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Hi Tom,<br>
<br>
To really answer this question, we have to make a benchmark between
bbox, wkt and wkb.<br>
<br>
But my feeling is that when we create the PostGIS modules, we will
need to use the native PostGIS geometries for performance. In the
same manner, using a native format for Shapely, theoretically would
cut down transformation time and keep only processing time during
spatial queries. But is the WKT the *real* native format for
Shapely? Or perhaps WKB? Or perhaps something internal? We have to
look into this.<br>
<br>
I think for the time, we should stick with the current storage model
for 0.1 release, and focus on this for later releases.<br>
<br>
Best regards,<br>
Angelos<br>
<br>
On 04/06/2011 10:01 PM, Tom Kralidis wrote:
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<br>
Hi: FYI in trunk, we have the requirement for storing geometries
in the format 'minx,miny,maxx,maxy'.<br>
<br>
This format is adhered to for:<br>
<br>
- importing metadata into the repository<br>
- searching metadata spatially (server.util.query_bbox() and
server.util.bbox_not_query())<br>
- presenting metadata<br>
<br>
For spatial searching, we are using Shapely [1] to perform
operations like intersects (ogc:BBOX) and disjoint
(ogc:Not/ogc:BBOX). We transform the geometry to wkt
(server.util.bbox2wkt) before passing to Shapely.<br>
<br>
Is there benefit to storing geometries as WKT in the repository?
Or WKB (maybe for better performance)? Or something else?<br>
<br>
The change would be easy to implement, the question is would this
be of value, in the context of the life cycle of catalog metadata
(import/search/present).<br>
<br>
Comments?<br>
<br>
..Tom<br>
<br>
[1] <a class="moz-txt-link-freetext" href="http://trac.gispython.org/lab/wiki/Shapely">http://trac.gispython.org/lab/wiki/Shapely</a><br>
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<br>
<pre class="moz-signature" cols="72">--
Angelos Tzotsos
Remote Sensing Laboratory
National Technical University of Athens
<a class="moz-txt-link-freetext" href="http://users.ntua.gr/tzotsos">http://users.ntua.gr/tzotsos</a></pre>
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