OGRGeometryFactory Class Reference

Create geometry objects from well known text/binary. More...

#include <ogr_geometry.h>

Classes
class	TransformWithOptionsCache
	Opaque class used as argument to transformWithOptions() More...

Static Public Member Functions
static OGRErr	createFromWkb (const void *, const OGRSpatialReference *, OGRGeometry **, size_t=static_cast< size_t >(-1), OGRwkbVariant=wkbVariantOldOgc)
	Create a geometry object of the appropriate type from its well known binary representation. More...
static OGRErr	createFromWkb (const void *pabyData, const OGRSpatialReference *, OGRGeometry **, size_t nSize, OGRwkbVariant eVariant, size_t &nBytesConsumedOut)
	Create a geometry object of the appropriate type from its well known binary representation. More...
static OGRErr	createFromWkt (const char *, const OGRSpatialReference *, OGRGeometry **)
	Create a geometry object of the appropriate type from its well known text representation. More...
static OGRErr	createFromWkt (const char **, const OGRSpatialReference *, OGRGeometry **)
	Create a geometry object of the appropriate type from its well known text representation. More...
static OGRErr	createFromWkt (char **ppszInput, const OGRSpatialReference *poSRS, OGRGeometry **ppoGeom)
	Deprecated. More...
static OGRErr	createFromFgf (const void *, OGRSpatialReference *, OGRGeometry **, int=-1, int *=nullptr)
	Create a geometry object of the appropriate type from its FGF (FDO Geometry Format) binary representation. More...
static OGRGeometry *	createFromGML (const char *)
	Create geometry from GML. More...
static OGRGeometry *	createFromGEOS (GEOSContextHandle_t hGEOSCtxt, GEOSGeom)
	Builds a OGRGeometry* from a GEOSGeom. More...
static OGRGeometry *	createFromGeoJson (const char *, int=-1)
	Create geometry from GeoJson fragment. More...
static OGRGeometry *	createFromGeoJson (const CPLJSONObject &oJSONObject)
	Create geometry from GeoJson fragment. More...
static void	destroyGeometry (OGRGeometry *)
	Destroy geometry object. More...
static OGRGeometry *	createGeometry (OGRwkbGeometryType)
	Create an empty geometry of desired type. More...
static OGRGeometry *	forceToPolygon (OGRGeometry *)
	Convert to polygon. More...
static OGRGeometry *	forceToLineString (OGRGeometry *, bool bOnlyInOrder=true)
	Convert to line string. More...
static OGRGeometry *	forceToMultiPolygon (OGRGeometry *)
	Convert to multipolygon. More...
static OGRGeometry *	forceToMultiPoint (OGRGeometry *)
	Convert to multipoint. More...
static OGRGeometry *	forceToMultiLineString (OGRGeometry *)
	Convert to multilinestring. More...
static OGRGeometry *	forceTo (OGRGeometry *poGeom, OGRwkbGeometryType eTargetType, const char *const *papszOptions=nullptr)
	Convert to another geometry type. More...
static OGRGeometry *	removeLowerDimensionSubGeoms (const OGRGeometry *poGeom)
	Remove sub-geometries from a geometry collection that do not have the maximum topological dimensionality of the collection. More...
static OGRGeometry *	organizePolygons (OGRGeometry **papoPolygons, int nPolygonCount, int *pbResultValidGeometry, const char **papszOptions=nullptr)
	Organize polygons based on geometries. More...
static bool	haveGEOS ()
	Test if GEOS enabled. More...
static OGRGeometry *	transformWithOptions (const OGRGeometry *poSrcGeom, OGRCoordinateTransformation *poCT, char **papszOptions, const TransformWithOptionsCache &cache=TransformWithOptionsCache())
	Transform a geometry. More...
static OGRGeometry *	approximateArcAngles (double dfX, double dfY, double dfZ, double dfPrimaryRadius, double dfSecondaryAxis, double dfRotation, double dfStartAngle, double dfEndAngle, double dfMaxAngleStepSizeDegrees, const bool bUseMaxGap=false)
	Stroke arc to linestring. More...
static int	GetCurveParameters (double x0, double y0, double x1, double y1, double x2, double y2, double &R, double &cx, double &cy, double &alpha0, double &alpha1, double &alpha2)
	Returns the parameter of an arc circle. More...
static OGRLineString *	curveToLineString (double x0, double y0, double z0, double x1, double y1, double z1, double x2, double y2, double z2, int bHasZ, double dfMaxAngleStepSizeDegrees, const char *const *papszOptions=nullptr)
	Converts an arc circle into an approximate line string. More...
static OGRCurve *	curveFromLineString (const OGRLineString *poLS, const char *const *papszOptions=nullptr)
	Try to convert a linestring approximating curves into a curve. More...

