GDAL

Abstract base class for all geometry classes. More...
#include <ogr_geometry.h>
Public Member Functions  
OGRGeometry (const OGRGeometry &other)  
Copy constructor. More...  
OGRGeometry &  operator= (const OGRGeometry &other) 
Assignment operator. More...  
bool  operator== (const OGRGeometry &other) const 
Returns if two geometries are equal.  
bool  operator!= (const OGRGeometry &other) const 
Returns if two geometries are different.  
virtual int  getDimension () const =0 
Get the dimension of this object. More...  
virtual int  getCoordinateDimension () const 
Get the dimension of the coordinates in this object. More...  
int  CoordinateDimension () const 
Get the dimension of the coordinates in this object. More...  
virtual OGRBoolean  IsEmpty () const =0 
Returns TRUE (nonzero) if the object has no points. More...  
virtual OGRBoolean  IsValid () const 
Test if the geometry is valid. More...  
virtual OGRGeometry *  MakeValid (CSLConstList papszOptions=nullptr) const 
Attempts to make an invalid geometry valid without losing vertices. More...  
virtual OGRGeometry *  Normalize () const 
Attempts to bring geometry into normalized/canonical form. More...  
virtual OGRBoolean  IsSimple () const 
Test if the geometry is simple. More...  
OGRBoolean  Is3D () const 
OGRBoolean  IsMeasured () const 
virtual OGRBoolean  IsRing () const 
Test if the geometry is a ring. More...  
virtual void  empty ()=0 
Clear geometry information. More...  
virtual OGRGeometry *  clone () const =0 
Make a copy of this object. More...  
virtual void  getEnvelope (OGREnvelope *psEnvelope) const =0 
Computes and returns the bounding envelope for this geometry in the passed psEnvelope structure. More...  
virtual void  getEnvelope (OGREnvelope3D *psEnvelope) const =0 
Computes and returns the bounding envelope (3D) for this geometry in the passed psEnvelope structure. More...  
virtual size_t  WkbSize () const =0 
Returns size of related binary representation. More...  
OGRErr  importFromWkb (const GByte *, size_t=static_cast< size_t >(1), OGRwkbVariant=wkbVariantOldOgc) 
Assign geometry from well known binary data. More...  
virtual OGRErr  importFromWkb (const unsigned char *, size_t, OGRwkbVariant, size_t &nBytesConsumedOut)=0 
Assign geometry from well known binary data. More...  
virtual OGRErr  exportToWkb (OGRwkbByteOrder, unsigned char *, OGRwkbVariant=wkbVariantOldOgc) const =0 
Convert a geometry into well known binary format. More...  
virtual OGRErr  importFromWkt (const char **ppszInput)=0 
Assign geometry from well known text data. More...  
OGRErr  importFromWkt (char **ppszInput) 
Deprecated. More...  
OGRErr  exportToWkt (char **ppszDstText, OGRwkbVariant=wkbVariantOldOgc) const 
Convert a geometry into well known text format. More...  
virtual std::string  exportToWkt (const OGRWktOptions &opts=OGRWktOptions(), OGRErr *err=nullptr) const =0 
Export a WKT geometry. More...  
virtual OGRwkbGeometryType  getGeometryType () const =0 
Fetch geometry type. More...  
OGRwkbGeometryType  getIsoGeometryType () const 
Get the geometry type that conforms with ISO SQL/MM Part3. More...  
virtual const char *  getGeometryName () const =0 
Fetch WKT name for geometry type. More...  
void  dumpReadable (FILE *, const char *=nullptr, CSLConstList papszOptions=nullptr) const 
Dump geometry in well known text format to indicated output file. More...  
std::string  dumpReadable (const char *=nullptr, CSLConstList papszOptions=nullptr) const 
Dump geometry in well known text format to indicated output file. More...  
virtual void  flattenTo2D ()=0 
Convert geometry to strictly 2D. More...  
virtual char *  exportToGML (const char *const *papszOptions=nullptr) const 
Convert a geometry into GML format. More...  
virtual char *  exportToKML () const 
Convert a geometry into KML format. More...  
virtual char *  exportToJson () const 
Convert a geometry into GeoJSON format. More...  
virtual void  accept (IOGRGeometryVisitor *visitor)=0 
Accept a visitor. More...  
virtual void  accept (IOGRConstGeometryVisitor *visitor) const =0 
Accept a visitor. More...  
virtual GEOSGeom  exportToGEOS (GEOSContextHandle_t hGEOSCtxt) const 
Returns a GEOSGeom object corresponding to the geometry. More...  
virtual OGRBoolean  hasCurveGeometry (int bLookForNonLinear=FALSE) const 
Returns if this geometry is or has curve geometry. More...  
virtual OGRGeometry *  getCurveGeometry (const char *const *papszOptions=nullptr) const 
Return curve version of this geometry. More...  
virtual OGRGeometry *  getLinearGeometry (double dfMaxAngleStepSizeDegrees=0, const char *const *papszOptions=nullptr) const 
Return, possibly approximate, noncurve version of this geometry. More...  
virtual void  closeRings () 
Force rings to be closed. More...  
virtual void  setCoordinateDimension (int nDimension) 
Set the coordinate dimension. More...  
virtual void  set3D (OGRBoolean bIs3D) 
Add or remove the Z coordinate dimension. More...  
virtual void  setMeasured (OGRBoolean bIsMeasured) 
Add or remove the M coordinate dimension. More...  
virtual void  assignSpatialReference (OGRSpatialReference *poSR) 
Assign spatial reference to this object. More...  
OGRSpatialReference *  getSpatialReference (void) const 
Returns spatial reference system for object. More...  
virtual OGRErr  transform (OGRCoordinateTransformation *poCT)=0 
Apply arbitrary coordinate transformation to geometry. More...  
OGRErr  transformTo (OGRSpatialReference *poSR) 
Transform geometry to new spatial reference system. More...  
virtual void  segmentize (double dfMaxLength) 
Modify the geometry such it has no segment longer then the given distance. More...  
virtual OGRBoolean  Intersects (const OGRGeometry *) const 
Do these features intersect? More...  
virtual OGRBoolean  Equals (const OGRGeometry *) const =0 
Returns TRUE if two geometries are equivalent. More...  
virtual OGRBoolean  Disjoint (const OGRGeometry *) const 
Test for disjointness. More...  
virtual OGRBoolean  Touches (const OGRGeometry *) const 
Test for touching. More...  
virtual OGRBoolean  Crosses (const OGRGeometry *) const 
Test for crossing. More...  
virtual OGRBoolean  Within (const OGRGeometry *) const 
Test for containment. More...  
virtual OGRBoolean  Contains (const OGRGeometry *) const 
