Point Cloud Library (PCL)
1.14.1-dev
|
VoxelGrid assembles a local 3D grid over a given PointCloud, and downsamples + filters the data. More...
#include <pcl/filters/voxel_grid.h>
Public Types | |
using | Ptr = shared_ptr< VoxelGrid< PointT > > |
using | ConstPtr = shared_ptr< const VoxelGrid< PointT > > |
Public Types inherited from pcl::Filter< PointT > | |
using | Ptr = shared_ptr< Filter< PointT > > |
using | ConstPtr = shared_ptr< const Filter< PointT > > |
using | PointCloud = pcl::PointCloud< PointT > |
using | PointCloudPtr = typename PointCloud::Ptr |
using | PointCloudConstPtr = typename PointCloud::ConstPtr |
Public Types inherited from pcl::PCLBase< PointT > | |
using | PointCloud = pcl::PointCloud< PointT > |
using | PointCloudPtr = typename PointCloud::Ptr |
using | PointCloudConstPtr = typename PointCloud::ConstPtr |
using | PointIndicesPtr = PointIndices::Ptr |
using | PointIndicesConstPtr = PointIndices::ConstPtr |
Public Member Functions | |
PCL_MAKE_ALIGNED_OPERATOR_NEW | VoxelGrid () |
Empty constructor. More... | |
~VoxelGrid () override=default | |
Destructor. More... | |
void | setLeafSize (const Eigen::Vector4f &leaf_size) |
Set the voxel grid leaf size. More... | |
void | setLeafSize (float lx, float ly, float lz) |
Set the voxel grid leaf size. More... | |
Eigen::Vector3f | getLeafSize () const |
Get the voxel grid leaf size. More... | |
void | setDownsampleAllData (bool downsample) |
Set to true if all fields need to be downsampled, or false if just XYZ. More... | |
bool | getDownsampleAllData () const |
Get the state of the internal downsampling parameter (true if all fields need to be downsampled, false if just XYZ). More... | |
void | setMinimumPointsNumberPerVoxel (unsigned int min_points_per_voxel) |
Set the minimum number of points required for a voxel to be used. More... | |
unsigned int | getMinimumPointsNumberPerVoxel () const |
Return the minimum number of points required for a voxel to be used. More... | |
void | setSaveLeafLayout (bool save_leaf_layout) |
Set to true if leaf layout information needs to be saved for later access. More... | |
bool | getSaveLeafLayout () const |
Returns true if leaf layout information will to be saved for later access. More... | |
Eigen::Vector3i | getMinBoxCoordinates () const |
Get the minimum coordinates of the bounding box (after filtering is performed). More... | |
Eigen::Vector3i | getMaxBoxCoordinates () const |
Get the minimum coordinates of the bounding box (after filtering is performed). More... | |
Eigen::Vector3i | getNrDivisions () const |
Get the number of divisions along all 3 axes (after filtering is performed). More... | |
Eigen::Vector3i | getDivisionMultiplier () const |
Get the multipliers to be applied to the grid coordinates in order to find the centroid index (after filtering is performed). More... | |
int | getCentroidIndex (const PointT &p) const |
Returns the index in the resulting downsampled cloud of the specified point. More... | |
std::vector< int > | getNeighborCentroidIndices (const PointT &reference_point, const Eigen::MatrixXi &relative_coordinates) const |
Returns the indices in the resulting downsampled cloud of the points at the specified grid coordinates, relative to the grid coordinates of the specified point (or -1 if the cell was empty/out of bounds). More... | |
std::vector< int > | getLeafLayout () const |
Returns the layout of the leafs for fast access to cells relative to current position. More... | |
Eigen::Vector3i | getGridCoordinates (float x, float y, float z) const |
Returns the corresponding (i,j,k) coordinates in the grid of point (x,y,z). More... | |
int | getCentroidIndexAt (const Eigen::Vector3i &ijk) const |
Returns the index in the downsampled cloud corresponding to a given set of coordinates. More... | |
void | setFilterFieldName (const std::string &field_name) |
