Abstract class that represents viewshed calculation from this class specific implementations ( Viewshed and InverseViewshed) are derived. Class provides all the base functions for those algorithms, including implementation of plane sweep algorithm for viewshed according to Van Kreveld(1996) and Haverkort et al(2007), as implemented in GRASS GIS described by Toma et al. (2022). More...

#include <abstractviewshed.h>

Inheritance diagram for viewshed::AbstractViewshed:

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Collaboration diagram for viewshed::AbstractViewshed:

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Public Member Functions
void	initEventList ()
	Create event list for line sweep algorithm from input raster.
void	sortEventList ()
	Sort event list for parsing.
void	parseEventList (std::function< void(int, int)> progressCallback=[](int, int) {})
	Parse event list by individual events.
bool	extractValuesFromEventList (std::shared_ptr< ProjectedSquareCellRaster > dem_, std::string fileName, std::function< double(LoSNode)> func)
	Extract values from event list into a raster and save it to file.
bool	isInsideAngles (const double &eventEnterAngle, const double &eventExitAngle)
	Checks if cell with these enter and exit angles falls inside the angle limit.
void	setMaximalDistance (double distance)
	Set the Maximal Distance limit value. Limits event list creation to cells within this distance limit. Value is in the same units as CRS of input raster.
void	setAngles (double minAngle, double maxAngle)
	Set horizontal angle limits for viewshed calculation. 0.
void	setMaxConcurentTasks (int maxTasks)
	Set the number of maximum Concurent Taks that can be prepared in thread pool for processing.
void	setMaxThreads (int threads)
	Set the maximal number of threads that can be used for calculation.
void	prepareMemoryRasters ()
	Initialized output rasters in memory.
virtual void	calculate (std::function< void(std::string, double)> stepsTimingCallback=[](std::string text, double time) {}, std::function< void(int, int)> progressCallback=[](int, int) {})=0
	Calculate the viewshed. Covers all the steps - create list of events, sort list of events, parse list of events.
virtual void	addEventsFromCell (int &row, int &column, const double &pixelValue, bool &solveCell)=0
	Function that creates events for event list from given cell.
virtual void	submitToThreadpool (const CellEvent &e)=0
	Submit LoS with this CellEvent to threadpool for solving.
std::shared_ptr< SingleBandRaster >	resultRaster (int index=0)
	Extract individual result raster.
bool	saveResults (std::string location, std::string fileNamePrefix="")
	Save all result rasters into the folder, optionally using name prefix.
LoSNode	statusNodeFromPoint (OGRPoint point)
	Create LoSNode from OGRPoint.
OGRPoint	point (int row, int col)
	Create OGRPoint with coordinates of given row and column in the raster.
void	setDefaultResultDataType (GDALDataType dataType)
	Set the Default Result Data Type to use in output rasters.
long	numberOfValidCells ()
	Number of valid cells in raster - cells not containing no data.
long	numberOfCellEvents ()
	Number of events in event list.
bool	isValid ()
	Check if the viewshed is valid, meaning that the important point is valid.
bool	hasError ()
	Check if an error occurred during calculation (e.g. in one of the worker threads).
std::string	errorMessage ()
	Message of the first error that occurred during calculation, empty string if there was none.
void	setVisibilityMask (std::shared_ptr< ProjectedSquareCellRaster > mask)
	Set the Visibility Mask for viewshed calculation.
long long	totalCountOfLoSNodes ()
	Overall number of solved LoSNodes in all evaluated LoS.
long long	sizeOfEvents ()
	Size of cell event list in bytes.
long long	totalSizeOfLoS ()
	Overall size of all solved LoS in bytes.
long long	meanSizeOfLoS ()
	Mean size of solved LoS in bytes.
double	initLastedSeconds ()
	Number of seconds the creation of event list lasted.
double	sortLastedSeconds ()
	Number of seconds the sort of event list lasted.
double	parseLastedSeconds ()
	Number of seconds the parsing of event list lasted.
double	processingLastedSeconds ()
	Number of seconds the calculation of viewshed indexes lasted.
long long	sizeOfOutputRaster ()
	Size in bytes that one output raster takes.
int	numberOfResultRasters ()
	Number of output rasters. Equals number of input algorithms.
long long	sizeOfOutputRasters ()
	Size in bytes that all output raster takes.
CellEvent	cellEvent (size_t i)
	Extract individual cell event from cell events.
virtual void	calculateVisibilityRaster ()=0
	Calculate visibility mask of areas which are visible from point (visibility), or from which the points is visible (inverse visibility). The visibility raster is calculated using fast algorithm, significantly faster than algorithms with visibility indices.
bool	saveVisibilityRaster (std::string filePath)
	Save visibility raster to file.
void	calculateVisibilityMask ()
	Calculate visibility mask raster.