Test for containment. More...  
virtual OGRBoolean  Overlaps (const OGRGeometry *) const 
Test for overlap. More...  
virtual OGRGeometry *  Boundary () const 
Compute boundary. More...  
virtual double  Distance (const OGRGeometry *) const 
Compute distance between two geometries. More...  
virtual OGRGeometry *  ConvexHull () const 
Compute convex hull. More...  
virtual OGRGeometry *  ConcaveHull (double dfRatio, bool bAllowHoles) const 
Compute "concave hull" of a geometry. More...  
virtual OGRGeometry *  Buffer (double dfDist, int nQuadSegs=30) const 
Compute buffer of geometry. More...  
virtual OGRGeometry *  Intersection (const OGRGeometry *) const 
Compute intersection. More...  
virtual OGRGeometry *  Union (const OGRGeometry *) const 
Compute union. More...  
virtual OGRGeometry *  UnionCascaded () const 
Compute union using cascading. More...  
virtual OGRGeometry *  Difference (const OGRGeometry *) const 
Compute difference. More...  
virtual OGRGeometry *  SymDifference (const OGRGeometry *) const 
Compute symmetric difference. More...  
virtual OGRErr  Centroid (OGRPoint *poPoint) const 
Compute the geometry centroid. More...  
virtual OGRGeometry *  Simplify (double dTolerance) const 
Simplify the geometry. More...  
OGRGeometry *  SimplifyPreserveTopology (double dTolerance) const 
Simplify the geometry while preserving topology. More...  
virtual OGRGeometry *  DelaunayTriangulation (double dfTolerance, int bOnlyEdges) const 
Return a Delaunay triangulation of the vertices of the geometry. More...  
virtual OGRGeometry *  Polygonize () const 
Polygonizes a set of sparse edges. More...  
virtual double  Distance3D (const OGRGeometry *poOtherGeom) const 
Returns the 3D distance between two geometries. More...  
virtual void  swapXY () 
Swap x and y coordinates. More...  
OGRPoint *  toPoint () 
Downcast to OGRPoint*. More...  
const OGRPoint *  toPoint () const 
Downcast to OGRPoint*. More...  
OGRCurve *  toCurve () 
Downcast to OGRCurve*. More...  
const OGRCurve *  toCurve () const 
Downcast to OGRCurve*. More...  
OGRSimpleCurve *  toSimpleCurve () 
Downcast to OGRSimpleCurve*. More...  
const OGRSimpleCurve *  toSimpleCurve () const 
Downcast to OGRSimpleCurve*. More...  
OGRLineString *  toLineString () 
Downcast to OGRLineString*. More...  
const OGRLineString *  toLineString () const 
Downcast to OGRLineString*. More...  
OGRLinearRing *  toLinearRing () 
Downcast to OGRLinearRing*. More...  
const OGRLinearRing *  toLinearRing () const 
Downcast to OGRLinearRing*. More...  
OGRCircularString *  toCircularString () 
Downcast to OGRCircularString*. More...  
const OGRCircularString *  toCircularString () const 
Downcast to OGRCircularString*. More...  
OGRCompoundCurve *  toCompoundCurve () 
Downcast to OGRCompoundCurve*. More...  
const OGRCompoundCurve *  toCompoundCurve () const 
Downcast to OGRCompoundCurve*. More...  
OGRSurface *  toSurface () 
Downcast to OGRSurface*. More...  
const OGRSurface *  toSurface () const 
Downcast to OGRSurface*. More...  
OGRPolygon *  toPolygon () 
Downcast to OGRPolygon*. More...  
const OGRPolygon *  toPolygon () const 
Downcast to OGRPolygon*. More...  
OGRTriangle *  toTriangle () 
Downcast to OGRTriangle*. More...  
const OGRTriangle *  toTriangle () const 
Downcast to OGRTriangle*. More...  
OGRCurvePolygon *  toCurvePolygon () 
Downcast to OGRCurvePolygon*. More...  
const OGRCurvePolygon *  toCurvePolygon () const 
Downcast to OGRCurvePolygon*. More...  
OGRGeometryCollection *  toGeometryCollection () 
Downcast to OGRGeometryCollection*. More...  
const OGRGeometryCollection *  toGeometryCollection () const 
Downcast to OGRGeometryCollection*. More...  
OGRMultiPoint *  toMultiPoint () 
Downcast to OGRMultiPoint*. More...  
const OGRMultiPoint *  toMultiPoint () const 
Downcast to OGRMultiPoint*. More...  
OGRMultiLineString *  toMultiLineString () 
Downcast to OGRMultiLineString*. More...  
const OGRMultiLineString *  toMultiLineString () const 
Downcast to OGRMultiLineString*. More...  
OGRMultiPolygon *  toMultiPolygon () 
Downcast to OGRMultiPolygon*. More...  
const OGRMultiPolygon *  toMultiPolygon () const 
Downcast to OGRMultiPolygon*. More...  
OGRMultiCurve *  toMultiCurve () 
Downcast to OGRMultiCurve*. More...  
const OGRMultiCurve *  toMultiCurve () const 
Downcast to OGRMultiCurve*. More...  
OGRMultiSurface *  toMultiSurface () 
Downcast to OGRMultiSurface*. More...  
const OGRMultiSurface *  toMultiSurface () const 
Downcast to OGRMultiSurface*. More...  
OGRPolyhedralSurface *  toPolyhedralSurface () 
Downcast to OGRPolyhedralSurface*. More...  
const OGRPolyhedralSurface *  toPolyhedralSurface () const 
Downcast to OGRPolyhedralSurface*. More...  
OGRTriangulatedSurface *  toTriangulatedSurface () 
Downcast to OGRTriangulatedSurface*. More...  
const OGRTriangulatedSurface *  toTriangulatedSurface () const 
Downcast to OGRTriangulatedSurface*. More...  
Static Public Member Functions  
static GEOSContextHandle_t  createGEOSContext () 
Create a new GEOS context. More...  
static void  freeGEOSContext (GEOSContextHandle_t hGEOSCtxt) 
Destroy a GEOS context. More...  
static OGRGeometryH  ToHandle (OGRGeometry *poGeom) 
Convert a OGRGeometry* to a OGRGeometryH. More...  
static OGRGeometry *  FromHandle (OGRGeometryH hGeom) 
Convert a OGRGeometryH to a OGRGeometry*. More...  
Abstract base class for all geometry classes.
Some spatial analysis methods require that OGR is built on the GEOS library to work properly. The precise meaning of methods that describe spatial relationships between geometries is described in the SFCOM, or other simple features interface specifications, like "OpenGISÂ® Implementation Specification for Geographic information  Simple feature access  Part 1: Common architecture": OGC 06103r4
In GDAL 2.0, the hierarchy of classes has been extended with (working draft) ISO SQL/MM Part 3 (ISO/IEC 132493) curve geometries : CIRCULARSTRING (OGRCircularString), COMPOUNDCURVE (OGRCompoundCurve), CURVEPOLYGON (OGRCurvePolygon), MULTICURVE (OGRMultiCurve) and MULTISURFACE (OGRMultiSurface).
OGRGeometry::OGRGeometry  (  const OGRGeometry &  other  ) 
Copy constructor.
Note: before GDAL 2.1, only the default implementation of the constructor existed, which could be unsafe to use.