Provide the name of the field to be used for filtering data. More... | |
std::string const | getFilterFieldName () const |
Get the name of the field used for filtering. More... | |
void | setFilterLimits (const double &limit_min, const double &limit_max) |
Set the field filter limits. More... | |
void | getFilterLimits (double &limit_min, double &limit_max) const |
Get the field filter limits (min/max) set by the user. More... | |
void | setFilterLimitsNegative (const bool limit_negative) |
Set to true if we want to return the data outside the interval specified by setFilterLimits (min, max). More... | |
void | getFilterLimitsNegative (bool &limit_negative) const |
Get whether the data outside the interval (min/max) is to be returned (true) or inside (false). More... | |
bool | getFilterLimitsNegative () const |
Get whether the data outside the interval (min/max) is to be returned (true) or inside (false). More... | |
Public Member Functions inherited from pcl::Filter< PointT > | |
Filter (bool extract_removed_indices=false) | |
Empty constructor. More... | |
IndicesConstPtr const | getRemovedIndices () const |
Get the point indices being removed. More... | |
void | getRemovedIndices (PointIndices &pi) |
Get the point indices being removed. More... | |
void | filter (PointCloud &output) |
Calls the filtering method and returns the filtered dataset in output. More... | |
Public Member Functions inherited from pcl::PCLBase< PointT > | |
PCLBase () | |
Empty constructor. More... | |
PCLBase (const PCLBase &base) | |
Copy constructor. More... | |
virtual | ~PCLBase ()=default |
Destructor. More... | |
virtual void | setInputCloud (const PointCloudConstPtr &cloud) |
Provide a pointer to the input dataset. More... | |
PointCloudConstPtr const | getInputCloud () const |
Get a pointer to the input point cloud dataset. More... | |
virtual void | setIndices (const IndicesPtr &indices) |
Provide a pointer to the vector of indices that represents the input data. More... | |
virtual void | setIndices (const IndicesConstPtr &indices) |
Provide a pointer to the vector of indices that represents the input data. More... | |
virtual void | setIndices (const PointIndicesConstPtr &indices) |
Provide a pointer to the vector of indices that represents the input data. More... | |
virtual void | setIndices (std::size_t row_start, std::size_t col_start, std::size_t nb_rows, std::size_t nb_cols) |
Set the indices for the points laying within an interest region of the point cloud. More... | |
IndicesPtr | getIndices () |
Get a pointer to the vector of indices used. More... | |
IndicesConstPtr const | getIndices () const |
Get a pointer to the vector of indices used. More... | |
const PointT & | operator[] (std::size_t pos) const |
Override PointCloud operator[] to shorten code. More... | |
Protected Types | |
using | PointCloud = typename Filter< PointT >::PointCloud |
using | PointCloudPtr = typename PointCloud::Ptr |
using | PointCloudConstPtr = typename PointCloud::ConstPtr |
using | FieldList = typename pcl::traits::fieldList< PointT >::type |
Protected Member Functions | |
void | applyFilter (PointCloud &output) override |
Downsample a Point Cloud using a voxelized grid approach. More... | |
Protected Member Functions inherited from pcl::Filter< PointT > | |
const std::string & | getClassName () const |
Get a string representation of the name of this class. More... | |
Protected Member Functions inherited from pcl::PCLBase< PointT > | |
bool | initCompute () |
This method should get called before starting the actual computation. More... | |
bool | deinitCompute () |
This method should get called after finishing the actual computation. More... | |
Protected Attributes | |
Eigen::Vector4f | leaf_size_ |
The size of a leaf. More... | |
Eigen::Array4f | inverse_leaf_size_ |
Internal leaf sizes stored as 1/leaf_size_ for efficiency reasons. More... | |
bool | downsample_all_data_ {true} |
