Computes signed distance values from an initial iso-surface and optionally performs velocity extension at the same time. This is done by means of a novel sparse and parallel fast sweeping algorithm based on a first order Godunov's scheme. More...

#include <openvdb/tools/FastSweeping.h>

Classes
struct	DilateKernel
	Private class of FastSweeping to perform multi-threaded initialization. More...
struct	InitSdf
struct	MinMaxKernel
struct	PruneMinMaxFltKernel
struct	SweepingKernel
	Private class of FastSweeping to perform concurrent fast sweeping in two directions. More...

Public Member Functions
	FastSweeping ()
	Constructor.
	~FastSweeping ()
	Destructor.
	FastSweeping (const FastSweeping &)=delete
	Disallow copy construction.
FastSweeping &	operator= (const FastSweeping &)=delete
	Disallow copy assignment.
SdfGridT::Ptr	sdfGrid ()
	Returns a shared pointer to the signed distance field computed by this class.
ExtGridT::Ptr	extGrid ()
	Returns a shared pointer to the extension field computed by this class.
ExtGridT::Ptr	extGridInput ()
	Returns a shared pointer to the extension grid input. This is non-NULL if this class is used to extend a field with a non-default sweep direction.
bool	initSdf (const SdfGridT &sdfGrid, SdfValueT isoValue, bool isInputSdf)
	Initializer for input grids that are either a signed distance field or a scalar fog volume.
template<typename ExtOpT>
bool	initExt (const SdfGridT &sdfGrid, const ExtOpT &op, const ExtValueT &background, SdfValueT isoValue, bool isInputSdf, FastSweepingDomain mode=FastSweepingDomain::SWEEP_ALL, const typename ExtGridT::ConstPtr extGrid=nullptr)
	Initializer used whenever velocity extension is performed in addition to the computation of signed distance fields.
bool	initDilate (const SdfGridT &sdfGrid, int dilation, NearestNeighbors nn=NN_FACE, FastSweepingDomain mode=FastSweepingDomain::SWEEP_ALL)
	Initializer used when dilating an existing signed distance field.
template<typename MaskTreeT>
bool	initMask (const SdfGridT &sdfGrid, const Grid< MaskTreeT > &mask, bool ignoreActiveTiles=false)
	Initializer used for the extension of an existing signed distance field into the active values of an input mask of arbitrary value type.
void	sweep (int nIter=1, bool finalize=true)
	Perform nIter iterations of the fast sweeping algorithm.
void	clear ()
	Clears all the grids and counters so initialization can be called again.
size_t	sweepingVoxelCount () const
	Return the number of voxels that will be solved for.
size_t	boundaryVoxelCount () const
	Return the number of voxels that defined the boundary condition.
bool	isValid () const
	Return true if there are voxels and boundaries to solve for.
FastSweepingDomain	sweepDirection () const
	Return whether the sweep update is in all direction (SWEEP_ALL), greater than isovalue (SWEEP_GREATER_THAN_ISOVALUE), or less than isovalue (SWEEP_LESS_THAN_ISOVALUE).
bool	isInputSdf ()
	Return whether the fast-sweeping input grid a signed distance function or not (fog).
template<typename OpT>
bool	initExt (const SdfGridT &fogGrid, const OpT &op, const ExtValueT &background, SdfValueT isoValue, bool isInputSdf, FastSweepingDomain mode, const typename ExtGridT::ConstPtr extGrid)

Detailed Description

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>
class openvdb::v13_0::tools::FastSweeping< SdfGridT, ExtValueT >

Computes signed distance values from an initial iso-surface and optionally performs velocity extension at the same time. This is done by means of a novel sparse and parallel fast sweeping algorithm based on a first order Godunov's scheme.

Solves: $|\nabla \phi|^2 = 1$

Warning: Note, it is important to call one of the initialization methods before called the sweep function. Failure to do so will throw a RuntimeError. Consider instead call one of the many higher-level free-standing functions defined above!

Constructor & Destructor Documentation

◆ FastSweeping() [1/2]

template<typename SdfGridT, typename ExtValueT>

FastSweeping ( )

Constructor.

◆ ~FastSweeping()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

~FastSweeping ( )

inline

Destructor.

◆ FastSweeping() [2/2]

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

FastSweeping ( const FastSweeping< SdfGridT, ExtValueT > & )

delete

Disallow copy construction.

Member Function Documentation

◆ boundaryVoxelCount()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

size_t boundaryVoxelCount ( ) const

inline

Return the number of voxels that defined the boundary condition.

