[fdo-internals] How to get the four corners from a (raster data type) Feature

[Alfredo Muela-Romero]

Hi everyone again,

As an update to this topic, I am trying to solve this problem from a
different angle: getting through a command the FdoIGetSpatialContexts, and
accessing the FdoIEnvelope from FdoISpatialContextReader -> GetExtent and
converting the FdoByteArray to a FdoIGeometry.

By doing this, I can easily access to the extents of all the features.
However, if I cannot find the minX, minY, maxX and maxY values that are
expected.

A snippet of the code (based on SpatialContextTests::test_create_delete and
ArcSDETests::get_extent):

    FdoPtr < FdoIGetSpatialContexts > cmdGetSpatialContexts =
provider->createCommand< FdoIGetSpatialContexts >(
FdoCommandType_GetSpatialContexts );
    if (cmdGetSpatialContexts)
    {
        cmdGetSpatialContexts->SetActiveOnly( false );
        FdoPtr < FdoISpatialContextReader > scReader =
cmdGetSpatialContexts->Execute();

        while (scReader->ReadNext())
        {
            FdoStringP name = scReader->GetName();
            std::string str = std::string(static_cast<const char *> (name));

            // Get extent:
            FdoPtr<FdoByteArray> fgfArray = scReader->GetExtent();

            // Convert spatial context's extent to a FdoIEnvelope:
            FdoPtr<FdoFgfGeometryFactory> fgfFactory =
FdoFgfGeometryFactory::GetInstance();
            FdoPtr<FdoIGeometry> geom =
fgfFactory->CreateGeometryFromFgf(fgfArray);
            FdoPtr<FdoIEnvelope>  geomEnvelope = geom->GetEnvelope();

            // Convert envelope to minx/miny/maxx/maxy:
            double minx = geomEnvelope->GetMinX();
            double miny = geomEnvelope->GetMinY();
            double maxx = geomEnvelope->GetMaxX();
            double maxy = geomEnvelope->GetMaxY();
        }
    }



Thanks in advance,
Alfredo.



On Wed, Apr 10, 2013 at 12:20 PM, Alfredo Muela-Romero <alfredo.muela at pds.nl
> wrote:

> Hi everyone,
>
> Given a Feature class (in particular a raster data one, although I guess
> it can be generalized), I am trying to figure out the four corners
> (assuming same "z"-dimension).
>
> The approach is to execute a SQL command to retrieve MINX, MINY, MIZ,
> MAXX, MAXY, MAXZ from SDE.LAYERS with the appropriate owner and table. From
> those two coordinates that the z-dimension equality can be checked and the
> 4 corners defined.
>
> With that approach I get the expected values... usually. In other words,
> there are some features when the values from the query are hugely
> different. In order to validate the results, I use ArcCatalog to compare
> the Top, Left, Right and Bottom values from the Extent property.
>
> My questions are:
>   - can anyone shed some light on why is that happening?
>   - should I use a different approach to get this information?
>
>
> Many thanks,
> Alfredo.
>
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