pure virtual 
Accept a visitor.
Implemented in OGRPoint, OGRLineString, OGRLinearRing, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRTriangle, OGRGeometryCollection, OGRMultiSurface, OGRMultiPolygon, OGRPolyhedralSurface, OGRTriangulatedSurface, OGRMultiPoint, OGRMultiCurve, and OGRMultiLineString.

pure virtual 
Accept a visitor.
Implemented in OGRPoint, OGRLineString, OGRLinearRing, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRTriangle, OGRGeometryCollection, OGRMultiSurface, OGRMultiPolygon, OGRPolyhedralSurface, OGRTriangulatedSurface, OGRMultiPoint, OGRMultiCurve, and OGRMultiLineString.

virtual 
Assign spatial reference to this object.
Any existing spatial reference is replaced, but under no circumstances does this result in the object being reprojected. It is just changing the interpretation of the existing geometry. Note that assigning a spatial reference increments the reference count on the OGRSpatialReference, but does not copy it.
Starting with GDAL 2.3, this will also assign the spatial reference to potential subgeometries of the geometry (OGRGeometryCollection, OGRCurvePolygon/OGRPolygon, OGRCompoundCurve, OGRPolyhedralSurface and their derived classes).
This is similar to the SFCOM IGeometry::put_SpatialReference() method.
This method is the same as the C function OGR_G_AssignSpatialReference().
poSR  new spatial reference system to apply. 
Reimplemented in OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

virtual 
Compute boundary.
A new geometry object is created and returned containing the boundary of the geometry on which the method is invoked.
This method is the same as the C function OGR_G_Boundary().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.

virtual 
Compute buffer of geometry.
Builds a new geometry containing the buffer region around the geometry on which it is invoked. The buffer is a polygon containing the region within the buffer distance of the original geometry.
Some buffer sections are properly described as curves, but are converted to approximate polygons. The nQuadSegs parameter can be used to control how many segments should be used to define a 90 degree curve  a quadrant of a circle. A value of 30 is a reasonable default. Large values result in large numbers of vertices in the resulting buffer geometry while small numbers reduce the accuracy of the result.
This method is the same as the C function OGR_G_Buffer().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
dfDist  the buffer distance to be applied. Should be expressed into the same unit as the coordinates of the geometry. 
nQuadSegs  the number of segments used to approximate a 90 degree (quadrant) of curvature. 
Compute the geometry centroid.
The centroid location is applied to the passed in OGRPoint object. The centroid is not necessarily within the geometry.
This method relates to the SFCOM ISurface::get_Centroid() method however the current implementation based on GEOS can operate on other geometry types such as multipoint, linestring, geometrycollection such as multipolygons. OGC SF SQL 1.1 defines the operation for surfaces (polygons). SQL/MMPart 3 defines the operation for surfaces and multisurfaces (multipolygons).
This function is the same as the C function OGR_G_Centroid().
This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

pure virtual 
Make a copy of this object.
This method relates to the SFCOM IGeometry::clone() method.
This method is the same as the C function OGR_G_Clone().
Implemented in OGRPoint, OGRLineString, OGRLinearRing, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRTriangle, OGRGeometryCollection, OGRMultiSurface, OGRMultiPolygon, OGRPolyhedralSurface, OGRTriangulatedSurface, OGRMultiPoint, OGRMultiCurve, OGRMultiLineString, OGRCurve, OGRSimpleCurve, and OGRSurface.

