very large tile index

[Frank Warmerdam]

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,
-- 
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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