◆ clear()

template<typename SdfGridT, typename ExtValueT>

void clear ( )

Clears all the grids and counters so initialization can be called again.

◆ extGrid()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

ExtGridT::Ptr extGrid ( )

inline

Returns a shared pointer to the extension field computed by this class.

Warning: This shared pointer might point to NULL if the grid has not been initialize (by one of the init methods) or computed (by the sweep method).

◆ extGridInput()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

ExtGridT::Ptr extGridInput ( )

inline

Returns a shared pointer to the extension grid input. This is non-NULL if this class is used to extend a field with a non-default sweep direction.

Warning: This shared pointer might point to NULL. This is non-NULL if this class is used to extend a field with a non-default sweep direction, i.e. SWEEP_LESS_THAN_ISOVALUE or SWEEP_GREATER_THAN_ISOVALUE.

◆ initDilate()

template<typename SdfGridT, typename ExtValueT>

bool initDilate	(	const SdfGridT &	sdfGrid,
		int	dilation,
		NearestNeighbors	nn = NN_FACE,
		FastSweepingDomain	mode = FastSweepingDomain::SWEEP_ALL )

Initializer used when dilating an existing signed distance field.

Returns: True if the initialization succeeded.

Parameters

sdfGrid	Input signed distance field to to be dilated.
dilation	Numer of voxels that the input SDF will be dilated.
nn	Stencil-pattern used for dilation
mode	Determines the direction of the dilation. SWEEP_ALL will dilate in both sides of the signed distance function, SWEEP_GREATER_THAN_ISOVALUE will dilate in the positive side of the iso-surface, SWEEP_LESS_THAN_ISOVALUE will dilate in the negative side of the iso-surface.

This, or any of ther other initialization methods, should be called before any call to sweep(). Failure to do so will throw a RuntimeError.

Warning: Note, if this method fails, i.e. returns false, a subsequent call to sweep will trow a RuntimeError. Instead call clear and try again.

◆ initExt() [1/2]

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

template<typename OpT>

bool initExt	(	const SdfGridT &	fogGrid,
		const OpT &	op,
		const ExtValueT &	background,
		SdfValueT	isoValue,
		bool	isInputSdf,
		FastSweepingDomain	mode,
		const typename ExtGridT::ConstPtr	extGrid )

◆ initExt() [2/2]

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

template<typename ExtOpT>

bool initExt	(	const SdfGridT &	sdfGrid,
		const ExtOpT &	op,
		const ExtValueT &	background,
		SdfValueT	isoValue,
		bool	isInputSdf,
		FastSweepingDomain	mode = FastSweepingDomain::SWEEP_ALL,
		const typename ExtGridT::ConstPtr	extGrid = nullptr )

Initializer used whenever velocity extension is performed in addition to the computation of signed distance fields.

Returns: True if the initialization succeeded.

Parameters

sdfGrid	Input scalar grid that represents an existing signed distance field or a fog volume (signified by isInputSdf).
op	Functor with signature [](const Vec3R &xyz)->ExtValueT that defines the Dirichlet boundary condition, on the iso-surface, of the field to be extended. Strictly the return type of this functor is only required to be convertible to ExtValueT!
background	Background value of return grid with the extension field.
isoValue	Iso-value to be used for the boundary condition of the fast sweeping algorithm (typically 0 for sdfs and a positive value for fog volumes).
isInputSdf	Used to determine if sdfGrid is a sigend distance field (true) or a scalar fog volume (false).
mode	Determines the mode of updating the extension field. SWEEP_ALL will update all voxels of the extension field affected by the fast sweeping algorithm. SWEEP_GREATER_THAN_ISOVALUE will update all voxels corresponding to fog values that are greater than a given isovalue. SWEEP_LESS_THAN_ISOVALUE will update all voxels corresponding to fog values that are less than a given isovalue. If a mode other than SWEEP_ALL is chosen, a user needs to supply extGrid.
extGrid	Optional parameter required to supply a default value for the extension field when SWEEP_GREATER_THAN_ISOVALUE or SWEEP_LESS_THAN_ISOVALUE mode is picked for mode. When SWEEP_GREATER_THAN_ISOVALUE is supplied as an argument for mode, the extension field voxel will default to the value of the extGrid in that position if it corresponds to a level-set value that is less than the isovalue. Otherwise, the extension field voxel value will be computed by the Fast Sweeping algorithm. The opposite convention is implemented when SWEEP_LESS_THAN_ISOVALUE is supplied as an argument for mode.

This, or any of ther other initialization methods, should be called before any call to sweep(). Failure to do so will throw a RuntimeError.