Set to true if all fields need to be downsampled, or false if just XYZ. More... | |
bool | save_leaf_layout_ {false} |
Set to true if leaf layout information needs to be saved in leaf_layout_. More... | |
std::vector< int > | leaf_layout_ |
The leaf layout information for fast access to cells relative to current position. More... | |
Eigen::Vector4i | min_b_ |
The minimum and maximum bin coordinates, the number of divisions, and the division multiplier. More... | |
Eigen::Vector4i | max_b_ |
Eigen::Vector4i | div_b_ |
Eigen::Vector4i | divb_mul_ |
std::string | filter_field_name_ |
The desired user filter field name. More... | |
double | filter_limit_min_ {std::numeric_limits<float>::lowest()} |
The minimum allowed filter value a point will be considered from. More... | |
double | filter_limit_max_ {std::numeric_limits<float>::max()} |
The maximum allowed filter value a point will be considered from. More... | |
bool | filter_limit_negative_ {false} |
Set to true if we want to return the data outside (filter_limit_min_;filter_limit_max_). More... | |
unsigned int | min_points_per_voxel_ {0} |
Minimum number of points per voxel for the centroid to be computed. More... | |
Protected Attributes inherited from pcl::Filter< PointT > | |
IndicesPtr | removed_indices_ |
Indices of the points that are removed. More... | |
std::string | filter_name_ |
The filter name. More... | |
bool | extract_removed_indices_ |
Set to true if we want to return the indices of the removed points. More... | |
Protected Attributes inherited from pcl::PCLBase< PointT > | |
PointCloudConstPtr | input_ |
The input point cloud dataset. More... | |
IndicesPtr | indices_ |
A pointer to the vector of point indices to use. More... | |
bool | use_indices_ |
Set to true if point indices are used. More... | |
bool | fake_indices_ |
If no set of indices are given, we construct a set of fake indices that mimic the input PointCloud. More... | |
VoxelGrid assembles a local 3D grid over a given PointCloud, and downsamples + filters the data.
The VoxelGrid class creates a 3D voxel grid (think about a voxel grid as a set of tiny 3D boxes in space) over the input point cloud data. Then, in each voxel (i.e., 3D box), all the points present will be approximated (i.e., downsampled) with their centroid. This approach is a bit slower than approximating them with the center of the voxel, but it represents the underlying surface more accurately.
Definition at line 209 of file voxel_grid.h.
using pcl::VoxelGrid< PointT >::ConstPtr = shared_ptr<const VoxelGrid<PointT> > |
Definition at line 224 of file voxel_grid.h.
|
protected |
Definition at line 515 of file voxel_grid.h.
|
protected |
Definition at line 217 of file voxel_grid.h.
|
protected |
Definition at line 219 of file voxel_grid.h.
|
protected |
Definition at line 218 of file voxel_grid.h.
using pcl::VoxelGrid< PointT >::Ptr = shared_ptr<VoxelGrid<PointT> > |
Definition at line 223 of file voxel_grid.h.
|
inline |
Empty constructor.
Definition at line 229 of file voxel_grid.h.
References pcl::Filter< PointT >::filter_name_.
|
overridedefault |
Destructor.
|
overrideprotectedvirtual |
Downsample a Point Cloud using a voxelized grid approach.
[out] | output | the resultant point cloud message |
Implements pcl::Filter< PointT >.
Reimplemented in pcl::VoxelGridCovariance< PointT >, and pcl::VoxelGridCovariance< PointTarget >.
Definition at line 216 of file voxel_grid.hpp.
References pcl::CentroidPoint< PointT >::add(), pcl::PointCloud< PointT >::clear(), pcl::CentroidPoint< PointT >::get(), pcl::PointCloud< PointT >::height, pcl::internal::cloud_point_index_idx::idx, pcl::PointCloud< PointT >::is_dense, pcl::isXYZFinite(), pcl::PointCloud< PointT >::resize(), pcl::PointCloud< PointT >::size(), and pcl::PointCloud< PointT >::width.
|
inline |
Returns the index in the resulting downsampled cloud of the specified point.