virtual 
Force rings to be closed.
If this geometry, or any contained geometries has polygon rings that are not closed, they will be closed by adding the starting point at the end.
Reimplemented in OGRLinearRing, OGRPolygon, and OGRGeometryCollection.

virtual 
Compute "concave hull" of a geometry.
The concave hull is fully contained within the convex hull and also contains all the points of the input, but in a smaller area. The area ratio is the ratio of the area of the convex hull and the concave hull. Frequently used to convert a multipoint into a polygonal area. that contains all the points in the input Geometry.
A new geometry object is created and returned containing the concave hull of the geometry on which the method is invoked.
This method is the same as the C function OGR_G_ConcaveHull().
This method is built on the GEOS >= 3.11 library If OGR is built without the GEOS >= 3.11 librray, this method will always fail, issuing a CPLE_NotSupported error.
dfRatio  Ratio of the area of the convex hull and the concave hull. 
bAllowHoles  Whether holes are allowed. 

virtual 
Test for containment.
Tests if actual geometry object contains the passed geometry.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_Contains().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the geometry to compare to this geometry. 
Reimplemented in OGRCurvePolygon.

virtual 
Compute convex hull.
A new geometry object is created and returned containing the convex hull of the geometry on which the method is invoked.
This method is the same as the C function OGR_G_ConvexHull().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
int OGRGeometry::CoordinateDimension  (  )  const 
Get the dimension of the coordinates in this object.
This method is the same as the C function OGR_G_CoordinateDimension().

static 
Create a new GEOS context.

virtual 
Test for crossing.
Tests if this geometry and the other passed into the method are crossing.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_Crosses().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the geometry to compare to this geometry. 

virtual 
Return a Delaunay triangulation of the vertices of the geometry.
This function is the same as the C function OGR_G_DelaunayTriangulation().
This function is built on the GEOS library, v3.4 or above. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.
dfTolerance  optional snapping tolerance to use for improved robustness 
bOnlyEdges  if TRUE, will return a MULTILINESTRING, otherwise it will return a GEOMETRYCOLLECTION containing triangular POLYGONs. 

virtual 
Compute difference.
Generates a new geometry which is the region of this geometry with the region of the second geometry removed.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_Difference().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the other geometry removed from "this" geometry. 

virtual 
Test for disjointness.
Tests if this geometry and the other passed into the method are disjoint.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_Disjoint().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the geometry to compare to this geometry. 

virtual 
Compute distance between two geometries.
Returns the shortest distance between the two geometries. The distance is expressed into the same unit as the coordinates of the geometries.
This method is the same as the C function OGR_G_Distance().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the other geometry to compare against. 

virtual 
Returns the 3D distance between two geometries.
The distance is expressed into the same unit as the coordinates of the geometries.
This method is built on the SFCGAL library, check it for the definition of the geometry operation. If OGR is built without the SFCGAL library, this method will always return 1.0
This function is the same as the C function OGR_G_Distance3D().
std::string OGRGeometry::dumpReadable  (  const char *  pszPrefix = nullptr , 
CSLConstList  papszOptions = nullptr 

)  const 
Dump geometry in well known text format to indicated output file.
A few options can be defined to change the default dump :
pszPrefix  the prefix to put on each line of output. 
papszOptions  NULL terminated list of options (may be NULL) 
void OGRGeometry::dumpReadable  (  FILE *  fp, 
const char *  pszPrefix = nullptr , 

CSLConstList  papszOptions = nullptr 

)  const 
Dump geometry in well known text format to indicated output file.
A few options can be defined to change the default dump :
This method is the same as the C function OGR_G_DumpReadable().
fp  the text file to write the geometry to. 
pszPrefix  the prefix to put on each line of output. 
papszOptions  NULL terminated list of options (may be NULL) 

pure virtual 
Clear geometry information.
This restores the geometry to its initial state after construction, and before assignment of actual geometry.
This method relates to the SFCOM IGeometry::Empty() method.
This method is the same as the C function OGR_G_Empty().
Implemented in OGRPoint, OGRSimpleCurve, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

pure virtual 
Returns TRUE if two geometries are equivalent.
This operation implements the SQL/MM ST_OrderingEquals() operation.
The comparison is done in a structural way, that is to say that the geometry types must be identical, as well as the number and ordering of subgeometries and vertices. Or equivalently, two geometries are considered equal by this method if their WKT/WKB representation is equal. Note: this must be distinguished for equality in a spatial way (which is the purpose of the ST_Equals() operation).
This method is the same as the C function OGR_G_Equals().
Implemented in OGRPoint, OGRSimpleCurve, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

virtual 
Returns a GEOSGeom object corresponding to the geometry.
hGEOSCtxt  GEOS context 

virtual 
Convert a geometry into GML format.
The GML geometry is expressed directly in terms of GML basic data types assuming the this is available in the gml namespace. The returned string should be freed with CPLFree() when no longer required.
The supported options in OGR 1.8.0 are :
This method is the same as the C function OGR_G_ExportToGMLEx().
papszOptions  NULLterminated list of options. 