Detailed Description

Create geometry objects from well known text/binary.

Member Function Documentation

approximateArcAngles()

OGRGeometry * OGRGeometryFactory::approximateArcAngles ( double  dfCenterX, double  dfCenterY, double  dfZ, double  dfPrimaryRadius, double  dfSecondaryRadius, double  dfRotation, double  dfStartAngle, double  dfEndAngle, double  dfMaxAngleStepSizeDegrees, const bool  bUseMaxGap = false  )

static

Stroke arc to linestring.

Stroke an arc of a circle to a linestring based on a center point, radius, start angle and end angle, all angles in degrees.

If the dfMaxAngleStepSizeDegrees is zero, then a default value will be used. This is currently 4 degrees unless the user has overridden the value with the OGR_ARC_STEPSIZE configuration variable.

If the OGR_ARC_MAX_GAP configuration variable is set, the straight-line distance between adjacent pairs of interpolated points will be limited to the specified distance. If the distance between a pair of points exceeds this maximum, additional points are interpolated between the two points.

See also

CPLSetConfigOption()

Parameters

dfCenterX	center X
dfCenterY	center Y
dfZ	center Z
dfPrimaryRadius	X radius of ellipse.
dfSecondaryRadius	Y radius of ellipse.
dfRotation	rotation of the ellipse clockwise.
dfStartAngle	angle to first point on arc (clockwise of X-positive)
dfEndAngle	angle to last point on arc (clockwise of X-positive)
dfMaxAngleStepSizeDegrees	the largest step in degrees along the arc, zero to use the default setting.
bUseMaxGap	Optional: whether to honor OGR_ARC_MAX_GAP.

Returns

OGRLineString geometry representing an approximation of the arc.

Since

OGR 1.8.0

createFromFgf()

OGRErr OGRGeometryFactory::createFromFgf ( const void *  pabyData, OGRSpatialReference *  poSR, OGRGeometry **  ppoReturn, int  nBytes = -1, int *  pnBytesConsumed = nullptr  )

static

Create a geometry object of the appropriate type from its FGF (FDO Geometry Format) binary representation.

Also note that this is a static method, and that there is no need to instantiate an OGRGeometryFactory object.

The C function OGR_G_CreateFromFgf() is the same as this method.

Parameters

pabyData	pointer to the input BLOB data.
poSR	pointer to the spatial reference to be assigned to the created geometry object. This may be NULL.
ppoReturn	the newly created geometry object will be assigned to the indicated pointer on return. This will be NULL in case of failure, but NULL might be a valid return for a NULL shape.
nBytes	the number of bytes available in pabyData.
pnBytesConsumed	if not NULL, it will be set to the number of bytes consumed (at most nBytes).

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.

createFromGeoJson() [1/2]

OGRGeometry * OGRGeometryFactory::createFromGeoJson ( const char *  pszJsonString, int  nSize = -1  )

static

Create geometry from GeoJson fragment.

