[mapserver-dev] Point layers with Oracle driver

[Fernando Simon]

Hi Daniel and David,
    Well, about the SDO_POINT. The Mapserver driver just read the point
data from SDO_POINT, from the Oracle Spatial manual (page 2.2, for point
example and figure 2-6): "SDO_ELEM_INFO and SDO_ORDINATES are both NULL,
as required if the SDO_POINT attribute is specified." And the SDO_POINT
topic in the manual hint that you can just store points using the
SDO_POINT attribute.
    Maybe you can force the use of the
SDO_GEOM.VALIDATE_GEOMETRY_WITH_CONTEXT function to verify if the
geometry is valid, if it returns true and Mapserver can't draw, we have
a bug :).
    David, about the kind of the point that you wrote, the Mapserver
can't draw it. I never head about it, I will read about it and other
things for release 11 to check new features. Now a question for core
developers, if I read angle data from database (like David wrote about
the point) can I set the angle attribute for the layer? Will work, the
angle?
    We can check about this special kind of data, but I believe that
Mapserver just need to draw the data/kinds/types defined in the 2-2
table for SDO_ELEM_INFO.
    Daniel, in my opinion the data that you report was wrong. You can
write in the Oracle forum (in the OTN page) about it, the developers of
the Oracle Spatial read and reply there.
    Best regards.

Fernando Simon

David Fuhry wrote:
> Daniel,
>
> Point ordinates wouldn't ever be in SDO_ELEM_INFO; it only stores
> metadata for how to interpret SDO_ORDINATES.
>
> I'm not sure what MapServer does, but Oracle MapViewer will render a
> point if the ordinates are stored in either the SDO_POINT or the
> SDO_ORDINATES substructure of SDO_GEOMETRY.
>
> Notably, 10g+ has a feature known as "oriented points", in which
> SDO_POINT is null, and the (x,y[,z]) point ordinates are stored in
> SDO_ORDINATES, and are followed by values (still in SDO_ORDINATES) which
> describe an angle, for obvious use in labeling.
>
> The correct behavior would be for MapServer to render the point at the
> location stored in SDO_ORDINATES iff the SDO_POINT is null.
>
> Thanks,
>
> Dave
>
>
> Daniel Morissette wrote:
>> Fernando,
>>
>> I've had someone report to me that when MapServer reads point layers
>> from Oracle, it works fine if the coordinates are stored in the
>> SDO_POINT, but it doesn't work if they are stored in SDO_ELEM_INFO or
>> SDO_ORDINATES which are apparently two other valid ways of storing
>> point data.
>>
>> Are you aware of this issue? Is there a way around it or do you have
>> any advice to provide to users who run into this problem?
>>
>> Thanks
>>
>> Daniel
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