GDAL
Public Member Functions | Static Public Member Functions | List of all members
OGRGeometry Class Referenceabstract

Abstract base class for all geometry classes. More...

#include <ogr_geometry.h>

Inheritance diagram for OGRGeometry:
OGRCurve OGRGeometryCollection OGRPoint OGRSurface OGRCompoundCurve OGRSimpleCurve OGRMultiCurve OGRMultiPoint OGRMultiSurface OGRCurvePolygon OGRCircularString OGRLineString OGRMultiLineString OGRMultiPolygon OGRPolygon OGRLinearRing

Public Member Functions

 OGRGeometry (const OGRGeometry &other)
 Copy constructor. More...
 
OGRGeometryoperator= (const OGRGeometry &other)
 Assignment operator. More...
 
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
 Returns TRUE (non-zero) if the object has no points. More...
 
virtual OGRBoolean IsValid () const
 Test if the geometry is valid. 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 OGRGeometryclone () const CPL_WARN_UNUSED_RESULT=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 int WkbSize () const =0
 Returns size of related binary representation. More...
 
virtual OGRErr importFromWkb (unsigned char *, int=-1, OGRwkbVariant=wkbVariantOldOgc)=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 (char **ppszInput)=0
 Assign geometry from well known text data. More...
 
virtual OGRErr exportToWkt (char **ppszDstText, OGRwkbVariant=wkbVariantOldOgc) const =0
 Convert a geometry into well known text format. 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...
 
virtual void dumpReadable (FILE *, const char *=NULL, char **papszOptions=NULL) 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=NULL) 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 GEOSGeom exportToGEOS (GEOSContextHandle_t hGEOSCtxt) const CPL_WARN_UNUSED_RESULT
 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 OGRGeometrygetCurveGeometry (const char *const *papszOptions=NULL) const CPL_WARN_UNUSED_RESULT
 Return curve version of this geometry. More...
 
virtual OGRGeometrygetLinearGeometry (double dfMaxAngleStepSizeDegrees=0, const char *const *papszOptions=NULL) const CPL_WARN_UNUSED_RESULT
 Return, possibly approximate, non-curve 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...
 
void assignSpatialReference (OGRSpatialReference *poSR)
 Assign spatial reference to this object. More...
 
OGRSpatialReferencegetSpatialReference (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 (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 OGRGeometryBoundary () const CPL_WARN_UNUSED_RESULT
 Compute boundary. More...
 
virtual double Distance (const OGRGeometry *) const
 Compute distance between two geometries. More...
 
virtual OGRGeometryConvexHull () const CPL_WARN_UNUSED_RESULT
 Compute convex hull. More...
 
virtual OGRGeometryBuffer (double dfDist, int nQuadSegs=30) const CPL_WARN_UNUSED_RESULT
 Compute buffer of geometry. More...
 
virtual OGRGeometryIntersection (const OGRGeometry *) const CPL_WARN_UNUSED_RESULT
 Compute intersection. More...
 
virtual OGRGeometryUnion (const OGRGeometry *) const CPL_WARN_UNUSED_RESULT
 Compute union. More...
 
virtual OGRGeometryUnionCascaded () const CPL_WARN_UNUSED_RESULT
 Compute union using cascading. More...
 
virtual OGRGeometryDifference (const OGRGeometry *) const CPL_WARN_UNUSED_RESULT
 Compute difference. More...
 
virtual OGRGeometrySymDifference (const OGRGeometry *) const CPL_WARN_UNUSED_RESULT
 Compute symmetric difference. More...
 
virtual OGRErr Centroid (OGRPoint *poPoint) const
 Compute the geometry centroid. More...
 
virtual OGRGeometrySimplify (double dTolerance) const CPL_WARN_UNUSED_RESULT
 Simplify the geometry. More...
 
OGRGeometrySimplifyPreserveTopology (double dTolerance) const CPL_WARN_UNUSED_RESULT
 Simplify the geometry while preserving topology. More...
 
virtual OGRGeometryDelaunayTriangulation (double dfTolerance, int bOnlyEdges) const CPL_WARN_UNUSED_RESULT
 Return a Delaunay triangulation of the vertices of the geometry. More...
 
virtual OGRGeometryPolygonize () const CPL_WARN_UNUSED_RESULT
 Polygonizes a set of sparse edges. More...
 
virtual void swapXY ()
 Swap x and y coordinates. 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...
 

