[Gvsig_english] Question on GeoBD and Metadata when exporting toOracle
Wolfgang Qual
wolfgang.qual at muenchen.de
Thu Oct 15 11:25:13 CEST 2009
Hello Fran,
ok. Therefore, it should work... Thank you very much!
Best,
Wolfgang
Francisco José Peñarrubia schrieb:
> Hi Wolfgang.
>
> Spatial Indexes in local are used with local data. I mean, you can have
> your own spatial index in your hard disk. In case of Geospatial
> Databases, there is no local spatial index. The database manages its own
> spatial indexes, and is the responsability of the database admin. So, if
> the geospatial database is well configured, then, it's ok. Any spatial
> index is ok (for Oracle, Postgis, ArcSDE, mySQL, etc).
>
> Have fun.
>
> Fran Peñarrubia
> www.scolab.es
>
> Wolfgang Qual escribió:
>
>> Hello list, (hello Juan Lucas!)
>> some days ago, I posted some questions on GeoBD and Oracle Spatial to
>> this list - and got very good and detailed information.
>> Today, another question came to me (ok, a colleague asked me that
>> question): what type of spatial index is used (if any), if an oracle
>> spatial layer is loaded into gvSIG:
>> or: does gvSIG accept/make use of the R-tree-indexing? My colleague
>> told me that Oracle Quadtree indexing was used before and will be
>> replaced by R-tree.
>>
>> Any comment is appreciated.
>> best,
>> Wolfgang
>>
>>
>> ---8<----
>> Wolfgang Qual schrieb:
>>
>>> Hello Juan Lucas,
>>> thank you very much for this detailed information. I just found out
>>> that SDO_TOLERANCE_1 and .._2 are parameters within the ESRI
>>> application. Therefore, they refer to SDO_TOLERANCE values for X and
>>> Y. According to my colleague,
>>> ESRI sets those values to 0.0005. The tolerance parameter of GeoBD
>>> oracle export is set to 0.5 - does that mean that the tolerance is
>>> 0.5 meter? Can this be modified? As geometries of the common
>>> geodatabase are used in different departments with different
>>> applications, tolerance values should be identical, don't you think?
>>> Sorry, but I am not that well schooled in this oracle stuff...
>>>
>>> Best,
>>> Wolfgang
>>>
>>> ---8<---
>>> And resolution seems to be available in ESRI-software, too.
>>> Juan Lucas Dominguez Rubio schrieb:
>>>
>>>> Hello, Wolfgang.
>>>>
>>>> When you export a vector layer to Oracle Spatlai/Locator, the
>>>> sequence of actions is as follows:
>>>>
>>>> - if a table with the same name exists, it's deleted (dropped in
>>>> cascade mode). This also removes spatial indices associated with the
>>>> table
>>>> - the new table is created
>>>> - geometry metadata for this table name is removed (if existed)
>>>> - new geometry metadata is written in USER_SDO_GEOM_METADATA
>>>> - a spatial index on the geometry column is created
>>>> - table records are added (no commits here)
>>>> - a single final commit is performed
>>>>
>>>> The tolerance parameter in the metadata is always set to 0.5.
>>>> Dimension names are set to 'X', 'Y' and 'Z' (if needed) or
>>>> 'LONGITUDE' and 'LATITUDE'. Max. and min. values for X and Y are set
>>>> according to the layer's bounding box. Min. and max. values for 'Z'
>>>> (if needed) are always set to 0 and 100 (this is not very nice, but
>>>> has no bad effect since the Z value does not currently take part in
>>>> any geometric operation). Dimension names can be anything you want.
>>>> You could use 'BREITE' instead of 'LATITUDE', 'EASTING' instead of
>>>> 'X' or whatever.
>>>>
>>>> SDO_TOLERANCE_1 and SDO_TOLERANCE_2 refer to tolerance for X and Y
>>>> perhaps?
>>>>
>>>> Remember that the tolerance unit is implicit and depends on the
>>>> table's coordinate system (SRID). If the SRID corresponds to a
>>>> geodetic coordinate system (latitude, longitude), then the tolerance
>>>> is assumed to be expressed in meters. If the SRID corresponds to a
>>>> projected coordinate system (such as the German EPSG:3146X series)
>>>> then the tolerance is assumed to be expressed in the same unit used
>>>> by the coordinate system (usually meters). This also applies if the
>>>> SRID is NULL. According to this, it would be a bad idea to have a
>>>> table with geometries whose vertices are in latitude and longitude
>>>> and setting the SRID to NULL, because the tolerance (0.5) would
>>>> correspond to a few dozens of kilometers.
>>>>
>>>> The tolerance settings are very unlikely to have any effect when you
>>>> work with gvSIG because the application checks again the true
>>>> relationship between geometries after they have been converted to
>>>> the gvSIG geometry model. In other words: the 'select by rectangle'
>>>> tool should not behave in a strange way even if you have a bad
>>>> tolerance value. Of course you will see the effects of a bad
>>>> tolerance value from other applications or when you execute a SQL
>>>> statement directly against your database.