Parameters

pszJsonString	The GeoJSON fragment for the geometry.
nSize	(new in GDAL 3.4) Optional length of the string if it is not null-terminated

Returns

a geometry on success, or NULL on error.

Since

GDAL 2.3

createFromGeoJson() [2/2]

OGRGeometry * OGRGeometryFactory::createFromGeoJson ( const CPLJSONObject &  oJsonObject )

static

Create geometry from GeoJson fragment.

Parameters

oJsonObject

The JSONObject class describes the GeoJSON geometry.

Returns

a geometry on success, or NULL on error.

Since

GDAL 2.3

createFromGEOS()

OGRGeometry * OGRGeometryFactory::createFromGEOS ( GEOSContextHandle_t  hGEOSCtxt, GEOSGeom  geosGeom  )

static

Builds a OGRGeometry* from a GEOSGeom.

Parameters

hGEOSCtxt	GEOS context
geosGeom	GEOS geometry

Returns

a OGRGeometry*

createFromGML()

OGRGeometry * OGRGeometryFactory::createFromGML ( const char *  pszData )

static

Create geometry from GML.

This method translates a fragment of GML containing only the geometry portion into a corresponding OGRGeometry. There are many limitations on the forms of GML geometries supported by this parser, but they are too numerous to list here.

The following GML2 elements are parsed : Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, MultiGeometry.

The following GML3 elements are parsed : Surface, MultiSurface, PolygonPatch, Triangle, Rectangle, Curve, MultiCurve, LineStringSegment, Arc, Circle, CompositeSurface, OrientableSurface, Solid, Tin, TriangulatedSurface.

Arc and Circle elements are returned as curves by default. Stroking to linestrings can be done with OGR_G_ForceTo(hGeom, OGR_GT_GetLinear(OGR_G_GetGeometryType(hGeom)), NULL). A 4 degrees step is used by default, unless the user has overridden the value with the OGR_ARC_STEPSIZE configuration variable.

The C function OGR_G_CreateFromGML() is the same as this method.

Parameters

pszData

The GML fragment for the geometry.

Returns

a geometry on success, or NULL on error.

See also

OGR_G_ForceTo()

OGR_GT_GetLinear()

OGR_G_GetGeometryType()

createFromWkb() [1/2]

OGRErr OGRGeometryFactory::createFromWkb ( const void *  pabyData, const OGRSpatialReference *  poSR, OGRGeometry **  ppoReturn, size_t  nBytes = static_cast<size_t>(-1), OGRwkbVariant  eWkbVariant = wkbVariantOldOgc  )

static

Create a geometry object of the appropriate type from its well known binary representation.

Note that if nBytes is passed as zero, no checking can be done on whether the pabyData is sufficient. This can result in a crash if the input data is corrupt. This function returns no indication of the number of bytes from the data source actually used to represent the returned geometry object. Use OGRGeometry::WkbSize() on the returned geometry to establish the number of bytes it required in WKB format.

Also note that this is a static method, and that there is no need to instantiate an OGRGeometryFactory object.

The C function OGR_G_CreateFromWkb() is the same as this method.

Parameters

pabyData	pointer to the input BLOB data.
poSR	pointer to the spatial reference to be assigned to the created geometry object. This may be NULL.
ppoReturn	the newly created geometry object will be assigned to the indicated pointer on return. This will be NULL in case of failure. If not NULL, *ppoReturn should be freed with OGRGeometryFactory::destroyGeometry() after use.
nBytes	the number of bytes available in pabyData, or -1 if it isn't known
eWkbVariant	WKB variant.

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.

createFromWkb() [2/2]

OGRErr OGRGeometryFactory::createFromWkb ( const void *  pabyData, const OGRSpatialReference *  poSR, OGRGeometry **  ppoReturn, size_t  nBytes, OGRwkbVariant  eWkbVariant, size_t &  nBytesConsumedOut  )

static

Create a geometry object of the appropriate type from its well known binary representation.