Warning: Note, if this method fails, i.e. returns false, a subsequent call to sweep will trow a RuntimeError. Instead call clear and try again.

◆ initMask()

template<typename SdfGridT, typename ExtValueT>

template<typename MaskTreeT>

bool initMask	(	const SdfGridT &	sdfGrid,
		const Grid< MaskTreeT > &	mask,
		bool	ignoreActiveTiles = false )

Initializer used for the extension of an existing signed distance field into the active values of an input mask of arbitrary value type.

Returns: True if the initialization succeeded.

Parameters

sdfGrid	Input signed distance field to be extended into the mask.
mask	Mask used to identify the topology of the output SDF. Note this mask is assume to overlap with the sdfGrid.
ignoreActiveTiles	If false, active tiles in the mask are treated as active voxels. Else they are ignored.

This, or any of ther other initialization methods, should be called before any call to sweep(). Failure to do so will throw a RuntimeError.

Warning: Note, if this method fails, i.e. returns false, a subsequent call to sweep will trow a RuntimeError. Instead call clear and try again.

◆ initSdf()

template<typename SdfGridT, typename ExtValueT>

bool initSdf	(	const SdfGridT &	sdfGrid,
		SdfValueT	isoValue,
		bool	isInputSdf )

Initializer for input grids that are either a signed distance field or a scalar fog volume.

Returns: True if the initialization succeeded.

Parameters

sdfGrid	Input scalar grid that represents an existing signed distance field or a fog volume (signified by isInputSdf).
isoValue	Iso-value to be used to define the Dirichlet boundary condition of the fast sweeping algorithm (typically 0 for sdfs and a positive value for fog volumes).
isInputSdf	Used to determine if sdfGrid is a sigend distance field (true) or a scalar fog volume (false).

This, or any of ther other initialization methods, should be called before any call to sweep(). Failure to do so will throw a RuntimeError.

Warning: Note, if this method fails, i.e. returns false, a subsequent call to sweep will trow a RuntimeError. Instead call clear and try again.

◆ isInputSdf()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

bool isInputSdf ( )

inline

Return whether the fast-sweeping input grid a signed distance function or not (fog).

◆ isValid()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

bool isValid ( ) const

inline

Return true if there are voxels and boundaries to solve for.

◆ operator=()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

FastSweeping & operator= ( const FastSweeping< SdfGridT, ExtValueT > & )

delete

Disallow copy assignment.

◆ sdfGrid()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

SdfGridT::Ptr sdfGrid ( )

inline

Returns a shared pointer to the signed distance field computed by this class.

Warning: This shared pointer might point to NULL if the grid has not been initialize (by one of the init methods) or computed (by the sweep method).

◆ sweep()

template<typename SdfGridT, typename ExtValueT>

void sweep	(	int	nIter = 1,
		bool	finalize = true )

Perform nIter iterations of the fast sweeping algorithm.

Parameters

nIter	Number of iterations of the fast sweeping algorithm. Each iteration performs 2^3 = 8 individual sweeps.
finalize	If true the (possibly asymmetric) inside and outside values of the resulting signed distance field are properly set. Unless you're an expert this should remain true!

Exceptions

RuntimeError if sweepingVoxelCount() or boundaryVoxelCount() return zero. This might happen if none of the initialization methods above were called or if that initialization failed.

◆ sweepDirection()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

FastSweepingDomain sweepDirection ( ) const

inline

Return whether the sweep update is in all direction (SWEEP_ALL), greater than isovalue (SWEEP_GREATER_THAN_ISOVALUE), or less than isovalue (SWEEP_LESS_THAN_ISOVALUE).

Note: SWEEP_GREATER_THAN_ISOVALUE and SWEEP_LESS_THAN_ISOVALUE modes are used in dilating the narrow-band of a levelset or in extending a field.

◆ sweepingVoxelCount()

template<typename SdfGridT, typename ExtValueT = typename SdfGridT::ValueType>

size_t sweepingVoxelCount ( ) const

inline

Return the number of voxels that will be solved for.

Classes

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ FastSweeping() [1/2]

◆ ~FastSweeping()

◆ FastSweeping() [2/2]

Member Function Documentation

◆ boundaryVoxelCount()

◆ clear()

◆ extGrid()

◆ extGridInput()

◆ initDilate()

◆ initExt() [1/2]

◆ initExt() [2/2]

◆ initMask()

◆ initSdf()

◆ isInputSdf()

◆ isValid()

◆ operator=()

◆ sdfGrid()

◆ sweep()

◆ sweepDirection()

◆ sweepingVoxelCount()