Detailed Description

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 "OpenGISĀ® Implementation Specification for Geographic information - Simple feature access - Part 1: Common architecture" (OGC 06-103r4)

In GDAL 2.0, the hierarchy of classes has been extended with (working draft) ISO SQL/MM Part 3 (ISO/IEC 13249-3) curve geometries : CIRCULARSTRING (OGRCircularString), COMPOUNDCURVE (OGRCompoundCurve), CURVEPOLYGON (OGRCurvePolygon), MULTICURVE (OGRMultiCurve) and MULTISURFACE (OGRMultiSurface).

Constructor & Destructor Documentation

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.

Since
GDAL 2.1

Member Function Documentation

void OGRGeometry::assignSpatialReference ( OGRSpatialReference poSR)

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.

This is similar to the SFCOM IGeometry::put_SpatialReference() method.

This method is the same as the C function OGR_G_AssignSpatialReference().

Parameters
poSRnew spatial reference system to apply.
OGRGeometry * OGRGeometry::Boundary ( ) const
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.

Returns
a newly allocated geometry now owned by the caller, or NULL on failure.
Since
OGR 1.8.0
OGRGeometry * OGRGeometry::Buffer ( double  dfDist,
int  nQuadSegs = 30 
) const
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.

Parameters
dfDistthe buffer distance to be applied. Should be expressed into the same unit as the coordinates of the geometry.
nQuadSegsthe number of segments used to approximate a 90 degree (quadrant) of curvature.
Returns
the newly created geometry, or NULL if an error occurs.
OGRErr OGRGeometry::Centroid ( OGRPoint poPoint) const
virtual

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/MM-Part 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.

Returns
OGRERR_NONE on success or OGRERR_FAILURE on error.
Since
OGR 1.8.0 as a OGRGeometry method (previously was restricted to OGRPolygon)
OGRGeometry * OGRGeometry::clone ( ) const
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().

Returns
a new object instance with the same geometry, and spatial reference system as the original.

Implemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRLinearRing, OGRSimpleCurve, and OGRPoint.

void OGRGeometry::closeRings ( )
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 OGRGeometryCollection, OGRPolygon, and OGRLinearRing.

OGRBoolean OGRGeometry::Contains ( const OGRGeometry poOtherGeom) const
virtual

Test for containment.

Tests if actual geometry object contains the passed geometry.

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.

Parameters
poOtherGeomthe geometry to compare to this geometry.
Returns
TRUE if poOtherGeom contains this geometry, otherwise FALSE.

Reimplemented in OGRCurvePolygon.

OGRGeometry * OGRGeometry::ConvexHull ( ) const
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.

Returns
a newly allocated geometry now owned by the caller, or NULL on failure.
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().

Returns
this will return 2 for XY, 3 for XYZ and XYM, and 4 for XYZM data.
Since
GDAL 2.1
GEOSContextHandle_t OGRGeometry::createGEOSContext ( )
static

Create a new GEOS context.

Returns
a new GEOS context.
OGRBoolean OGRGeometry::Crosses ( const OGRGeometry poOtherGeom) const
virtual

Test for crossing.

Tests if this geometry and the other passed into the method are crossing.

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.

Parameters
poOtherGeomthe geometry to compare to this geometry.
Returns
TRUE if they are crossing, otherwise FALSE.
OGRGeometry * OGRGeometry::DelaunayTriangulation ( double  dfTolerance,
int  bOnlyEdges 
) const
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.

Parameters
dfToleranceoptional snapping tolerance to use for improved robustness
bOnlyEdgesif TRUE, will return a MULTILINESTRING, otherwise it will return a GEOMETRYCOLLECTION containing triangular POLYGONs.
Returns
the geometry resulting from the Delaunay triangulation or NULL if an error occurs.
Since
OGR 2.1
OGRGeometry * OGRGeometry::Difference ( const OGRGeometry poOtherGeom) const
virtual

Compute difference.

Generates a new geometry which is the region of this geometry with the region of the second geometry removed.

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.

Parameters
poOtherGeomthe other geometry removed from "this" geometry.
Returns
a new geometry representing the difference or NULL if the difference is empty or an error occurs.
OGRBoolean OGRGeometry::Disjoint ( const OGRGeometry poOtherGeom) const
virtual

Test for disjointness.

Tests if this geometry and the other passed into the method are disjoint.

