[gdal-dev] Problems doing spatial query with OGR

[Clay, Bruce]

Environment: Windows XP Visual Studio 2005, GDAL 1.5.0 with the C#  SWIG
bindings.

 

I am trying to determine the number of features within a geographic
bounding box for a specific time period.  The code I am using is shown
below

 

    OSGeo.OGR.Feature feature;

    int numFeatures;

 

    string sqlString = "select count(*) from " + tableName + " where " +
queryDefString;

 

    try

    {

        spatialFilter = Geometry.CreateFromWkt(wktGeometry);

    }

    catch (Exception except)

    {

        mLastErrorMsg = "Could not create patial filter from WKT
string";

    }

    if (spatialFilter != null)

    {

        try

        {

            dataLayer = dataSource.ExecuteSQL(sqlString, spatialFilter,
dialect);

 

            feature = dataLayer.GetNextFeature();

            if(feature != null)

            {
                numFeatures = feature. GetFieldAsInteger (0);

            }

                }

    }

 

The code executes without any error but appears to not use the spatial
filter at all because I get much lower results from an ArcObjects call
with the same bounding box and I get the same results from this code if
I pass a null value in as the spatial filter instead of the spatial
filter created from a WKT string.

 

The full sqlString is:

     "select count(*) from MODIS where

               DATE_TIME BETWEEN TO_DATE('2008-05-01 01:01:00',
'YYYY-MM-DD HH24:MI:SS') AND

                                 TO_DATE('2008-05-22 23:59:00',
'YYYY-MM-DD HH24:MI:SS')"

 

The wktGeometry string used to create the spatial filter is:

    "POLYGON((-83.7610299999997 35.1668499999996,

              -83.7610299999997 41.5608200000006,

              -76.9408000000003 41.5608200000006,

              -76.9408000000003 35.1668499999996,

              -83.7610299999997 35.1668499999996))"

 

As I mentioned above, I don't get any run time errors doing this just
the wrong results.

 

It appears to be filtering only on the date range provided.

 

Is there a specific order required in the WKT string?

 

Any other thoughts would be greatly appreciated.

 

Bruce

 




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