Note that if nBytes is passed as zero, no checking can be done on whether the pabyData is sufficient. This can result in a crash if the input data is corrupt. This function returns no indication of the number of bytes from the data source actually used to represent the returned geometry object. Use OGRGeometry::WkbSize() on the returned geometry to establish the number of bytes it required in WKB format.

Also note that this is a static method, and that there is no need to instantiate an OGRGeometryFactory object.

The C function OGR_G_CreateFromWkb() is the same as this method.

Parameters

pabyData	pointer to the input BLOB data.
poSR	pointer to the spatial reference to be assigned to the created geometry object. This may be NULL.
ppoReturn	the newly created geometry object will be assigned to the indicated pointer on return. This will be NULL in case of failure. If not NULL, *ppoReturn should be freed with OGRGeometryFactory::destroyGeometry() after use.
nBytes	the number of bytes available in pabyData, or -1 if it isn't known
eWkbVariant	WKB variant.
nBytesConsumedOut	output parameter. Number of bytes consumed.

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.

Since

GDAL 2.3

createFromWkt() [1/3]

static OGRErr OGRGeometryFactory::createFromWkt ( char **  ppszInput, const OGRSpatialReference *  poSRS, OGRGeometry **  ppoGeom  )

inlinestatic

Deprecated.

Deprecated:

in GDAL 2.3

createFromWkt() [2/3]

OGRErr OGRGeometryFactory::createFromWkt ( const char **  ppszData, const OGRSpatialReference *  poSR, OGRGeometry **  ppoReturn  )

static

Create a geometry object of the appropriate type from its well known text representation.

The C function OGR_G_CreateFromWkt() is the same as this method.

Parameters

ppszData	input zero terminated string containing well known text representation of the geometry to be created. The pointer is updated to point just beyond that last character consumed.
poSR	pointer to the spatial reference to be assigned to the created geometry object. This may be NULL.
ppoReturn	the newly created geometry object will be assigned to the indicated pointer on return. This will be NULL if the method fails. If not NULL, *ppoReturn should be freed with OGRGeometryFactory::destroyGeometry() after use.

Example:

const char* wkt= "POINT(0 0)";
 
// cast because OGR_G_CreateFromWkt will move the pointer
char* pszWkt = (char*) wkt;
OGRSpatialReferenceH ref = OSRNewSpatialReference(NULL);
OGRGeometryH new_geom;
OSRSetAxisMappingStrategy(poSR, OAMS_TRADITIONAL_GIS_ORDER);
OGRErr err = OGR_G_CreateFromWkt(&pszWkt, ref, &new_geom);

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.

createFromWkt() [3/3]

OGRErr OGRGeometryFactory::createFromWkt ( const char *  pszData, const OGRSpatialReference *  poSR, OGRGeometry **  ppoReturn  )

static

Create a geometry object of the appropriate type from its well known text representation.

The C function OGR_G_CreateFromWkt() is the same as this method.

Parameters

pszData	input zero terminated string containing well known text representation of the geometry to be created.
poSR	pointer to the spatial reference to be assigned to the created geometry object. This may be NULL.
ppoReturn	the newly created geometry object will be assigned to the indicated pointer on return. This will be NULL if the method fails. If not NULL, *ppoReturn should be freed with OGRGeometryFactory::destroyGeometry() after use.

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.

Since

GDAL 2.3

createGeometry()

OGRGeometry * OGRGeometryFactory::createGeometry ( OGRwkbGeometryType  eGeometryType )

static

Create an empty geometry of desired type.

This is equivalent to allocating the desired geometry with new, but the allocation is guaranteed to take place in the context of the GDAL/OGR heap.

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

Parameters

eGeometryType

the type code of the geometry class to be instantiated.