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.

Parameters
poOtherGeomthe geometry to compare to this geometry.
Returns
TRUE if they are disjoint, otherwise FALSE.
double OGRGeometry::Distance ( const OGRGeometry poOtherGeom) const
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.

Parameters
poOtherGeomthe other geometry to compare against.
Returns
the distance between the geometries or -1 if an error occurs.
void OGRGeometry::dumpReadable ( FILE *  fp,
const char *  pszPrefix = NULL,
char **  papszOptions = NULL 
) const
virtual

Dump geometry in well known text format to indicated output file.

A few options can be defined to change the default dump :

  • DISPLAY_GEOMETRY=NO : to hide the dump of the geometry
  • DISPLAY_GEOMETRY=WKT or YES (default) : dump the geometry as a WKT
  • DISPLAY_GEOMETRY=SUMMARY : to get only a summary of the geometry

This method is the same as the C function OGR_G_DumpReadable().

Parameters
fpthe text file to write the geometry to.
pszPrefixthe prefix to put on each line of output.
papszOptionsNULL terminated list of options (may be NULL)
void OGRGeometry::empty ( )
pure virtual

Clear geometry information.

This restores the geometry to it's 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 OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRSimpleCurve, and OGRPoint.

int OGRGeometry::Equals ( OGRGeometry poOtherGeom) const
pure virtual

Returns TRUE if two geometries are equivalent.

This method is the same as the C function OGR_G_Equals().

Returns
TRUE if equivalent or FALSE otherwise.

Implemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRSimpleCurve, and OGRPoint.

GEOSGeom OGRGeometry::exportToGEOS ( GEOSContextHandle_t  hGEOSCtxt) const
virtual

Returns a GEOSGeom object corresponding to the geometry.

Parameters
hGEOSCtxtGEOS context
Returns
a GEOSGeom object corresponding to the geometry.
char * OGRGeometry::exportToGML ( const char *const *  papszOptions = NULL) const
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 :

  • FORMAT=GML3. Otherwise it will default to GML 2.1.2 output.
  • GML3_LINESTRING_ELEMENT=curve. (Only valid for FORMAT=GML3) To use gml:Curve element for linestrings. Otherwise gml:LineString will be used .
  • GML3_LONGSRS=YES/NO. (Only valid for FORMAT=GML3) Default to YES. If YES, SRS with EPSG authority will be written with the "urn:ogc:def:crs:EPSG::" prefix. In the case, if the SRS is a geographic SRS without explicit AXIS order, but that the same SRS authority code imported with ImportFromEPSGA() should be treated as lat/long, then the function will take care of coordinate order swapping. If set to NO, SRS with EPSG authority will be written with the "EPSG:" prefix, even if they are in lat/long order.

This method is the same as the C function OGR_G_ExportToGMLEx().

Parameters
papszOptionsNULL-terminated list of options.
Returns
A GML fragment or NULL in case of error.
char * OGRGeometry::exportToJson ( ) const
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().

Returns
A GeoJSON fragment or NULL in case of error.
char * OGRGeometry::exportToKML ( ) const
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().

Returns
A KML fragment or NULL in case of error.
OGRErr OGRGeometry::exportToWkb ( OGRwkbByteOrder  eByteOrder,
unsigned char *  pabyData,
OGRwkbVariant  eWkbVariant = wkbVariantOldOgc 
) const
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.

Parameters
eByteOrderOne of wkbXDR or wkbNDR indicating MSB or LSB byte order respectively.
pabyDataa buffer into which the binary representation is written. This buffer must be at least OGRGeometry::WkbSize() byte in size.
eWkbVariantWhat 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.
Returns
Currently OGRERR_NONE is always returned.

Implemented in OGRGeometryCollection, OGRPolygon, OGRCurvePolygon, OGRCompoundCurve, OGRCircularString, OGRLinearRing, OGRSimpleCurve, and OGRPoint.

OGRErr OGRGeometry::exportToWkt ( char **  ppszDstText,
OGRwkbVariant  eWkbVariant = wkbVariantOldOgc 
) const
pure virtual

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().

Parameters
ppszDstTexta text buffer is allocated by the program, and assigned to the passed pointer. After use, *ppszDstText should be freed with OGRFree().
eWkbVariantthe specification that must be conformed too :
  • wbkVariantOgc for old-style 99-402 extended dimension (Z) WKB types
  • wbkVariantIso for SFSQL 1.2 and ISO SQL/MM Part 3
Returns
Currently OGRERR_NONE is always returned.

