STRTree Generation and Usage

Functions
vectorGeometryVector *	buildGEOSGeometriesFromFile (const char *filePath, const char *layerName, const char *inputReferenceSystem)
	Create a vector of GEOS geometries from an OGR-readable vector dataset.
GEOSSTRtree *	buildSTRTreefromRaster (const struct averagedData *data, const struct geoTransform *transformation, cellGeometryList **cells)
	Build a STRTree of vectorized raster cells and their values.
void	trackIntersectingGeometries (void *item, void *userdata)
	Callback used when querying STRTree.
intersectionVector *	querySTRTree (vectorGeometryVector *areasOfInterest, GEOSSTRtree *rasterTree)
	Query STRTree with MBRs of "extraction" geometries.
GEOSGeometry *	boundingBoxOfOGRToGEOS (const OGRGeometryH geom)
	Convert the MBR of an OGR geometry to a GEOS geometry.

Detailed Description

Function Documentation

boundingBoxOfOGRToGEOS()

GEOSGeometry * boundingBoxOfOGRToGEOS ( const OGRGeometryH geom )

nodiscard

Convert the MBR of an OGR geometry to a GEOS geometry.

Note

After the function returns, the caller owns the returned GEOSGeometry object and must free/destroy it after use.

Parameters

geom	OGR geometry whose MBR should be converted.

Returns

GEOSGeometry* MBR of input geometry.

buildGEOSGeometriesFromFile()

vectorGeometryVector * buildGEOSGeometriesFromFile ( const char * filePath, const char * layerName, const char * inputReferenceSystem )

nodiscard

Create a vector of GEOS geometries from an OGR-readable vector dataset.

This functions opens an OGR-readable vector dataset and extracts a single layer from it. Every feature of the extracted layer is exported to a GEOS geometry and possibly transformed if the layer CRS does not match the one provided in inputReferenceSystem. No attribute information of the layer features is stored/exported.

Remarks

Geometries that don't describe an area or are not the strict 2D version are not allowed and return an error. It's assumed that only one geometry type is associated with each feature.

Note

After the function returns, the caller owns the returned object and musst free it after use.

Parameters

filePath	Path to vector dataset.
layerName	Layer to extract. If NULL, the first layer will be used.
inputReferenceSystem	Target CRS in WKT representation.

Returns

vectorGeometryVector* Reference to vector of GEOS geometries, NULL on error.

buildSTRTreefromRaster()

GEOSSTRtree * buildSTRTreefromRaster ( const struct averagedData * data, const struct geoTransform * transformation, cellGeometryList ** cells )

nodiscard

Build a STRTree of vectorized raster cells and their values.

This function creates a new STRTree object and inserts vectorized raster cells and their values. The individual cells are also stored in the cells list because the STRTree does not allow to return references to inserted items. GDAL's geo transfromation information is used to derive vectorized cell geometries as per GDAL's documentation. Thus, this function should work well even with non north-up raster datasets as the rotation is honored.

Note

After the function returns, the caller owns the returned GEOSTree object and musst free it after use.

Parameters

data	Averaged data.
transformation	Extracted geo transfomation information used to create vectorized cells.
cells	Indirect reference to linked list storing vectorzied geometries. Will not point to valid list on error.

Returns

GEOSSTRtree* Reference to STRTree, NULL on error

querySTRTree()

intersectionVector * querySTRTree ( vectorGeometryVector * areasOfInterest, GEOSSTRtree * rasterTree )

nodiscard

Query STRTree with MBRs of "extraction" geometries.

This function iterates over all geometries stored in areaOfInterest and queries the previously created STRTree, consisting of vectorized raster cells, for intersections. Any intersecting cells are added to a list and may be used to calculate area weighted means of total water column.

Note

After the function returns, the caller owns the returned object and musst free it after use.

Parameters

areasOfInterest	Vector of "overlay" geometries used to query STRTree.
rasterTree	STRTree of vectorized raster cells.

Returns

intersectionVector* Reference to vector connecting "overlay" geometries to intersecting vectorized raster cells.

trackIntersectingGeometries()

void trackIntersectingGeometries	(	void *	item,
		void *	userdata )

Callback used when querying STRTree.

Add a new entry to a linked list holding cell geometries. I.e. a list of vectorized raster cells for a given query polygon.

Parameters

item	void-casted cellGeometry object whose MBR intersects with MBR of query polygon.
userdata	void-casted reference to userdata_t.