Protected Member Functions
void	recordTaskError (const std::string &message)
	Store error message from a calculation task, keeping only the first one recorded.
std::vector< LoSNode >	prepareLoSWithPoint (OGRPoint point)
bool	validAngles ()

Protected Attributes
std::vector< LoSNode >	mLosNodes
	LoSNodes in currently solved LoS while parsing event list.
std::vector< CellEvent >	mCellEvents
	Event list. All cell events for the input raster.
std::shared_ptr< ProjectedSquareCellRaster >	mInputDsm
	Input raster with digital surface model.
std::shared_ptr< ProjectedSquareCellRaster >	mVisibilityMask = nullptr
	Input raster with visibility calculation mask.
std::shared_ptr< Point >	mPoint
	Important point for visibility calculation. Either viewpoint (normal viewshed) or target point (inverse viewshed).
std::shared_ptr< ViewshedAlgorithms >	mVisibilityIndices
	Visibility indexes to calculate while calculating this viewshed. As AbstractViewshedAlgorithm.
GDALDataType	mDataType = OUTPUT_RASTER_DATA_TYPE
	Data type of output rasters.
int	mDefaultBand = 1
	Default band to read from rasters.
long	mValidCells = 0
long	mTotalLosNodesCount = 0
long	mNumberOfLos = 0
bool	mInverseViewshed = false
double	mMaxDistance = std::numeric_limits<double>::max()
double	mMinAngle = std::numeric_limits<double>::quiet_NaN()
double	mMaxAngle = std::numeric_limits<double>::quiet_NaN()
int	mMaxNumberOfTasks = 100
	Maximal number of LoS to solve, that can be stored in threadpool.
double	mCellSize = 0
bool	mValid = false
std::mutex	mTaskErrorMutex
	Guards access to mTaskError, which can be written from worker threads.
std::string	mTaskError
	First error that occurred during calculation, empty if there was none.
bool	mCurvatureCorrections = false
double	mEarthDiameter = EARTH_DIAMETER
double	mRefractionCoefficient = REFRACTION_COEFFICIENT
LoSNode	mLosNodePoint
BS::thread_pool	mThreadPool
	Threadpool that takes care of preparing individual threads with LoS to be solved.
std::shared_ptr< ResultRasters >	mResults = std::make_shared<ResultRasters>()
std::shared_ptr< ProjectedSquareCellRaster >	mVisibilityRaster = nullptr
std::chrono::nanoseconds	mTimeInit
std::chrono::nanoseconds	mTimeSort
std::chrono::nanoseconds	mTimeParse
double	mCellElevs [3]
double	mAngleCenter
double	mAngleEnter
double	mAngleExit
double	mEventDistance
CellEvent	mEventCenter
CellEvent	mEventEnter
CellEvent	mEventExit = CellEvent()
CellEvent	mEventEnterOpposite
CellEvent	mEventExitOpposite = CellEvent()
double	mOppositeAngleEnter
double	mOppositeAngleExit
LoSNode	mLoSNodeTemp = LoSNode()

Detailed Description

Abstract class that represents viewshed calculation from this class specific implementations ( Viewshed and InverseViewshed) are derived. Class provides all the base functions for those algorithms, including implementation of plane sweep algorithm for viewshed according to Van Kreveld(1996) and Haverkort et al(2007), as implemented in GRASS GIS described by Toma et al. (2022).

VAN KREVELD, M. Variations on Sweep Algorithms: efficient computation of extended viewsheds and class intervals. Utrecht: Utrecht University: Information and Computing Sciences, 1996.

HAVERKORT, H., TOMA, L., ZHUANG, Y. Computing Visibility on Terrains in External Memory. ACM Journal on Experimental Algorithmics, 13, 2009.

TOMA, L., ZHUANG, Y., RICHARD, W., METZ, M. Grass gis manual: r.viewshed, 2022. https://grass.osgeo.org/grass82/manuals/r.viewshed.html.

Member Function Documentation

◆ addEventsFromCell()

virtual void viewshed::AbstractViewshed::addEventsFromCell	(	int &	row,
		int &	column,
		const double &	pixelValue,
		bool &	solveCell )

pure virtual

Function that creates events for event list from given cell.

Parameters

row
column
pixelValue
rasterBlock
solveCell	Based on mask value, information whether center event for this cell should be created.