Returns

the newly create geometry or NULL on failure. Should be freed with OGRGeometryFactory::destroyGeometry() after use.

curveFromLineString()

OGRCurve * OGRGeometryFactory::curveFromLineString ( const OGRLineString *  poLS, const char *const *  papszOptions = nullptr  )

static

Try to convert a linestring approximating curves into a curve.

This method can return a COMPOUNDCURVE, a CIRCULARSTRING or a LINESTRING.

This method is the reverse of curveFromLineString().

Parameters

poLS	handle to the geometry to convert.
papszOptions	options as a null-terminated list of strings. Unused for now. Must be set to NULL.

Returns

the converted geometry (ownership to caller).

Since

GDAL 2.0

curveToLineString()

OGRLineString * OGRGeometryFactory::curveToLineString ( double  x0, double  y0, double  z0, double  x1, double  y1, double  z1, double  x2, double  y2, double  z2, int  bHasZ, double  dfMaxAngleStepSizeDegrees, const char *const *  papszOptions = nullptr  )

static

Converts an arc circle into an approximate line string.

The arc circle is defined by a first point, an intermediate point and a final point.

The provided dfMaxAngleStepSizeDegrees is a hint. The discretization algorithm may pick a slightly different value.

So as to avoid gaps when rendering curve polygons that share common arcs, this method is guaranteed to return a line with reversed vertex if called with inverted first and final point, and identical intermediate point.

Parameters

x0	x of first point
y0	y of first point
z0	z of first point
x1	x of intermediate point
y1	y of intermediate point
z1	z of intermediate point
x2	x of final point
y2	y of final point
z2	z of final point
bHasZ	TRUE if z must be taken into account
dfMaxAngleStepSizeDegrees	the largest step in degrees along the arc, zero to use the default setting.
papszOptions	options as a null-terminated list of strings or NULL. Recognized options: ADD_INTERMEDIATE_POINT=STEALTH/YES/NO (Default to STEALTH). Determine if and how the intermediate point must be output in the linestring. If set to STEALTH, no explicit intermediate point is added but its properties are encoded in low significant bits of intermediate points and OGRGeometryFactory::curveFromLineString() can decode them. This is the best compromise for round-tripping in OGR and better results with PostGIS ST_LineToCurve(). If set to YES, the intermediate point is explicitly added to the linestring. If set to NO, the intermediate point is not explicitly added.

Returns

the converted geometry (ownership to caller).

Since

GDAL 2.0

destroyGeometry()

void OGRGeometryFactory::destroyGeometry ( OGRGeometry *  poGeom )

static

Destroy geometry object.

Equivalent to invoking delete on a geometry, but it guaranteed to take place within the context of the GDAL/OGR heap.

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

Parameters

poGeom

the geometry to deallocate.

forceTo()

OGRGeometry * OGRGeometryFactory::forceTo ( OGRGeometry *  poGeom, OGRwkbGeometryType  eTargetType, const char *const *  papszOptions = nullptr  )

static

Convert to another geometry type.

Tries to force the provided geometry to the specified geometry type.

It can promote 'single' geometry type to their corresponding collection type (see OGR_GT_GetCollection()) or the reverse. non-linear geometry type to their corresponding linear geometry type (see OGR_GT_GetLinear()), by possibly approximating circular arcs they may contain. Regarding conversion from linear geometry types to curve geometry types, only "wrapping" will be done. No attempt to retrieve potential circular arcs by de-approximating stroking will be done. For that, OGRGeometry::getCurveGeometry() can be used.

The passed in geometry is consumed and a new one returned (or potentially the same one).

Starting with GDAL 3.9, this method honours the dimensionality of eTargetType.

Parameters

poGeom	the input geometry - ownership is passed to the method.
eTargetType	target output geometry type.
papszOptions	options as a null-terminated list of strings or NULL.

Returns

new geometry, or nullptr in case of error.

Since

GDAL 2.0

forceToLineString()

OGRGeometry * OGRGeometryFactory::forceToLineString ( OGRGeometry *  poGeom, bool  bOnlyInOrder = true  )

static

Convert to line string.