Implemented in OGRMultiLineString, OGRMultiCurve, OGRMultiPoint, OGRMultiPolygon, OGRMultiSurface, OGRGeometryCollection, OGRPolygon, OGRCurvePolygon, OGRCompoundCurve, OGRCircularString, OGRSimpleCurve, and OGRPoint.

void OGRGeometry::flattenTo2D ( )
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 OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRSimpleCurve, and OGRPoint.

void OGRGeometry::freeGEOSContext ( GEOSContextHandle_t  hGEOSCtxt)
static

Destroy a GEOS context.

Parameters
hGEOSCtxtGEOS context
int OGRGeometry::getCoordinateDimension ( ) const
virtual

Get the dimension of the coordinates in this object.

This method is the same as the C function OGR_G_GetCoordinateDimension().

Deprecated:
use CoordinateDimension().
Returns
this will return 2 or 3.
OGRGeometry * OGRGeometry::getCurveGeometry ( const char *const *  papszOptions = NULL) const
virtual

Return curve version of this geometry.

Returns a geometry that has possibly CIRCULARSTRING, COMPOUNDCURVE, CURVEPOLYGON, MULTICURVE or MULTISURFACE in it, by de-approximating 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().

Parameters
papszOptionsoptions as a null-terminated list of strings. Unused for now. Must be set to NULL.
Returns
a new geometry.
Since
GDAL 2.0

Reimplemented in OGRGeometryCollection, OGRPolygon, and OGRLineString.

int OGRGeometry::getDimension ( ) const
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().

Returns
0 for points, 1 for lines and 2 for surfaces.

Implemented in OGRMultiCurve, OGRMultiPoint, OGRMultiSurface, OGRGeometryCollection, OGRCurvePolygon, OGRCurve, and OGRPoint.

void OGRGeometry::getEnvelope ( OGREnvelope *  psEnvelope) const
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().

Parameters
psEnvelopethe structure in which to place the results.

Implemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRCircularString, OGRSimpleCurve, and OGRPoint.

void OGRGeometry::getEnvelope ( OGREnvelope3D *  psEnvelope) const
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().

Parameters
psEnvelopethe structure in which to place the results.
Since
OGR 1.9.0

Implemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRCircularString, OGRSimpleCurve, and OGRPoint.

const char * OGRGeometry::getGeometryName ( ) const
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().

Returns
name used for this geometry type in well known text format. The returned pointer is to a static internal string and should not be modified or freed.

Implemented in OGRMultiLineString, OGRMultiCurve, OGRMultiPoint, OGRMultiPolygon, OGRMultiSurface, OGRGeometryCollection, OGRPolygon, OGRCurvePolygon, OGRCompoundCurve, OGRCircularString, OGRLinearRing, OGRLineString, and OGRPoint.

OGRwkbGeometryType OGRGeometry::getGeometryType ( ) const
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().

Returns
the geometry type code.

Implemented in OGRMultiLineString, OGRMultiCurve, OGRMultiPoint, OGRMultiPolygon, OGRMultiSurface, OGRGeometryCollection, OGRPolygon, OGRCurvePolygon, OGRCompoundCurve, OGRCircularString, OGRLineString, and OGRPoint.

OGRwkbGeometryType OGRGeometry::getIsoGeometryType ( ) const

Get the geometry type that conforms with ISO SQL/MM Part3.

Returns
the geometry type that conforms with ISO SQL/MM Part3
OGRGeometry * OGRGeometry::getLinearGeometry ( double  dfMaxAngleStepSizeDegrees = 0,
const char *const *  papszOptions = NULL 
) const
virtual

Return, possibly approximate, non-curve 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().

Parameters
dfMaxAngleStepSizeDegreesthe largest step in degrees along the arc, zero to use the default setting.
papszOptionsoptions as a null-terminated list of strings. See OGRGeometryFactory::curveToLineString() for valid options.
Returns
a new geometry.
Since
GDAL 2.0

Reimplemented in OGRGeometryCollection, OGRPolygon, OGRCurvePolygon, OGRCompoundCurve, and OGRCircularString.

OGRSpatialReference * OGRGeometry::getSpatialReference ( void  ) const
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().