virtual 
Convert a geometry into GeoJSON format.
The returned string should be freed with CPLFree() when no longer required.
This method is the same as the C function OGR_G_ExportToJson().

virtual 
Convert a geometry into KML format.
The returned string should be freed with CPLFree() when no longer required.
This method is the same as the C function OGR_G_ExportToKML().

pure virtual 
Convert a geometry into well known binary format.
This method relates to the SFCOM IWks::ExportToWKB() method.
This method is the same as the C function OGR_G_ExportToWkb() or OGR_G_ExportToIsoWkb(), depending on the value of eWkbVariant.
eByteOrder  One of wkbXDR or wkbNDR indicating MSB or LSB byte order respectively. 
pabyData  a buffer into which the binary representation is written. This buffer must be at least OGRGeometry::WkbSize() byte in size. 
eWkbVariant  What standard to use when exporting geometries with three dimensions (or more). The default wkbVariantOldOgc is the historical OGR variant. wkbVariantIso is the variant defined in ISO SQL/MM and adopted by OGC for SFSQL 1.2. 
Implemented in OGRPoint, OGRSimpleCurve, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRGeometryCollection, and OGRPolyhedralSurface.
OGRErr OGRGeometry::exportToWkt  (  char **  ppszDstText, 
OGRwkbVariant  variant = wkbVariantOldOgc 

)  const 
Convert a geometry into well known text format.
This method relates to the SFCOM IWks::ExportToWKT() method.
This method is the same as the C function OGR_G_ExportToWkt().
ppszDstText  a text buffer is allocated by the program, and assigned to the passed pointer. After use, *ppszDstText should be freed with CPLFree(). 
variant  the specification that must be conformed too :


pure virtual 
Export a WKT geometry.
opts  Output options. 
err  Pointer to error code, if desired. 
Implemented in OGRPoint, OGRSimpleCurve, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRGeometryCollection, OGRMultiSurface, OGRMultiPolygon, OGRPolyhedralSurface, OGRMultiPoint, OGRMultiCurve, OGRMultiLineString, OGRPoint, OGRSimpleCurve, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRGeometryCollection, OGRMultiSurface, OGRMultiPolygon, OGRPolyhedralSurface, OGRMultiPoint, OGRMultiCurve, and OGRMultiLineString.

pure virtual 
Convert geometry to strictly 2D.
In a sense this converts all Z coordinates to 0.0.
This method is the same as the C function OGR_G_FlattenTo2D().
Implemented in OGRPoint, OGRSimpleCurve, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

static 
Destroy a GEOS context.
hGEOSCtxt  GEOS context 

inlinestatic 
Convert a OGRGeometryH to a OGRGeometry*.

virtual 
Get the dimension of the coordinates in this object.
This method is the same as the C function OGR_G_GetCoordinateDimension().

virtual 
Return curve version of this geometry.
Returns a geometry that has possibly CIRCULARSTRING, COMPOUNDCURVE, CURVEPOLYGON, MULTICURVE or MULTISURFACE in it, by deapproximating curve geometries.
If the geometry has no curve portion, the returned geometry will be a clone of it.
The ownership of the returned geometry belongs to the caller.
The reverse method is OGRGeometry::getLinearGeometry().
This function is the same as C function OGR_G_GetCurveGeometry().
papszOptions  options as a nullterminated list of strings. Unused for now. Must be set to NULL. 
Reimplemented in OGRLineString, OGRPolygon, and OGRGeometryCollection.

pure virtual 
Get the dimension of this object.
This method corresponds to the SFCOM IGeometry::GetDimension() method. It indicates the dimension of the object, but does not indicate the dimension of the underlying space (as indicated by OGRGeometry::getCoordinateDimension()).
This method is the same as the C function OGR_G_GetDimension().
Implemented in OGRPoint, OGRCurve, OGRCurvePolygon, OGRGeometryCollection, OGRMultiSurface, OGRPolyhedralSurface, OGRMultiPoint, and OGRMultiCurve.

pure virtual 
Computes and returns the bounding envelope for this geometry in the passed psEnvelope structure.
This method is the same as the C function OGR_G_GetEnvelope().
psEnvelope  the structure in which to place the results. 
Implemented in OGRPoint, OGRSimpleCurve, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

pure virtual 
Computes and returns the bounding envelope (3D) for this geometry in the passed psEnvelope structure.
This method is the same as the C function OGR_G_GetEnvelope3D().
psEnvelope  the structure in which to place the results. 
Implemented in OGRPoint, OGRSimpleCurve, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

pure virtual 
Fetch WKT name for geometry type.
There is no SFCOM analog to this method.
This method is the same as the C function OGR_G_GetGeometryName().
Implemented in OGRPoint, OGRLineString, OGRLinearRing, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRTriangle, OGRGeometryCollection, OGRMultiSurface, OGRMultiPolygon, OGRPolyhedralSurface, OGRTriangulatedSurface, OGRMultiPoint, OGRMultiCurve, and OGRMultiLineString.