Implemented in InverseViewshed, Viewshed, viewshed::InverseViewshed, and viewshed::Viewshed.

◆ calculate()

virtual void viewshed::AbstractViewshed::calculate	(	std::function< void(std::string, double)>	stepsTimingCallback = [](std::string text, double time) {},
		std::function< void(int, int)>	progressCallback = [](int, int) {} )

pure virtual

Calculate the viewshed. Covers all the steps - create list of events, sort list of events, parse list of events.

Parameters

stepsTimingCallback	Callback function outputing message how long individual step takes.
progressCallback	Callback function outputing processes part of event list.

Implemented in InverseViewshed, Viewshed, viewshed::InverseViewshed, and viewshed::Viewshed.

◆ calculateVisibilityRaster()

virtual void viewshed::AbstractViewshed::calculateVisibilityRaster ( )

pure virtual

Calculate visibility mask of areas which are visible from point (visibility), or from which the points is visible (inverse visibility). The visibility raster is calculated using fast algorithm, significantly faster than algorithms with visibility indices.

Implemented in InverseViewshed, Viewshed, viewshed::InverseViewshed, and viewshed::Viewshed.

◆ cellEvent()

CellEvent viewshed::AbstractViewshed::cellEvent ( size_t i )

inline

Extract individual cell event from cell events.

Parameters

i

Returns: CellEvent

◆ errorMessage()

std::string viewshed::AbstractViewshed::errorMessage ( )

inline

Message of the first error that occurred during calculation, empty string if there was none.

Returns: std::string

◆ extractValuesFromEventList()

bool AbstractViewshed::extractValuesFromEventList	(	std::shared_ptr< ProjectedSquareCellRaster >	dem_,
		std::string	fileName,
		std::function< double(LoSNode)>	func )

Extract values from event list into a raster and save it to file.

Returns: true if the raster was successfully saved, false otherwise.

◆ hasError()

bool viewshed::AbstractViewshed::hasError ( )

inline

Check if an error occurred during calculation (e.g. in one of the worker threads).

Returns: true; false

◆ initLastedSeconds()

double viewshed::AbstractViewshed::initLastedSeconds ( )

inline

Number of seconds the creation of event list lasted.

Returns: double

◆ isInsideAngles()

bool AbstractViewshed::isInsideAngles	(	const double &	eventEnterAngle,
		const double &	eventExitAngle )

Checks if cell with these enter and exit angles falls inside the angle limit.

Parameters

eventEnterAngle
eventExitAngle

Returns: true; false

◆ isValid()

bool viewshed::AbstractViewshed::isValid ( )

inline

Check if the viewshed is valid, meaning that the important point is valid.

Returns: true; false

◆ meanSizeOfLoS()

long long viewshed::AbstractViewshed::meanSizeOfLoS ( )

inline

Mean size of solved LoS in bytes.

Returns: long long

◆ numberOfCellEvents()

long viewshed::AbstractViewshed::numberOfCellEvents ( )

inline

Number of events in event list.

Returns: long

◆ numberOfResultRasters()

int viewshed::AbstractViewshed::numberOfResultRasters ( )

inline

Number of output rasters. Equals number of input algorithms.

Returns: int

◆ numberOfValidCells()

long viewshed::AbstractViewshed::numberOfValidCells ( )

inline

Number of valid cells in raster - cells not containing no data.

Returns: long

◆ parseEventList()

void AbstractViewshed::parseEventList ( std::function< void(int, int)> progressCallback = []( int, int ) {} )

Parse event list by individual events.

Parameters

progressCallback Call function with arguments of elements done from total elements (both as intereger).

◆ parseLastedSeconds()

double viewshed::AbstractViewshed::parseLastedSeconds ( )

inline

Number of seconds the parsing of event list lasted.

Returns: double

◆ point()

OGRPoint AbstractViewshed::point	(	int	row,
		int	col )

Create OGRPoint with coordinates of given row and column in the raster.

Parameters

row
col

Returns: OGRPoint

◆ processingLastedSeconds()

double viewshed::AbstractViewshed::processingLastedSeconds ( )

inline

Number of seconds the calculation of viewshed indexes lasted.

Returns: double

◆ resultRaster()

std::shared_ptr< SingleBandRaster > AbstractViewshed::resultRaster ( int index = 0 )

Extract individual result raster.

Parameters

index

Returns: std::shared_ptr<SingleBandRaster>

◆ saveResults()

bool AbstractViewshed::saveResults	(	std::string	location,
		std::string	fileNamePrefix = "" )

Save all result rasters into the folder, optionally using name prefix.

