A DistanceField implementation that uses a vector propagation method. Distances propagate outward from occupied cells, or inwards from unoccupied cells if negative distances are to be computed, which is optional. Outward and inward propagation only occur to a desired maximum distance  cells that are more than this maximum distance from the nearest cell will have maximum distance measurements. More...
#include <propagation_distance_field.h>
Public Member Functions  
void  addPointsToField (const EigenSTL::vector_Vector3d &points) override 
Add a set of obstacle points to the distance field, updating distance values accordingly. The distance field may already contain obstacle cells. More...  
const PropDistanceFieldVoxel &  getCell (int x, int y, int z) const 
Gets full cell data given an index. More...  
double  getDistance (double x, double y, double z) const override 
Get the distance value associated with the cell indicated by the world coordinate. If the cell is invalid, max_distance will be returned. If running without negative distances, all obstacle cells will have zero distance. If running with negative distances, the distance will be between max_distance and max_distance, with no values having a 0 distance. More...  
double  getDistance (int x, int y, int z) const override 
Get the distance value associated with the cell indicated by the index coordinates. If the cell is invalid, max_distance will be returned. If running without negative distances, all obstacle cells will have zero distance. If running with negative distances, the distance will be between max_distance and max_distance, with no values having a 0 distance. More...  
int  getMaximumDistanceSquared () const 
Gets the maximum distance squared value. More...  
const PropDistanceFieldVoxel *  getNearestCell (int x, int y, int z, double &dist, Eigen::Vector3i &pos) const 
Gets nearest surface cell and returns distance to it. More...  
double  getUninitializedDistance () const override 
Gets a distance value for an invalid cell. More...  
int  getXNumCells () const override 
Gets the number of cells along the X axis. More...  
int  getYNumCells () const override 
Gets the number of cells along the Y axis. More...  
int  getZNumCells () const override 
Gets the number of cells along the Z axis. More...  
bool  gridToWorld (int x, int y, int z, double &world_x, double &world_y, double &world_z) const override 
Converts from an set of integer indices to a world location given the origin and resolution parameters. More...  
bool  isCellValid (int x, int y, int z) const override 
Determines whether or not the cell associated with the supplied indices is valid for this distance field. More...  
PropagationDistanceField (double size_x, double size_y, double size_z, double resolution, double origin_x, double origin_y, double origin_z, double max_distance, bool propagate_negative_distances=false)  
Constructor that initializes entire distance field to empty  all cells will be assigned maximum distance values. All units are arbitrary but are assumed for documentation purposes to represent meters. More...  
PropagationDistanceField (const octomap::OcTree &octree, const octomap::point3d &bbx_min, const octomap::point3d &bbx_max, double max_distance, bool propagate_negative_distances=false)  
Constructor based on an OcTree and bounding box information. A distance field will be constructed with dimensions based on the supplied bounding box at the resolution of the OcTree. All octree obstacle cells will be added to the resulting distance field using the DistanceField::addOcTreeToField function. More...  
PropagationDistanceField (std::istream &stream, double max_distance, bool propagate_negative_distances=false)  
Constructor that takes an istream and reads the contents of a saved distance field, adding all obstacle points and running propagation given the arguments for max_distance and propagate_negative_distances. Calls the function readFromStream. More...  
bool  readFromStream (std::istream &stream) override 
Reads, parameterizes, and populates the distance field based on the supplied stream. More...  
void  removePointsFromField (const EigenSTL::vector_Vector3d &points) override 
Remove a set of obstacle points from the distance field, updating distance values accordingly. More...  
void  reset () override 
Resets the entire distance field to max_distance for positive values and zero for negative values. More...  
void  updatePointsInField (const EigenSTL::vector_Vector3d &old_points, const EigenSTL::vector_Vector3d &new_points) override 
This function will remove any obstacle points that are in the old point set but not the new point set, and add any obstacle points that are in the new block set but not the old block set. Any points that are in both sets are left unchanged. For more information see DistanceField::updatePointsInField. More...  
bool  worldToGrid (double world_x, double world_y, double world_z, int &x, int &y, int &z) const override 
Converts from a world location to a set of integer indices. Should return false if the world location is not valid in the distance field, and should populate the index values in either case. More...  
bool  writeToStream (std::ostream &stream) const override 
Writes the contents of the distance field to the supplied stream. More...  