pure virtual 
Fetch geometry type.
Note that the geometry type may include the 2.5D flag. To get a 2D flattened version of the geometry type apply the wkbFlatten() macro to the return result.
This method is the same as the C function OGR_G_GetGeometryType().
Implemented in OGRPoint, OGRLineString, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRTriangle, OGRGeometryCollection, OGRMultiSurface, OGRMultiPolygon, OGRPolyhedralSurface, OGRTriangulatedSurface, OGRMultiPoint, OGRMultiCurve, and OGRMultiLineString.
OGRwkbGeometryType OGRGeometry::getIsoGeometryType  (  )  const 
Get the geometry type that conforms with ISO SQL/MM Part3.

virtual 
Return, possibly approximate, noncurve version of this geometry.
Returns a geometry that has no CIRCULARSTRING, COMPOUNDCURVE, CURVEPOLYGON, MULTICURVE or MULTISURFACE in it, by approximating curve geometries.
The ownership of the returned geometry belongs to the caller.
The reverse method is OGRGeometry::getCurveGeometry().
This method is the same as the C function OGR_G_GetLinearGeometry().
dfMaxAngleStepSizeDegrees  the largest step in degrees along the arc, zero to use the default setting. 
papszOptions  options as a nullterminated list of strings. See OGRGeometryFactory::curveToLineString() for valid options. 
Reimplemented in OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, and OGRGeometryCollection.

inline 
Returns spatial reference system for object.
This method relates to the SFCOM IGeometry::get_SpatialReference() method.
This method is the same as the C function OGR_G_GetSpatialReference().

virtual 
Returns if this geometry is or has curve geometry.
Returns if a geometry is, contains or may contain a CIRCULARSTRING, COMPOUNDCURVE, CURVEPOLYGON, MULTICURVE or MULTISURFACE.
If bLookForNonLinear is set to TRUE, it will be actually looked if the geometry or its subgeometries are or contain a nonlinear geometry in them. In which case, if the method returns TRUE, it means that getLinearGeometry() would return an approximate version of the geometry. Otherwise, getLinearGeometry() would do a conversion, but with just converting container type, like COMPOUNDCURVE > LINESTRING, MULTICURVE > MULTILINESTRING or MULTISURFACE > MULTIPOLYGON, resulting in a "lossless" conversion.
This method is the same as the C function OGR_G_HasCurveGeometry().
bLookForNonLinear  set it to TRUE to check if the geometry is or contains a CIRCULARSTRING. 
Reimplemented in OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRGeometryCollection, OGRMultiSurface, OGRMultiPolygon, OGRPolyhedralSurface, OGRMultiPoint, OGRMultiCurve, and OGRMultiLineString.
OGRErr OGRGeometry::importFromWkb  (  const GByte *  pabyData, 
size_t  nSize = static_cast<size_t>(1) , 

OGRwkbVariant  eWkbVariant = wkbVariantOldOgc 

) 
Assign geometry from well known binary data.
The object must have already been instantiated as the correct derived type of geometry object to match the binaries type. This method is used by the OGRGeometryFactory class, but not normally called by application code.
This method relates to the SFCOM IWks::ImportFromWKB() method.
This method is the same as the C function OGR_G_ImportFromWkb().
pabyData  the binary input data. 
nSize  the size of pabyData in bytes, or 1 if not known. 
eWkbVariant  if wkbVariantPostGIS1, special interpretation is done for curve geometries code 

pure virtual 
Assign geometry from well known binary data.
The object must have already been instantiated as the correct derived type of geometry object to match the binaries type. This method is used by the OGRGeometryFactory class, but not normally called by application code.
This method relates to the SFCOM IWks::ImportFromWKB() method.
This method is the same as the C function OGR_G_ImportFromWkb().
pabyData  the binary input data. 
nSize  the size of pabyData in bytes, or 1 if not known. 
eWkbVariant  if wkbVariantPostGIS1, special interpretation is done for curve geometries code 
nBytesConsumedOut  output parameter. Number of bytes consumed. 
Implemented in OGRPoint, OGRSimpleCurve, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRTriangle, OGRGeometryCollection, and OGRPolyhedralSurface.

inline 
Deprecated.

pure virtual 
Assign geometry from well known text data.
The object must have already been instantiated as the correct derived type of geometry object to match the text type. This method is used by the OGRGeometryFactory class, but not normally called by application code.
This method relates to the SFCOM IWks::ImportFromWKT() method.
This method is the same as the C function OGR_G_ImportFromWkt().
ppszInput  pointer to a pointer to the source text. The pointer is updated to pointer after the consumed text. 
Implemented in OGRPoint, OGRSimpleCurve, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRGeometryCollection, OGRMultiSurface, OGRPolyhedralSurface, OGRMultiPoint, OGRMultiCurve, OGRPoint, OGRSimpleCurve, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRGeometryCollection, OGRMultiSurface, OGRPolyhedralSurface, OGRMultiPoint, and OGRMultiCurve.

virtual 
Compute intersection.
Generates a new geometry which is the region of intersection of the two geometries operated on. The Intersects() method can be used to test if two geometries intersect.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_Intersection().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the other geometry intersected with "this" geometry. 

virtual 
Do these features intersect?
Determines whether two geometries intersect. If GEOS is enabled, then this is done in rigorous fashion otherwise TRUE is returned if the envelopes (bounding boxes) of the two geometries overlap.
The poOtherGeom argument may be safely NULL, but in this case the method will always return TRUE. That is, a NULL geometry is treated as being everywhere.
This method is the same as the C function OGR_G_Intersects().
poOtherGeom  the other geometry to test against. 
Reimplemented in OGRPoint, and OGRCurvePolygon.

inline 
Returns whether the geometry has a Z component.

