
> (see -append flag).
>
> Generalization for overviews is a more complex process.  It could be
> accomplished within PostGIS I think, or perhaps using a "real gis system"
> like GRASS.  Basically it is a fairly involved data processing operation.
>
> Best regards,
> -- 
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam, 
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | President OSGeo, http://osgeo.org 

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