[gdal-dev] I couldn't use OGRCreateCoordinateTransformation

[Ahmet Temiz]

Thank you,
I am reading a shape file with line geometry in epsg:3857 projection.

.I create buffer from lines (polyCollect)
.union  them (unionCascaded)
. then convert it to multipolygon (poOGRMultiPolygon)
. then transform is necessary for each polygon in poPolygon from epsg:3857
to epsg:4326

  Here is the code:
    OGRGeometry * unionCascaded = polyCollect->UnionCascaded();
    OGRMultiPolygon * poOGRMultiPolygon= ( OGRMultiPolygon * )
unionCascaded;


    int NumberOfGeometries= poOGRMultiPolygon->getNumGeometries();

    OGRSpatialReference source;
    OGRSpatialReference dest;
    source.SetWellKnownGeogCS( "EPSG:3857" );
    dest.SetWellKnownGeogCS( "EPSG:4326" );

    OGRCoordinateTransformation* ct =
OGRCreateCoordinateTransformation(&source, &dest);

    for (int j=0; j< NumberOfGeometries ;j++    ){
        OGRGeometry * polyGeometry = poOGRMultiPolygon -> getGeometryRef(j);
        OGRPolygon *poPolygon= ( OGRPolygon *) polyGeometry;

        OGRErr err=poPolygon->transform(ct) ;

On Sun, Jun 20, 2021 at 11:02 AM Brad Hards <bradh at frogmouth.net> wrote:

> What is the `polyGeometry`?
>
>
>
> Can you try to generate a compilable, minimal, self-contained example that
> demonstrates the problem?
>
>
>
> Brad
>
>
>
> *From:* gdal-dev <gdal-dev-bounces at lists.osgeo.org> *On Behalf Of *Ahmet
> Temiz
> *Sent:* Sunday, 20 June 2021 5:56 PM
> *To:* gdal-dev <gdal-dev at lists.osgeo.org>
> *Subject:* [gdal-dev] I couldn't use OGRCreateCoordinateTransformation
>
>
>
> Hi,
>
> ..
>
>
>
>  source.SetWellKnownGeogCS( "EPSG:3857" );
>  dest.SetWellKnownGeogCS( "EPSG:4326" );
>
> OGRCoordinateTransformation* ct =
> OGRCreateCoordinateTransformation(&source, &dest);
>
>
>
> OGRPolygon *poPolygon= ( OGRPolygon *) polyGeometry;
>
> OGRErr err=poPolygon->transform(ct) ;  // it generates this error.
>
>
>
> ERROR 6: No translation for an empty SRS to PROJ.4 format is known.
>
>
>
> I think, this occurs, because I could not assign any SRS value to polygon
>
>
>
> How can I solve this problem?
>
>
>
> regards
>
>
>
> --
>
> Ahmet Temiz
> Jeoloji Müh.
> Afet ve Acil Durum Yönetimi Başkanlığı
> Deprem  Dairesi Başkanlığı
>
>
> ________________________
>
> Ahmet Temiz
> Geological Eng.
>
> Disaster and Emergency Management
> of Presidency
>


-- 
Ahmet Temiz
Jeoloji Müh.
Afet ve Acil Durum Yönetimi Başkanlığı
Deprem  Dairesi Başkanlığı


________________________

Ahmet Temiz
Geological Eng.

Disaster and Emergency Management
of Presidency
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