pure virtual 
Returns TRUE (nonzero) if the object has no points.
Normally this returns FALSE except between when an object is instantiated and points have been assigned.
This method relates to the SFCOM IGeometry::IsEmpty() method.
Implemented in OGRPoint, OGRSimpleCurve, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

inline 
Returns whether the geometry has a M component.

virtual 
Test if the geometry is a ring.
This method is the same as the C function OGR_G_IsRing().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always return FALSE.

virtual 
Test if the geometry is simple.
This method is the same as the C function OGR_G_IsSimple().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always return FALSE.

virtual 
Test if the geometry is valid.
This method is the same as the C function OGR_G_IsValid().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always return FALSE.
Reimplemented in OGRCircularString.

virtual 
Attempts to make an invalid geometry valid without losing vertices.
Alreadyvalid geometries are cloned without further intervention.
Running OGRGeometryFactory::removeLowerDimensionSubGeoms() as a postprocessing step is often desired.
This method is the same as the C function OGR_G_MakeValid().
This function is built on the GEOS >= 3.8 library, check it for the definition of the geometry operation. If OGR is built without the GEOS >= 3.8 library, this function will return a clone of the input geometry if it is valid, or NULL if it is invalid
papszOptions  NULL terminated list of options, or NULL. The following options are available:


virtual 
Attempts to bring geometry into normalized/canonical form.
This method is the same as the C function OGR_G_Normalize().
This function is built on the GEOS library; check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.
OGRGeometry & OGRGeometry::operator=  (  const OGRGeometry &  other  ) 
Assignment operator.
Note: before GDAL 2.1, only the default implementation of the operator existed, which could be unsafe to use.

virtual 
Test for overlap.
Tests if this geometry and the other passed into the method overlap, that is their intersection has a nonzero area.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_Overlaps().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the geometry to compare to this geometry. 

virtual 
Polygonizes a set of sparse edges.
A new geometry object is created and returned containing a collection of reassembled Polygons: NULL will be returned if the input collection doesn't corresponds to a MultiLinestring, or when reassembling Edges into Polygons is impossible due to topological inconsistencies.
This method is the same as the C function OGR_G_Polygonize().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.

virtual 
Modify the geometry such it has no segment longer then the given distance.
This method modifies the geometry to add intermediate vertices if necessary so that the maximum length between 2 consecutive vertices is lower than dfMaxLength.
Interpolated points will have Z and M values (if needed) set to 0. Distance computation is performed in 2d only
This function is the same as the C function OGR_G_Segmentize()
dfMaxLength  the maximum distance between 2 points after segmentization 
Reimplemented in OGRSimpleCurve, OGRCircularString, OGRCompoundCurve, OGRCurvePolygon, and OGRGeometryCollection.

virtual 
Add or remove the Z coordinate dimension.
This method adds or removes the explicit Z coordinate dimension. Removing the Z coordinate dimension of a geometry will remove any existing Z values. Adding the Z dimension to a geometry collection, a compound curve, a polygon, etc. will affect the children geometries.
bIs3D  Should the geometry have a Z dimension, either TRUE or FALSE. 
Reimplemented in OGRSimpleCurve, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

virtual 
Set the coordinate dimension.
This method sets the explicit coordinate dimension. Setting the coordinate dimension of a geometry to 2 should zero out any existing Z values. Setting the dimension of a geometry collection, a compound curve, a polygon, etc. will affect the children geometries. This will also remove the M dimension if present before this call.
nNewDimension  New coordinate dimension value, either 2 or 3. 
Reimplemented in OGRPoint, OGRSimpleCurve, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

virtual 
Add or remove the M coordinate dimension.
This method adds or removes the explicit M coordinate dimension. Removing the M coordinate dimension of a geometry will remove any existing M values. Adding the M dimension to a geometry collection, a compound curve, a polygon, etc. will affect the children geometries.
bIsMeasured  Should the geometry have a M dimension, either TRUE or FALSE. 
Reimplemented in OGRSimpleCurve, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

virtual 
Simplify the geometry.
This function is the same as the C function OGR_G_Simplify().
This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.
dTolerance  the distance tolerance for the simplification. 
OGRGeometry * OGRGeometry::SimplifyPreserveTopology  (  double  dTolerance  )  const 
Simplify the geometry while preserving topology.
This function is the same as the C function OGR_G_SimplifyPreserveTopology().
This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.
dTolerance  the distance tolerance for the simplification. 

virtual 
Swap x and y coordinates.
Reimplemented in OGRPoint, OGRSimpleCurve, OGRCompoundCurve, OGRCurvePolygon, OGRGeometryCollection, and OGRPolyhedralSurface.

virtual 
Compute symmetric difference.
Generates a new geometry which is the symmetric difference of this geometry and the second geometry passed into the method.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_SymDifference().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the other geometry. 

inline 
Downcast to OGRCircularString*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbCircularString.

inline 
Downcast to OGRCircularString*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbCircularString.

inline 
Downcast to OGRCompoundCurve*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbCompoundCurve.

inline 
Downcast to OGRCompoundCurve*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbCompoundCurve.

inline 
Downcast to OGRCurve*.
Implies prior checking that OGR_GT_IsSubClass(getGeometryType(), wkbCurve).

inline 
Downcast to OGRCurve*.
Implies prior checking that OGR_GT_IsSubClass(getGeometryType(), wkbCurve).

inline 
Downcast to OGRCurvePolygon*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbCurvePolygon or wkbPolygon or wkbTriangle.

inline 
Downcast to OGRCurvePolygon*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbCurvePolygon or wkbPolygon or wkbTriangle.