Returns
a reference to the spatial reference object. The object may be shared with many geometry objects, and should not be modified.
OGRBoolean OGRGeometry::hasCurveGeometry ( int  bLookForNonLinear = FALSE) const
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 non-linear 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 "loss-less" conversion.

This method is the same as the C function OGR_G_HasCurveGeometry().

Parameters
bLookForNonLinearset it to TRUE to check if the geometry is or contains a CIRCULARSTRING.
Returns
TRUE if this geometry is or has curve geometry.
Since
GDAL 2.0

Reimplemented in OGRMultiLineString, OGRMultiCurve, OGRMultiPoint, OGRMultiPolygon, OGRMultiSurface, OGRGeometryCollection, OGRPolygon, OGRCurvePolygon, OGRCompoundCurve, and OGRCircularString.

OGRErr OGRGeometry::importFromWkb ( unsigned char *  pabyData,
int  nSize = -1,
OGRwkbVariant  eWkbVariant = wkbVariantOldOgc 
)
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().

Parameters
pabyDatathe binary input data.
nSizethe size of pabyData in bytes, or zero if not known.
eWkbVariantif wkbVariantPostGIS1, special interpretation is done for curve geometries code
Returns
OGRERR_NONE if all goes well, otherwise any of OGRERR_NOT_ENOUGH_DATA, OGRERR_UNSUPPORTED_GEOMETRY_TYPE, or OGRERR_CORRUPT_DATA may be returned.

Implemented in OGRGeometryCollection, OGRPolygon, OGRCurvePolygon, OGRCompoundCurve, OGRCircularString, OGRLinearRing, OGRSimpleCurve, and OGRPoint.

OGRErr OGRGeometry::importFromWkt ( char **  ppszInput)
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().

Parameters
ppszInputpointer to a pointer to the source text. The pointer is updated to pointer after the consumed text.
Returns
OGRERR_NONE if all goes well, otherwise any of OGRERR_NOT_ENOUGH_DATA, OGRERR_UNSUPPORTED_GEOMETRY_TYPE, or OGRERR_CORRUPT_DATA may be returned.

Implemented in OGRMultiCurve, OGRMultiPoint, OGRMultiSurface, OGRGeometryCollection, OGRPolygon, OGRCurvePolygon, OGRCompoundCurve, OGRCircularString, OGRSimpleCurve, and OGRPoint.

OGRGeometry * OGRGeometry::Intersection ( const OGRGeometry poOtherGeom) const
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.

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.

Parameters
poOtherGeomthe other geometry intersected with "this" geometry.
Returns
a new geometry representing the intersection or NULL if there is no intersection or an error occurs.
OGRBoolean OGRGeometry::Intersects ( const OGRGeometry poOtherGeom) const
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().

Parameters
poOtherGeomthe other geometry to test against.
Returns
TRUE if the geometries intersect, otherwise FALSE.

Reimplemented in OGRCurvePolygon, and OGRPoint.

OGRBoolean OGRGeometry::Is3D ( ) const
inline

Returns whether the geometry has a Z component.

OGRBoolean OGRGeometry::IsEmpty ( ) const
virtual

Returns TRUE (non-zero) 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.

Returns
TRUE if object is empty, otherwise FALSE.

Reimplemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRSimpleCurve, and OGRPoint.

OGRBoolean OGRGeometry::IsMeasured ( ) const
inline

Returns whether the geometry has a M component.

OGRBoolean OGRGeometry::IsRing ( ) const
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.

Returns
TRUE if the geometry has no points, otherwise FALSE.
OGRBoolean OGRGeometry::IsSimple ( ) const
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.

Returns
TRUE if the geometry has no points, otherwise FALSE.
OGRBoolean OGRGeometry::IsValid ( ) const
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.

Returns
TRUE if the geometry has no points, otherwise FALSE.

Reimplemented in OGRCircularString.

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.

Since
GDAL 2.1
OGRBoolean OGRGeometry::Overlaps ( const OGRGeometry poOtherGeom) const
virtual

Test for overlap.

Tests if this geometry and the other passed into the method overlap, that is their intersection has a non-zero area.

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.

Parameters
poOtherGeomthe geometry to compare to this geometry.
Returns
TRUE if they are overlapping, otherwise FALSE.
OGRGeometry * OGRGeometry::Polygonize ( ) const
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.