Tries to force the provided geometry to be a line string. This nominally effects a change on multilinestrings. In GDAL 2.0, for polygons or curvepolygons that have a single exterior ring, it will return the ring. For circular strings or compound curves, it will return an approximated line string.

The passed in geometry is consumed and a new one returned (or potentially the same one).

Parameters

poGeom	the input geometry - ownership is passed to the method.
bOnlyInOrder	flag that, if set to FALSE, indicate that the order of points in a linestring might be reversed if it enables to match the extremity of another linestring. If set to TRUE, the start of a linestring must match the end of another linestring.

Returns

new geometry.

forceToMultiLineString()

OGRGeometry * OGRGeometryFactory::forceToMultiLineString ( OGRGeometry *  poGeom )

static

Convert to multilinestring.

Tries to force the provided geometry to be a multilinestring.

• linestrings are placed in a multilinestring.
• circularstrings and compoundcurves will be approximated and placed in a multilinestring.
• geometry collections will be converted to multilinestring if they only contain linestrings.
• polygons will be changed to a collection of linestrings (one per ring).
• curvepolygons will be approximated and changed to a collection of ( linestrings (one per ring).

The passed in geometry is consumed and a new one returned (or potentially the same one).

Returns

new geometry.

forceToMultiPoint()

OGRGeometry * OGRGeometryFactory::forceToMultiPoint ( OGRGeometry *  poGeom )

static

Convert to multipoint.

Tries to force the provided geometry to be a multipoint. Currently this just effects a change on points or collection of points. The passed in geometry is consumed and a new one returned (or potentially the same one).

Returns

new geometry.

forceToMultiPolygon()

OGRGeometry * OGRGeometryFactory::forceToMultiPolygon ( OGRGeometry *  poGeom )

static

Convert to multipolygon.

Tries to force the provided geometry to be a multipolygon. Currently this just effects a change on polygons. The passed in geometry is consumed and a new one returned (or potentially the same one).

Returns

new geometry.

forceToPolygon()

OGRGeometry * OGRGeometryFactory::forceToPolygon ( OGRGeometry *  poGeom )

static

Convert to polygon.

Tries to force the provided geometry to be a polygon. This effects a change on multipolygons. Starting with GDAL 2.0, curve polygons or closed curves will be changed to polygons. The passed in geometry is consumed and a new one returned (or potentially the same one).

Note: the resulting polygon may break the Simple Features rules for polygons, for example when converting from a multi-part multipolygon.

Parameters

poGeom

the input geometry - ownership is passed to the method.

Returns

new geometry.

GetCurveParameters()

int OGRGeometryFactory::GetCurveParameters ( double  x0, double  y0, double  x1, double  y1, double  x2, double  y2, double &  R, double &  cx, double &  cy, double &  alpha0, double &  alpha1, double &  alpha2  )

static

Returns the parameter of an arc circle.

Angles are return in radians, with trigonometic convention (counter clock wise)

Parameters

x0	x of first point
y0	y of first point
x1	x of intermediate point
y1	y of intermediate point
x2	x of final point
y2	y of final point
R	radius (output)
cx	x of arc center (output)
cy	y of arc center (output)
alpha0	angle between center and first point, in radians (output)
alpha1	angle between center and intermediate point, in radians (output)
alpha2	angle between center and final point, in radians (output)

Returns

TRUE if the points are not aligned and define an arc circle.

Since

GDAL 2.0

haveGEOS()

bool OGRGeometryFactory::haveGEOS ( )

static

Test if GEOS enabled.

This static method returns TRUE if GEOS support is built into OGR, otherwise it returns FALSE.

Returns

TRUE if available, otherwise FALSE.

organizePolygons()

OGRGeometry * OGRGeometryFactory::organizePolygons ( OGRGeometry **  papoPolygons, int  nPolygonCount, int *  pbIsValidGeometry, const char **  papszOptions = nullptr  )

static

Organize polygons based on geometries.

