[postgis-devel] Oracle SDO_GEOMETRY vs PostGIS WKT

Jorge Arévalo jorge.arevalo at deimos-space.com
Tue Aug 24 15:27:28 PDT 2010


Hello,

I'm studying Oracle SDO_GEOMETRY type [1], and I find it really
tangled. But, AFAIK, the SFS standard [2] ST_Geometry is implemented
too, provided by ESRI [3]. And even a third ST_Geometry object,
provided by Oracle and basically equal to SDO_GEOMETRY type, is
available [4].

On the other hand, and please correct me if I'm wrong, PostGIS simply
implements the standard ST_Geometry type. I'm reading the SFS
documents [2], and the PostGIS documentation [5], and I find it
simpler to specify if the geometry is compound or not, if it has
holes... this is: the geometry's properties.

So, my questions, as a beginner, are:
- Why does Oracle use a tangled format like SDO_GEOMETRY, if they
could simply implement the easier standard? Any obvious reason I'm
missing? Apart from "we are a private company and define our own
formats".
- If I want to really understand spatial formats used in Oracle
Spatial, PostGIS... are the [2] standards the best source? I think
they are THE source... Am I right?

Thanks in advance, and best regards

-- 
Jorge Arévalo
http://gis4free.wordpress.com

[1] http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28400/sdo_objrelschema.htm#i1004087
[2] http://www.opengeospatial.org/standards/sfs
[3] http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?id=2709&pid=2704&topicname=The_ST_Geometry_storage_type
[4] http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28400/sdo_sql_mm.htm#CHDJHAFA
[5] http://postgis.refractions.net/docs/ch04.html



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