~PropagationDistanceField () override  
Empty destructor. More...  
Public Member Functions inherited from distance_field::DistanceField  
void  addOcTreeToField (const octomap::OcTree *octree) 
Adds an octree to the distance field. Cells that are occupied in the octree that lie within the voxel grid are added to the distance field. The octree can represent either a larger or smaller volume than the distance field. If the resolution of the octree is less than or equal to the resolution of the distance field then the center of each leaf cell of the octree will be added to the distance field. If the resolution of the octree is greater than a 3D volume of the correct resolution will be added for each occupied leaf node. More...  
void  addShapeToField (const shapes::Shape *shape, const Eigen::Isometry3d &pose) 
Adds the set of points corresponding to the shape at the given pose as obstacle points into the distance field. If the shape is an OcTree, the pose information is ignored and the OcTree is passed to the addOcTreeToField function. More...  
void  addShapeToField (const shapes::Shape *shape, const geometry_msgs::Pose &pose) 
DistanceField (double size_x, double size_y, double size_z, double resolution, double origin_x, double origin_y, double origin_z)  
Constructor, where units are arbitrary but are assumed to be meters. More...  
double  getDistanceGradient (double x, double y, double z, double &gradient_x, double &gradient_y, double &gradient_z, bool &in_bounds) const 
Gets not only the distance to the nearest cell but the gradient direction. The gradient is computed as a function of the distances of nearby cells. An uninitialized distance is returned if the cell is not valid for gradient production purposes. The gradient is pointing out of the obstacle  thus to recover the closest obstacle point, the normalized gradient value is multiplied by the distance and subtracted from the cell's location, as shown below. More...  
void  getGradientMarkers (double min_radius, double max_radius, const std::string &frame_id, const ros::Time &stamp, visualization_msgs::MarkerArray &marker_array) const 
Populates the supplied marker array with a series of arrows representing gradients of cells that are within the supplied range in terms of distance. The markers will be visualization_msgs::Marker::ARROW in the namespace "distance_field_gradient". More...  
void  getIsoSurfaceMarkers (double min_distance, double max_distance, const std::string &frame_id, const ros::Time stamp, visualization_msgs::Marker &marker) const 
Get an isosurface for visualization in rviz. The isosurface shows every cell that has a distance in a given range in the distance field. The cells are added as a visualization_msgs::Marker::CUBE_LIST in the namespace "distance_field". More...  
double  getOriginX () const 
Gets the origin (minimum value) along the X dimension. More...  
double  getOriginY () const 
Gets the origin (minimum value) along the Y dimension. More...  
double  getOriginZ () const 
Gets the origin (minimum value) along the Z dimension. More...  
void  getPlaneMarkers (PlaneVisualizationType type, double length, double width, double height, const Eigen::Vector3d &origin, const std::string &frame_id, const ros::Time stamp, visualization_msgs::Marker &marker) const 
Populates a marker with a slice of the distance field in a particular plane. All cells in the plane will be added to the field, with colors associated with their distance. More...  
void  getProjectionPlanes (const std::string &frame_id, const ros::Time &stamp, double max_distance, visualization_msgs::Marker &marker) const 
A function that populates the marker with three planes  one each along the XY, XZ, and YZ axes. For each of the planes, any column on that plane will be marked according to the minimum distance along that column. More...  
double  getResolution () const 
Gets the resolution of the distance field in meters. More...  
bool  getShapePoints (const shapes::Shape *shape, const Eigen::Isometry3d &pose, EigenSTL::vector_Vector3d *points) 
Get the points associated with a shape. This is mainly used when the external application needs to cache points. More...  
double  getSizeX () const 
Gets the distance field size along the X dimension in meters. More...  
double  getSizeY () const 
Gets the distance field size along the Y dimension in meters. More...  
