GDAL

Create geometry objects from well known text/binary. More...
#include <ogr_geometry.h>
Static Public Member Functions  
static OGRErr  createFromWkb (unsigned char *, OGRSpatialReference *, OGRGeometry **, int=1, OGRwkbVariant=wkbVariantOldOgc) 
Create a geometry object of the appropriate type from it's well known binary representation. More...  
static OGRErr  createFromWkb (const unsigned char *pabyData, OGRSpatialReference *, OGRGeometry **, int nSize, OGRwkbVariant eVariant, int &nBytesConsumedOut) 
Create a geometry object of the appropriate type from it's well known binary representation. More...  
static OGRErr  createFromWkt (char **, OGRSpatialReference *, OGRGeometry **) 
Create a geometry object of the appropriate type from it's well known text representation. More...  
static OGRErr  createFromFgf (unsigned char *, OGRSpatialReference *, OGRGeometry **, int=1, int *=NULL) 
Create a geometry object of the appropriate type from it's 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 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=NULL) 
Convert to another geometry type. More...  
static OGRGeometry *  organizePolygons (OGRGeometry **papoPolygons, int nPolygonCount, int *pbResultValidGeometry, const char **papszOptions=NULL) 
Organize polygons based on geometries. More...  
static bool  haveGEOS () 
Test if GEOS enabled. More...  
static OGRGeometry *  transformWithOptions (const OGRGeometry *poSrcGeom, OGRCoordinateTransformation *poCT, char **papszOptions) 
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) 
Stroke arc to linestring. More...  
static int  GetCurveParmeters (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=NULL) 
Converts an arc circle into an approximate line string. More...  
static OGRCurve *  curveFromLineString (const OGRLineString *poLS, const char *const *papszOptions=NULL) 
Try to convert a linestring approximating curves into a curve. More...  
Create geometry objects from well known text/binary.

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.
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 Xpositive) 
dfEndAngle  angle to last point on arc (clockwise of Xpositive) 
dfMaxAngleStepSizeDegrees  the largest step in degrees along the arc, zero to use the default setting. 

static 
Create a geometry object of the appropriate type from it's 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.
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). 

static 
Builds a OGRGeometry* from a GEOSGeom.
hGEOSCtxt  GEOS context 
geosGeom  GEOS geometry 

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.
(OGR >= 1.8.0) 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 stroked to linestring, by using a 4 degrees step, 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.
pszData  The GML fragment for the geometry. 

static 
Create a geometry object of the appropriate type from it's 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.
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. 

static 
Create a geometry object of the appropriate type from it's 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.
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. 

static 
Create a geometry object of the appropriate type from it's well known text representation.
The C function OGR_G_CreateFromWkt() is the same as this method.
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; OGRErr err = OGR_G_CreateFromWkt(&pszWkt, ref, &new_geom);

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().
eGeometryType  the type code of the geometry class to be instantiated. 

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().
poLS  handle to the geometry to convert. 
papszOptions  options as a nullterminated list of strings. Unused for now. Must be set to NULL. 

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.
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 nullterminated list of strings or NULL. Recognized options:


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().
poGeom  the geometry to deallocate. 

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. nonlinear 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 "wraping" will be done. No attempt to retrieve potential circular arcs by deapproximating 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).
poGeom  the input geometry  ownership is passed to the method. 
eTargetType  target output geometry type. 
papszOptions  options as a nullterminated list of strings or NULL. 

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).
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. 

static 
Convert to multilinestring.
Tries to force the provided geometry to be a multilinestring.
The passed in geometry is consumed and a new one returned (or potentially the same one).

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).

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).

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).
poGeom  the input geometry  ownership is passed to the method. 

static 
Returns the parameter of an arc circle.
Angles are return in radians, with trigonometic convention (counter clock wise)
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) 

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

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 multipolygon 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 behaviour of the shapefile driver)
papoPolygons  array of geometry pointers  should all be OGRPolygons. Ownership of the geometries is passed, but not of the array itself. 
nPolygonCount  number of items in papoPolygons 
pbIsValidGeometry  value will be set TRUE if result is valid or FALSE otherwise. 
papszOptions  a list of strings for passing options 

static 
Transform a geometry.
poSrcGeom  source geometry 
poCT  coordinate transformation object. 
papszOptions  options. Including WRAPDATELINE=YES. 