>>>>
>>>> So the metadata stored for a Oracle Spatial/Locator table are:
>>>>
>>>> - Owner
>>>> - Table name
>>>> - Geometry column name (the metadata record will be replicated for
>>>> several values because a table can have more than one geometry column)
>>>> - Dimension info (for each dimension: dimension name, max value, min
>>>> value, tolerance)
>>>> - SRID (possibly NULL)
>>>>
>>>> If you have a 3D vector layer (for example a 3D shapefile) I think
>>>> you will not notice the third dimension while you work with views
>>>> and layouts, but if you export that layer to your Oracle
>>>> Spatial/Locator database, it will be stored with a 3D geometry
>>>> column (you can see the number of dimensions of each using
>>>> Sqldeveloper for example)
>>>>
>>>> As you perhaps know, Oracle Spatial/Locator supports 4D geometries
>>>> (XYZT, I think Oracle normally uses the letter T instead of M for
>>>> the 4th dimension). When you open one of these tables with gvSIG,
>>>> the resulting layer is a 3D layer (4th dimension is discarded)
>>>>
>>>> I have never heard about a parameter called resolution in the table
>>>> metadata. Perhaps you are talking about some operations that allow
>>>> you to restrict the result by setting a min and max_resolution
>>>> value, but this is not connected to tables' metadata.
>>>>
>>>> I agree that it would be a good idea to let the user set the
>>>> metadata values.
>>>>
>>>> Regards,
>>>> Juan Lucas Domínguez Rubio
>>>> ---
>>>> Prodevelop SL, Valencia (España)
>>>> Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
>>>> http://www.prodevelop.es <http://www.prodevelop.es/>
>>>> ---
>>>>
>>>> ------------------------------------------------------------------------
>>>> *De:* gvsig_internacional-bounces at listserv.gva.es en nombre de
>>>> Wolfgang Qual
>>>> *Enviado el:* jue 24/09/2009 8:59
>>>> *Para:* Users and Developers mailing list
>>>> *Asunto:* [Gvsig_english] Question on GeoBD and Metadata when
>>>> exporting toOracle
>>>>
>>>> Hi list,
>>>> in our City administration, different GIS software is used to work with
>>>> spatial data. Among them, ArcMap and gvSIG allow to access a central
>>>> oracle spatial database. Thanks to the great GeoBD extension, accessing
>>>> that database via gvSIG is very comfortable, even exporting new layers
>>>> to the database is possible.
>>>> Yesterday, a colleague of mine who is in charge of the overall design of
>>>> the geodatabase asked me to provide some details on GeoBD's
>>>> capabilities. He asked me about metadata that is created by that
>>>> extension when exporting a shapefile to the oracle spatial database and
>>>> possibilities to set custom settings for the metadata. In this context,
>>>> he also talked about "tolerance" (SDO_TOLERANCE_1, SDO_TOLERANCE_2),
>>>> "resolution". I have no idea, whether GeoBD sets these values.
>>>> Therefore, I would be very happy, if someone of you (maybe the
>>>> developers from Prodevelop) could give me some details on the type and
>>>> values of metadata that is written to new oracle spatial layers. That
>>>> would be very great to have.
>>>>
>>>> Best regards and thank you very much for your help.
>>>> Wolfgang
>>>>
>>>> --
>>>> Wolfgang Qual
>>>> Landeshauptstadt München
>>>> Referat für Gesundheit und Umwelt
>>>> RGU-UW 11
>>>> Sg. 1 Gesundheits- und Umweltberichterstattung,
>>>> Energie und Klimaschutz
>>>> Bayerstr. 28a, 80335 München
>>>> Tel.: +49 (0)89 233-477 17
>>>> Fax.: +49 (0)89 233-477 05
>>>> E-Mail: wolfgang.qual at muenchen.de
>>>>
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>>>>
>>> --
>>> Wolfgang Qual
>>> Landeshauptstadt München
>>> Referat für Gesundheit und Umwelt
>>> RGU-UW 11
>>> Sg. 1 Gesundheits- und Umweltberichterstattung,
>>> Energie und Klimaschutz
>>> Bayerstr. 28a, 80335 München
>>> Tel.: +49 (0)89 233-477 17
>>> Fax.: +49 (0)89 233-477 05
>>> E-Mail: wolfgang.qual at muenchen.de
>>>
>> --
>>
>> *Wolfgang Qual
>>
>> * *Referat für Gesundheit und Umwelt*
>> Umweltschutz
>> Umweltvorsorge
>> RGU-UW 11
>>
>> Bayerstraße 28a
>> 80335 München
>>
>> Telefon +49 - 89 - 233 - 4 77 17
>> Telefax +49 - 89 - 233 - 4 77 05
>>
>> http://www.muenchen.de/umweltatlas
>> uw11.rgu at muenchen.de
>> Bitte beachten Sie die Hinweise zur elektronischen
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>>
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--
*Wolfgang Qual
* *Referat für Gesundheit und Umwelt*
Umweltschutz
Umweltvorsorge
RGU-UW 11
Bayerstraße 28a
80335 München
Telefon +49 - 89 - 233 - 4 77 17
Telefax +49 - 89 - 233 - 4 77 05
http://www.muenchen.de/umweltatlas
uw11.rgu at muenchen.de
Bitte beachten Sie die Hinweise zur elektronischen
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