Analyse a set of rings (passed as simple polygons), and based on a geometric analysis convert them into a polygon with inner rings, (or a MultiPolygon if dealing with more than one polygon) that follow the OGC Simple Feature specification.

All the input geometries must be OGRPolygon/OGRCurvePolygon with only a valid exterior ring (at least 4 points) and no interior rings.

The passed in geometries become the responsibility of the method, but the papoPolygons "pointer array" remains owned by the caller.

For faster computation, a polygon is considered to be inside another one if a single point of its external ring is included into the other one. (unless 'OGR_DEBUG_ORGANIZE_POLYGONS' configuration option is set to TRUE. In that case, a slower algorithm that tests exact topological relationships is used if GEOS is available.)

In cases where a big number of polygons is passed to this function, the default processing may be really slow. You can skip the processing by adding METHOD=SKIP to the option list (the result of the function will be a multi-polygon with all polygons as toplevel polygons) or only make it analyze counterclockwise polygons by adding METHOD=ONLY_CCW to the option list if you can assume that the outline of holes is counterclockwise defined (this is the convention for example in shapefiles, Personal Geodatabases or File Geodatabases).

For FileGDB, in most cases, but not always, a faster method than ONLY_CCW can be used. It is CCW_INNER_JUST_AFTER_CW_OUTER. When using it, inner rings are assumed to be counterclockwise oriented, and following immediately the outer ring (clockwise oriented) that they belong to. If that assumption is not met, an inner ring could be attached to the wrong outer ring, so this method must be used with care.

If the OGR_ORGANIZE_POLYGONS configuration option is defined, its value will override the value of the METHOD option of papszOptions (useful to modify the behavior of the shapefile driver)

Parameters

papoPolygons	array of geometry pointers - should all be OGRPolygons or OGRCurvePolygons. Ownership of the geometries is passed, but not of the array itself.
nPolygonCount	number of items in papoPolygons
pbIsValidGeometry	value may be set to FALSE if an invalid result is detected. Validity checks vary according to the method used and are are limited to what is needed to link inner rings to outer rings, so a result of TRUE does not mean that OGRGeometry::IsValid() returns TRUE.
papszOptions	a list of strings for passing options

Returns

a single resulting geometry (either OGRPolygon, OGRCurvePolygon, OGRMultiPolygon, OGRMultiSurface or OGRGeometryCollection). Returns a POLYGON EMPTY in the case of nPolygonCount being 0.

removeLowerDimensionSubGeoms()

OGRGeometry * OGRGeometryFactory::removeLowerDimensionSubGeoms ( const OGRGeometry *  poGeom )

static

Remove sub-geometries from a geometry collection that do not have the maximum topological dimensionality of the collection.

This is typically to be used as a cleanup phase after running OGRGeometry::MakeValid()

For example, MakeValid() on a polygon can return a geometry collection of polygons and linestrings. Calling this method will return either a polygon or multipolygon by dropping those linestrings.

On a non-geometry collection, this will return a clone of the passed geometry.

Parameters

poGeom

input geometry

Returns

a new geometry.

Since

GDAL 3.1.0

transformWithOptions()

OGRGeometry * OGRGeometryFactory::transformWithOptions ( const OGRGeometry *  poSrcGeom, OGRCoordinateTransformation *  poCT, char **  papszOptions, const TransformWithOptionsCache &  cache = TransformWithOptionsCache()  )

static

Transform a geometry.

Parameters

poSrcGeom	source geometry
poCT	coordinate transformation object, or NULL.
papszOptions	options. Including WRAPDATELINE=YES and DATELINEOFFSET=.
cache	Cache. May increase performance if persisted between invocations

Returns

(new) transformed geometry.

---

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

• ogr_geometry.h
• ogrgeometryfactory.cpp