Returns
a newly allocated geometry now owned by the caller, or NULL on failure.
Since
OGR 1.9.0
void OGRGeometry::segmentize ( double  dfMaxLength)
virtual

Modify the geometry such it has no segment longer then the given distance.

Add intermediate vertices to a geometry.

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()

Parameters
dfMaxLengththe maximum distance between 2 points after segmentization

This method modifies the geometry to add intermediate vertices if necessary so that the maximum length between 2 consecutive vertices is lower than dfMaxLength.

Parameters
dfMaxLengthmaximum length between 2 consecutive vertices.

Reimplemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRCircularString, and OGRSimpleCurve.

void OGRGeometry::set3D ( OGRBoolean  bIs3D)
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.

Parameters
bIs3DShould the geometry have a Z dimension, either TRUE or FALSE.
Since
GDAL 2.1

Reimplemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, and OGRSimpleCurve.

void OGRGeometry::setCoordinateDimension ( int  nNewDimension)
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.

Deprecated:
use set3D() or setMeasured().
Parameters
nNewDimensionNew coordinate dimension value, either 2 or 3.

Reimplemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRSimpleCurve, and OGRPoint.

void OGRGeometry::setMeasured ( OGRBoolean  bIsMeasured)
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.

Parameters
bIsMeasuredShould the geometry have a M dimension, either TRUE or FALSE.
Since
GDAL 2.1

Reimplemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, and OGRSimpleCurve.

OGRGeometry * OGRGeometry::Simplify ( double  dTolerance) const
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.

Parameters
dTolerancethe distance tolerance for the simplification.
Returns
the simplified geometry or NULL if an error occurs.
Since
OGR 1.8.0
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.

Parameters
dTolerancethe distance tolerance for the simplification.
Returns
the simplified geometry or NULL if an error occurs.
Since
OGR 1.9.0
void OGRGeometry::swapXY ( )
virtual

Swap x and y coordinates.

Since
OGR 1.8.0

Reimplemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRSimpleCurve, and OGRPoint.

OGRGeometry * OGRGeometry::SymDifference ( const OGRGeometry poOtherGeom) const
virtual

Compute symmetric difference.

Generates a new geometry which is the symmetric difference of this geometry and the second geometry passed into the method.

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.

Parameters
poOtherGeomthe other geometry.
Returns
a new geometry representing the symmetric difference or NULL if the difference is empty or an error occurs.
Since
OGR 1.8.0
OGRBoolean OGRGeometry::Touches ( const OGRGeometry poOtherGeom) const
virtual

Test for touching.

Tests if this geometry and the other passed into the method are touching.

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.

Parameters
poOtherGeomthe geometry to compare to this geometry.
Returns
TRUE if they are touching, otherwise FALSE.
OGRErr OGRGeometry::transform ( OGRCoordinateTransformation poCT)
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().

Parameters
poCTthe transformation to apply.
Returns
OGRERR_NONE on success or an error code.

Implemented in OGRGeometryCollection, OGRCurvePolygon, OGRCompoundCurve, OGRSimpleCurve, and OGRPoint.

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().

Parameters
poSRspatial reference system to transform to.
Returns
OGRERR_NONE on success, or an error code.
OGRGeometry * OGRGeometry::Union ( const OGRGeometry poOtherGeom) const
virtual

Compute union.

Generates a new geometry which is the region of union of the two geometries operated on.

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.

Parameters
poOtherGeomthe other geometry unioned with "this" geometry.
Returns
a new geometry representing the union or NULL if an error occurs.
OGRGeometry * OGRGeometry::UnionCascaded ( ) const
virtual

Compute union using cascading.

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.

Returns
a new geometry representing the union or NULL if an error occurs.
Since
OGR 1.8.0
OGRBoolean OGRGeometry::Within ( const OGRGeometry poOtherGeom) const
virtual

Test for containment.

Tests if actual geometry object is within the passed geometry.

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.

Parameters
poOtherGeomthe geometry to compare to this geometry.
Returns
TRUE if poOtherGeom is within this geometry, otherwise FALSE.

Reimplemented in OGRPoint.

int OGRGeometry::WkbSize ( ) const
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().

Returns
size of binary representation in bytes.

Implemented in OGRGeometryCollection, OGRPolygon, OGRCurvePolygon, OGRCompoundCurve, OGRLinearRing, OGRSimpleCurve, and OGRPoint.


The documentation for this class was generated from the following files:

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