FDO OGR <SupplementalSpatialContextInfo>

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FDO OGR <SupplementalSpatialContextInfo>

Carlos Lacerda
Hi Guys,

I have a simple question using SupplementalSpatialContextInfo in
FeatureSource on Mapguide.

I have a Map using WGS84 SRS and need overlays with a DGN Layer in UTM23s SRS.

All right, I create a map using UTM23s and DGN Layer is rendered Ok,
but now I need use a Map with WGS84 SRS and overlays this DGN layer,
so I try use the   <SupplementalSpatialContextInfo> tag in
FeatureSource definition without success, as DGN don´t have SRS inside
file I try the combinations below:

...  <SupplementalSpatialContextInfo>
    <Name>Corrego_Alegre_UTM_Zone_23S</Name>
<CoordinateSystem>PROJCS["Corrego_Alegre_UTM_Zone_23S",GEOGCS....</CoordinateSystem>
  </SupplementalSpatialContextInfo>...

...  <SupplementalSpatialContextInfo>
    <Name>default</Name>
    <CoordinateSystem>PROJCS["Corrego.UTM...</CoordinateSystem>
  </SupplementalSpatialContextInfo>...

...  <SupplementalSpatialContextInfo>
    <Name />
    <CoordinateSystem>PROJCS["Corrego.UTM-23S...</CoordinateSystem>
  </SupplementalSpatialContextInfo>....

I try the same above using WGS84 on <CoordinateSystem> tag without success :(

I stay using <SupplementalSpatialContextInfo> incorrectly or OGR don´t
support this feature or I going in wrong direction ?

I have a lot of SDF files with Features in UTM23s SRS in a Map using
WGS84 SRS and the map rendering fine without need
<SupplementalSpatialContextInfo> tag.

Thanks a lot for any sugestions.

--
Sds,
Carlos Lacerda
System Architect - CIAS
Brasil
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Re: FDO OGR <SupplementalSpatialContextInfo>

Jackie Ng
<Name> is the name of the spatial context (as returned by the OGR FDO provider)

<CoordinateSystem> is what will be used to replace the WKT of the spatial context (of the given name) as reported by the OGR FDO provider

If you get the <Name> incorrect, nothing actually gets overridden.

If the OGR provider doesn't report any spatial contexts (and ogrinfo gives you back coordinate system information), then it's most likely a bug in the OGR provider.

- Jackie
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Re: FDO OGR <SupplementalSpatialContextInfo>

Carlos Lacerda
Thank you for your reply Jackie, it is like I think, I tryed use
<Name> empty to try capture "Default" or any SRS to force a new SRS or
convert then, now these parameters are more clear to me after you
reply.

Because this when I use a SRS UTM23 originaly of the DGN, Map is
rendered correctly but if SRS is changed on Map the same cannot
convert data from DGN to SRS of Map to render data.

Using FDO Toolbox and fdo2fdo utilities, when I create a connection
using OGR driver the spatialcontext is empty with a DGN file.

With this tests using "FDO Toolbox(FDO.3.6 drivers )" and "fdo2fdo
(FDO.3.5 drivers)" returning spatialcontext empty in both this can be
really a Bug in OGR driver.

Where can I found more info about this?!

Thanks a lot.
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Re: FDO OGR <SupplementalSpatialContextInfo>

Jackie Ng
Empty as in 0 spatial contexts returned?

Does ogrinfo give you anything back about your DGNs? If ogrinfo returns nothing, I'd expect the same thing from the OGR provider.

- Jackie
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Re: FDO OGR <SupplementalSpatialContextInfo>

Carlos Lacerda
This is the return of ogrinfo:

[INFO: Open of `c:\temp\teo.dgn'
      using driver `DGN' successful.

Layer name: elements
Geometry: Unknown (any)
Feature Count: 40853
Extent: (231200.000000, 8017000.000000) - (240000.000000, 8027500.000000)
Layer SRS WKT:
(unknown)
Type: Integer (2.0)
Level: Integer (2.0)
GraphicGroup: Integer (4.0)
ColorIndex: Integer (3.0)
Weight: Integer (2.0)
Style: Integer (1.0)
EntityNum: Integer (0.0)
MSLink: Integer (0.0)
Text: String (0.0)]

OgrInfo return Extent and all fields correctly but without SRS.

In my research in Web I found some difficulty to set SRS for DGN files, this appear not common for DGN editors.

I don´t have any DGN editor to try SRID at this time but I try ASAP with Ogr2Ogr or other tool.

I think if not possible set SRS in DGN, a parameter to force this in driver config will be good as a workaround to this, because without this overlays using DGN layers on Mapguide using a Map with SRS different of the DGN will be impossible.

Thank you Jackie.