[in] | p | the point to get the index at |
Definition at line 343 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::divb_mul_, pcl::VoxelGrid< PointT >::inverse_leaf_size_, pcl::VoxelGrid< PointT >::leaf_layout_, and pcl::VoxelGrid< PointT >::min_b_.
Referenced by pcl::ism::ImplicitShapeModelEstimation< FeatureSize, PointT, NormalT >::simplifyCloud().
|
inline |
Returns the index in the downsampled cloud corresponding to a given set of coordinates.
[in] | ijk | the coordinates (i,j,k) in the grid (-1 if empty) |
Definition at line 400 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::divb_mul_, pcl::VoxelGrid< PointT >::leaf_layout_, and pcl::VoxelGrid< PointT >::min_b_.
|
inline |
Get the multipliers to be applied to the grid coordinates in order to find the centroid index (after filtering is performed).
Definition at line 332 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::divb_mul_.
|
inline |
Get the state of the internal downsampling parameter (true if all fields need to be downsampled, false if just XYZ).
Definition at line 287 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::downsample_all_data_.
|
inline |
Get the name of the field used for filtering.
Definition at line 424 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::filter_field_name_.
|
inline |
Get the field filter limits (min/max) set by the user.
The default values are std::numeric_limits<float>::lowest(), std::numeric_limits<float>::max().
[out] | limit_min | the minimum allowed field value |
[out] | limit_max | the maximum allowed field value |
Definition at line 446 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::filter_limit_max_, and pcl::VoxelGrid< PointT >::filter_limit_min_.
|
inline |
Get whether the data outside the interval (min/max) is to be returned (true) or inside (false).
Definition at line 476 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::filter_limit_negative_.
|
inline |
Get whether the data outside the interval (min/max) is to be returned (true) or inside (false).
[out] | limit_negative | true if data outside the interval [min; max] is to be returned, false otherwise |
Definition at line 467 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::filter_limit_negative_.
|
inline |
Returns the corresponding (i,j,k) coordinates in the grid of point (x,y,z).
[in] | x | the X point coordinate to get the (i, j, k) index at |
[in] | y | the Y point coordinate to get the (i, j, k) index at |
[in] | z | the Z point coordinate to get the (i, j, k) index at |
Definition at line 389 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::inverse_leaf_size_.
|
inline |
Returns the layout of the leafs for fast access to cells relative to current position.
Definition at line 381 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::leaf_layout_.
|
inline |
Get the voxel grid leaf size.
Definition at line 275 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::leaf_size_.
|
inline |
Get the minimum coordinates of the bounding box (after filtering is performed).
Definition at line 320 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::max_b_.
|
inline |
Get the minimum coordinates of the bounding box (after filtering is performed).
Definition at line 314 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::min_b_.
|
inline |
Return the minimum number of points required for a voxel to be used.
Definition at line 298 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::min_points_per_voxel_.
|
inline |
Returns the indices in the resulting downsampled cloud of the points at the specified grid coordinates, relative to the grid coordinates of the specified point (or -1 if the cell was empty/out of bounds).
[in] | reference_point | the coordinates of the reference point (corresponding cell is allowed to be empty/out of bounds) |
[in] | relative_coordinates | matrix with the columns being the coordinates of the requested cells, relative to the reference point's cell |
Definition at line 357 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::divb_mul_, pcl::VoxelGrid< PointT >::inverse_leaf_size_, pcl::VoxelGrid< PointT >::leaf_layout_, pcl::VoxelGrid< PointT >::max_b_, and pcl::VoxelGrid< PointT >::min_b_.
Referenced by pcl::GRSDEstimation< PointInT, PointNT, PointOutT >::computeFeature().
|
inline |
Get the number of divisions along all 3 axes (after filtering is performed).