inline 
Downcast to OGRGeometryCollection*.
Implies prior checking that OGR_GT_IsSubClass(getGeometryType(), wkbGeometryCollection).

inline 
Downcast to OGRGeometryCollection*.
Implies prior checking that OGR_GT_IsSubClass(getGeometryType(), wkbGeometryCollection).

inlinestatic 
Convert a OGRGeometry* to a OGRGeometryH.

inline 
Downcast to OGRLinearRing*.
Implies prior checking that EQUAL(getGeometryName(), "LINEARRING").

inline 
Downcast to OGRLinearRing*.
Implies prior checking that EQUAL(getGeometryName(), "LINEARRING").

inline 
Downcast to OGRLineString*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbLineString.

inline 
Downcast to OGRLineString*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbLineString.

inline 
Downcast to OGRMultiCurve*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiCurve and derived types.

inline 
Downcast to OGRMultiCurve*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiCurve and derived types.

inline 
Downcast to OGRMultiLineString*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiLineString.

inline 
Downcast to OGRMultiLineString*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiLineString.

inline 
Downcast to OGRMultiPoint*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiPoint.

inline 
Downcast to OGRMultiPoint*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiPoint.

inline 
Downcast to OGRMultiPolygon*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiPolygon.

inline 
Downcast to OGRMultiPolygon*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiPolygon.

inline 
Downcast to OGRMultiSurface*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiSurface and derived types.

inline 
Downcast to OGRMultiSurface*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbMultiSurface and derived types.

inline 
Downcast to OGRPoint*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbPoint.

inline 
Downcast to OGRPoint*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbPoint.

inline 
Downcast to OGRPolygon*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbPolygon or wkbTriangle.

inline 
Downcast to OGRPolygon*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbPolygon or wkbTriangle.

inline 
Downcast to OGRPolyhedralSurface*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbPolyhedralSurface or wkbTIN.

inline 
Downcast to OGRPolyhedralSurface*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbPolyhedralSurface or wkbTIN.

inline 
Downcast to OGRSimpleCurve*.
Implies prior checking that getGeometryType() is wkbLineString, wkbCircularString or a derived type.

inline 
Downcast to OGRSimpleCurve*.
Implies prior checking that getGeometryType() is wkbLineString, wkbCircularString or a derived type.

inline 
Downcast to OGRSurface*.
Implies prior checking that OGR_GT_IsSubClass(getGeometryType(), wkbSurface).

inline 
Downcast to OGRSurface*.
Implies prior checking that OGR_GT_IsSubClass(getGeometryType(), wkbSurface).

inline 
Downcast to OGRTriangle*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbTriangle.

inline 
Downcast to OGRTriangle*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbTriangle.

inline 
Downcast to OGRTriangulatedSurface*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbTIN.

inline 
Downcast to OGRTriangulatedSurface*.
Implies prior checking that wkbFlatten(getGeometryType()) == wkbTIN.

virtual 
Test for touching.
Tests if this geometry and the other passed into the method are touching.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_Touches().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the geometry to compare to this geometry. 

pure virtual 
Apply arbitrary coordinate transformation to geometry.
This method will transform the coordinates of a geometry from their current spatial reference system to a new target spatial reference system. Normally this means reprojecting the vectors, but it could include datum shifts, and changes of units.
Note that this method does not require that the geometry already have a spatial reference system. It will be assumed that they can be treated as having the source spatial reference system of the OGRCoordinateTransformation object, and the actual SRS of the geometry will be ignored. On successful completion the output OGRSpatialReference of the OGRCoordinateTransformation will be assigned to the geometry.
This method is the same as the C function OGR_G_Transform().
poCT  the transformation to apply. 
Implemented in OGRPolyhedralSurface, OGRPoint, OGRSimpleCurve, OGRLinearRing, OGRCompoundCurve, OGRCurvePolygon, and OGRGeometryCollection.
OGRErr OGRGeometry::transformTo  (  OGRSpatialReference *  poSR  ) 
Transform geometry to new spatial reference system.
This method will transform the coordinates of a geometry from their current spatial reference system to a new target spatial reference system. Normally this means reprojecting the vectors, but it could include datum shifts, and changes of units.
This method will only work if the geometry already has an assigned spatial reference system, and if it is transformable to the target coordinate system.
Because this method requires internal creation and initialization of an OGRCoordinateTransformation object it is significantly more expensive to use this method to transform many geometries than it is to create the OGRCoordinateTransformation in advance, and call transform() with that transformation. This method exists primarily for convenience when only transforming a single geometry.
This method is the same as the C function OGR_G_TransformTo().
poSR  spatial reference system to transform to. 

virtual 
Compute union.
Generates a new geometry which is the region of union of the two geometries operated on.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_Union().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the other geometry unioned with "this" geometry. 

virtual 
Compute union using cascading.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_UnionCascaded().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.

virtual 
Test for containment.
Tests if actual geometry object is within the passed geometry.
Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.
This method is the same as the C function OGR_G_Within().
This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.
poOtherGeom  the geometry to compare to this geometry. 
Reimplemented in OGRPoint.

pure virtual 
Returns size of related binary representation.
This method returns the exact number of bytes required to hold the well known binary representation of this geometry object. Its computation may be slightly expensive for complex geometries.
This method relates to the SFCOM IWks::WkbSize() method.
This method is the same as the C function OGR_G_WkbSize().
Implemented in OGRPoint, OGRSimpleCurve, OGRCompoundCurve, OGRCurvePolygon, OGRPolygon, OGRGeometryCollection, and OGRPolyhedralSurface.