Parameters

location
fileNamePrefix

Returns: true if all rasters were successfully saved, false if any save failed.

◆ saveVisibilityRaster()

bool AbstractViewshed::saveVisibilityRaster ( std::string filePath )

Save visibility raster to file.

Parameters

filePath

Returns: true if the raster was successfully saved, false otherwise.

◆ setAngles()

void AbstractViewshed::setAngles	(	double	minAngle,
		double	maxAngle )

Set horizontal angle limits for viewshed calculation. 0.

Parameters

minAngle
maxAngle

◆ setDefaultResultDataType()

void AbstractViewshed::setDefaultResultDataType ( GDALDataType dataType )

Set the Default Result Data Type to use in output rasters.

Parameters

dataType

◆ setMaxConcurentTasks()

void AbstractViewshed::setMaxConcurentTasks ( int maxTasks )

Set the number of maximum Concurent Taks that can be prepared in thread pool for processing.

Parameters

maxTasks

◆ setMaximalDistance()

void AbstractViewshed::setMaximalDistance ( double distance )

Set the Maximal Distance limit value. Limits event list creation to cells within this distance limit. Value is in the same units as CRS of input raster.

Parameters

distance

◆ setMaxThreads()

void AbstractViewshed::setMaxThreads ( int threads )

Set the maximal number of threads that can be used for calculation.

Parameters

threads

◆ setVisibilityMask()

void viewshed::AbstractViewshed::setVisibilityMask ( std::shared_ptr< ProjectedSquareCellRaster > mask )

inline

Set the Visibility Mask for viewshed calculation.

Parameters

mask

◆ sizeOfEvents()

long long viewshed::AbstractViewshed::sizeOfEvents ( )

inline

Size of cell event list in bytes.

Returns: long long

◆ sizeOfOutputRaster()

long long viewshed::AbstractViewshed::sizeOfOutputRaster ( )

inline

Size in bytes that one output raster takes.

Returns: long long

◆ sizeOfOutputRasters()

long long viewshed::AbstractViewshed::sizeOfOutputRasters ( )

inline

Size in bytes that all output raster takes.

Returns: long long

◆ sortLastedSeconds()

double viewshed::AbstractViewshed::sortLastedSeconds ( )

inline

Number of seconds the sort of event list lasted.

Returns: double

◆ statusNodeFromPoint()

LoSNode AbstractViewshed::statusNodeFromPoint ( OGRPoint point )

Create LoSNode from OGRPoint.

Parameters

point

Returns: LoSNode

◆ submitToThreadpool()

virtual void viewshed::AbstractViewshed::submitToThreadpool ( const CellEvent & e )

pure virtual

Submit LoS with this CellEvent to threadpool for solving.

Parameters

e

Implemented in viewshed::InverseViewshed, Viewshed, and viewshed::Viewshed.

◆ totalCountOfLoSNodes()

long long viewshed::AbstractViewshed::totalCountOfLoSNodes ( )

inline

Overall number of solved LoSNodes in all evaluated LoS.

Returns: long long

◆ totalSizeOfLoS()

long long viewshed::AbstractViewshed::totalSizeOfLoS ( )

inline

Overall size of all solved LoS in bytes.

Returns: long long

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

/home/runner/work/cpp-viewshed-library/cpp-viewshed-library/include/viewshed/abstractviewshed.h
/home/runner/work/cpp-viewshed-library/cpp-viewshed-library/src/library/visibility/abstractviewshed.cpp

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Member Function Documentation

◆ addEventsFromCell()

◆ calculate()

◆ calculateVisibilityRaster()

◆ cellEvent()

◆ errorMessage()

◆ extractValuesFromEventList()

◆ hasError()

◆ initLastedSeconds()

◆ isInsideAngles()

◆ isValid()

◆ meanSizeOfLoS()

◆ numberOfCellEvents()

◆ numberOfResultRasters()

◆ numberOfValidCells()

◆ parseEventList()

◆ parseLastedSeconds()

◆ point()

◆ processingLastedSeconds()

◆ resultRaster()

◆ saveResults()

◆ saveVisibilityRaster()

◆ setAngles()

◆ setDefaultResultDataType()

◆ setMaxConcurentTasks()

◆ setMaximalDistance()

◆ setMaxThreads()

◆ setVisibilityMask()

◆ sizeOfEvents()

◆ sizeOfOutputRaster()

◆ sizeOfOutputRasters()

◆ sortLastedSeconds()

◆ statusNodeFromPoint()

◆ submitToThreadpool()

◆ totalCountOfLoSNodes()

◆ totalSizeOfLoS()