Definition at line 326 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::div_b_.
|
inline |
Returns true if leaf layout information will to be saved for later access.
Definition at line 308 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::save_leaf_layout_.
|
inline |
Set to true if all fields need to be downsampled, or false if just XYZ.
[in] | downsample | the new value (true/false) |
Definition at line 281 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::downsample_all_data_.
Referenced by pcl::CrfSegmentation< PointT >::createVoxelGrid(), and pcl::HypothesisVerification< ModelT, SceneT >::setSceneCloud().
|
inline |
Provide the name of the field to be used for filtering data.
In conjunction with setFilterLimits, points having values outside this interval will be discarded.
[in] | field_name | the name of the field that contains values used for filtering |
Definition at line 417 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::filter_field_name_.
Referenced by pcl::people::GroundBasedPeopleDetectionApp< PointT >::filter().
|
inline |
Set the field filter limits.
All points having field values outside this interval will be discarded.
[in] | limit_min | the minimum allowed field value |
[in] | limit_max | the maximum allowed field value |
Definition at line 434 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::filter_limit_max_, and pcl::VoxelGrid< PointT >::filter_limit_min_.
Referenced by pcl::people::GroundBasedPeopleDetectionApp< PointT >::filter().
|
inline |
Set to true if we want to return the data outside the interval specified by setFilterLimits (min, max).
Default: false.
[in] | limit_negative | return data inside the interval (false) or outside (true) |
Definition at line 457 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::filter_limit_negative_.
|
inline |
Set the voxel grid leaf size.
[in] | leaf_size | the voxel grid leaf size |
Definition at line 247 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::inverse_leaf_size_, and pcl::VoxelGrid< PointT >::leaf_size_.
Referenced by pcl::GRSDEstimation< PointInT, PointNT, PointOutT >::computeFeature(), pcl::CrfSegmentation< PointT >::createVoxelGrid(), pcl::SIFTKeypoint< PointInT, PointOutT >::detectKeypoints(), pcl::people::GroundBasedPeopleDetectionApp< PointT >::filter(), pcl::NormalDistributionsTransform< PointSource, PointTarget, Scalar >::init(), pcl::HypothesisVerification< ModelT, SceneT >::setSceneCloud(), and pcl::ism::ImplicitShapeModelEstimation< FeatureSize, PointT, NormalT >::simplifyCloud().
|
inline |
Set the voxel grid leaf size.
[in] | lx | the leaf size for X |
[in] | ly | the leaf size for Y |
[in] | lz | the leaf size for Z |
Definition at line 263 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::inverse_leaf_size_, and pcl::VoxelGrid< PointT >::leaf_size_.
|
inline |
Set the minimum number of points required for a voxel to be used.
[in] | min_points_per_voxel | the minimum number of points for required for a voxel to be used |
Definition at line 293 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::min_points_per_voxel_.
|
inline |
Set to true if leaf layout information needs to be saved for later access.
[in] | save_leaf_layout | the new value (true/false) |
Definition at line 304 of file voxel_grid.h.
References pcl::VoxelGrid< PointT >::save_leaf_layout_.
Referenced by pcl::GRSDEstimation< PointInT, PointNT, PointOutT >::computeFeature(), pcl::ism::ImplicitShapeModelEstimation< FeatureSize, PointT, NormalT >::simplifyCloud(), and pcl::VoxelGridOcclusionEstimation< PointT >::VoxelGridOcclusionEstimation().
|
protected |
Definition at line 498 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getNrDivisions().
|
protected |
Definition at line 498 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getCentroidIndex(), pcl::VoxelGrid< PointT >::getCentroidIndexAt(), pcl::VoxelGrid< PointT >::getDivisionMultiplier(), pcl::VoxelGridCovariance< PointT >::getLeaf(), and pcl::VoxelGrid< PointT >::getNeighborCentroidIndices().
|
protected |
Set to true if all fields need to be downsampled, or false if just XYZ.
