[fdo-users] RE: Fgf to Wkb

[maland]

After some more investigation I see that there are two problems here as Gavin
points out.

1 ) Fetching the geometries in FGF with GetGeometry using the OSGeo.ArcSDE
provider. As already mentioned, for the geometry referred to in my example,
this call takes 3-4 seconds. For reference, reading the exact same data
using the OSGeo.SHP provider, the call to GetGeometry takes 4 ms - a factor
of 1000! 

2 ) Converting the Geometry to Wkb. We have now implemented a version of
Fgf2Wkb based on source from OgrFdoUtil / SltGeomUtil. This approach is
roughly 400 times faster than using the GetWkb function in the FDO API. It
would have been nice if this utility function could be provided directly
through the FDO API.  

The first issue here is still bothering us. 

Henning


Greg Boone wrote:
> 
> NOTE: Even though the managed API is simply a wrapper around the unmanaged
> C++ API, the managed API's retrieval of the FGF byte array using
> GetGeometry() will always be slower than experienced using the unmanaged
> API directly. This is due to the fact that the underlying unmanaged FGF
> geometry cannot be referenced by const pointer as it could be in the case
> of unmanaged C++, but has to be copied to the managed byte array for
> return. So, the user always gets a copy of the byte array geometry rather
> than a reference to it.
> 
> Greg
> 
> -----Original Message-----
> From: fdo-users-bounces at lists.osgeo.org
> [mailto:fdo-users-bounces at lists.osgeo.org] On Behalf Of Gavin Cramer
> Sent: Monday, December 20, 2010 3:37 PM
> To: FDO Users Mail List
> Subject: RE: [fdo-users] RE: Fgf to Wkb
> 
> That does not sound right at all.  While using the FdoGeometry types won't
> be quite as fast as a direct binary conversion, I do not know of a reason
> for it to have anywhere near the performance problems that you report.
> 
> It sounds like there could be up to two problems:  fetching the geometry
> in FGF and converting the geometry to WKB.  The first one should be a
> direct binary conversion and even that is having a problem in this case.
> 
> If it is possible to share any of the data involved, I recommend filing an
> FDO defect so that it can be formally analysed and addressed.
> 
> Gavin
> 
> 
> -----Original Message-----
> From: fdo-users-bounces at lists.osgeo.org
> [mailto:fdo-users-bounces at lists.osgeo.org] On Behalf Of maland
> Sent: Monday, December 20, 2010 3:33 PM
> To: fdo-users at lists.osgeo.org
> Subject: [fdo-users] RE: Fgf to Wkb
> 
> 
> WKB byte array can be used to render the geometry.
> 
> We are a bit concerned about the performance of the FDO. For the specific
> geometry referred to in this post, even this call to GetGeometry need 3-4
> seconds to complete: 
> byte[] fgfBytes = reader.GetGeometry(p.Name);
> 
> We are using the OSGeo.ArcSDE provider.
> 
> Henning
> -- 
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