Definition at line 489 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getDownsampleAllData(), pcl::VoxelGrid< PointT >::setDownsampleAllData(), and pcl::VoxelGridCovariance< PointT >::VoxelGridCovariance().
|
protected |
The desired user filter field name.
Definition at line 501 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getFilterFieldName(), and pcl::VoxelGrid< PointT >::setFilterFieldName().
|
protected |
The maximum allowed filter value a point will be considered from.
Definition at line 507 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getFilterLimits(), and pcl::VoxelGrid< PointT >::setFilterLimits().
|
protected |
The minimum allowed filter value a point will be considered from.
Definition at line 504 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getFilterLimits(), and pcl::VoxelGrid< PointT >::setFilterLimits().
|
protected |
Set to true if we want to return the data outside (filter_limit_min_;filter_limit_max_).
Default: false.
Definition at line 510 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getFilterLimitsNegative(), and pcl::VoxelGrid< PointT >::setFilterLimitsNegative().
|
protected |
Internal leaf sizes stored as 1/leaf_size_ for efficiency reasons.
Definition at line 486 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getCentroidIndex(), pcl::VoxelGrid< PointT >::getGridCoordinates(), pcl::VoxelGridOcclusionEstimation< PointT >::getGridCoordinatesRound(), pcl::VoxelGridCovariance< PointT >::getLeaf(), pcl::VoxelGrid< PointT >::getNeighborCentroidIndices(), and pcl::VoxelGrid< PointT >::setLeafSize().
|
protected |
The leaf layout information for fast access to cells relative to current position.
Definition at line 495 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getCentroidIndex(), pcl::VoxelGrid< PointT >::getCentroidIndexAt(), pcl::VoxelGrid< PointT >::getLeafLayout(), and pcl::VoxelGrid< PointT >::getNeighborCentroidIndices().
|
protected |
The size of a leaf.
Definition at line 483 of file voxel_grid.h.
Referenced by pcl::VoxelGridOcclusionEstimation< PointT >::getCentroidCoordinate(), pcl::VoxelGrid< PointT >::getLeafSize(), pcl::VoxelGrid< PointT >::setLeafSize(), and pcl::VoxelGridCovariance< PointT >::VoxelGridCovariance().
|
protected |
Definition at line 498 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getMaxBoxCoordinates(), pcl::VoxelGrid< PointT >::getNeighborCentroidIndices(), and pcl::VoxelGridCovariance< PointT >::VoxelGridCovariance().
|
protected |
The minimum and maximum bin coordinates, the number of divisions, and the division multiplier.
Definition at line 498 of file voxel_grid.h.
Referenced by pcl::VoxelGridOcclusionEstimation< PointT >::getCentroidCoordinate(), pcl::VoxelGrid< PointT >::getCentroidIndex(), pcl::VoxelGrid< PointT >::getCentroidIndexAt(), pcl::VoxelGridCovariance< PointT >::getLeaf(), pcl::VoxelGrid< PointT >::getMinBoxCoordinates(), pcl::VoxelGrid< PointT >::getNeighborCentroidIndices(), and pcl::VoxelGridCovariance< PointT >::VoxelGridCovariance().
|
protected |
Minimum number of points per voxel for the centroid to be computed.
Definition at line 513 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getMinimumPointsNumberPerVoxel(), and pcl::VoxelGrid< PointT >::setMinimumPointsNumberPerVoxel().
|
protected |
Set to true if leaf layout information needs to be saved in leaf_layout_.
Definition at line 492 of file voxel_grid.h.
Referenced by pcl::VoxelGrid< PointT >::getSaveLeafLayout(), pcl::VoxelGrid< PointT >::setSaveLeafLayout(), and pcl::VoxelGridCovariance< PointT >::VoxelGridCovariance().