double  getSizeZ () const 
Gets the distance field size along the Z dimension in meters. More...  
void  moveShapeInField (const shapes::Shape *shape, const Eigen::Isometry3d &old_pose, const Eigen::Isometry3d &new_pose) 
Moves the shape in the distance field from the old pose to the new pose, removing points that are no longer obstacle points, and adding points that are now obstacle points at the new pose. This function will discretize both shapes, and call the updatePointsInField function on the old and new point sets. More...  
void  moveShapeInField (const shapes::Shape *shape, const geometry_msgs::Pose &old_pose, const geometry_msgs::Pose &new_pose) 
void  removeShapeFromField (const shapes::Shape *shape, const Eigen::Isometry3d &pose) 
All points corresponding to the shape are removed from the distance field. More...  
void  removeShapeFromField (const shapes::Shape *shape, const geometry_msgs::Pose &pose) 
virtual  ~DistanceField () 
Private Types  
typedef std::set< Eigen::Vector3i, compareEigen_Vector3i, Eigen::aligned_allocator< Eigen::Vector3i > >  VoxelSet 
Private Member Functions  
void  addNewObstacleVoxels (const EigenSTL::vector_Vector3i &voxel_points) 
Adds a valid set of integer points to the voxel grid. More...  
int  getDirectionNumber (int dx, int dy, int dz) const 
Helper function to get a single number in a 27 connected 3D voxel grid given dx, dy, and dz values. More...  
virtual double  getDistance (const PropDistanceFieldVoxel &object) const 
Determines distance based on actual voxel data. More...  
Eigen::Vector3i  getLocationDifference (int directionNumber) const 
Helper function that gets change values given single number representing update direction. More...  
void  initialize () 
Initializes the field, resetting the voxel grid and building a sqrt lookup table for efficiency based on max_distance_. More...  
void  initNeighborhoods () 
Helper function for computing location and neighborhood information in 27 connected voxel grid. More...  
void  print (const VoxelSet &set) 
Debug function that prints all voxels in a set to ROS_DEBUG_NAMED. More...  
void  print (const EigenSTL::vector_Vector3d &points) 
Debug function that prints all points in a vector to ROS_DEBUG_NAMED. More...  
void  propagateNegative () 
Propagates inward to a maximum distance given the contents of the negative_bucket_queue_, and clears the negative_bucket_queue_. More...  
void  propagatePositive () 
Propagates outward to the maximum distance given the contents of the bucket_queue_, and clears the bucket_queue_. More...  
void  removeObstacleVoxels (const EigenSTL::vector_Vector3i &voxel_points) 
Removes a valid set of integer points from the voxel grid. More...  
Private Attributes  
std::vector< EigenSTL::vector_Vector3i >  bucket_queue_ 
Structure used to hold propagation frontier. More...  
EigenSTL::vector_Vector3i  direction_number_to_direction_ 
Holds conversion from direction number to integer changes. More...  
double  max_distance_ 
Holds maximum distance. More...  
int  max_distance_sq_ 
Holds maximum distance squared in cells. More...  
std::vector< EigenSTL::vector_Vector3i >  negative_bucket_queue_ 
Data member that holds points from which to propagate in the negative, where each vector holds points that are a particular integer distance from the closest unoccupied points. More...  
std::vector< std::vector< EigenSTL::vector_Vector3i > >  neighborhoods_ 
Holds information on neighbor direction, with 27 different directions. Shows where to propagate given an integer distance and an update direction. More...  
bool  propagate_negative_ 
Whether or not to propagate negative distances. More...  
std::vector< double >  sqrt_table_ 
Precomputed square root table for faster distance lookups. More...  
VoxelGrid< PropDistanceFieldVoxel >::Ptr  voxel_grid_ 
Actual container for distance data. More...  
Additional Inherited Members  
Protected Member Functions inherited from distance_field::DistanceField  
void  getOcTreePoints (const octomap::OcTree *octree, EigenSTL::vector_Vector3d *points) 
Get the points associated with an octree. More...  
void  setPoint (int xCell, int yCell, int zCell, double dist, geometry_msgs::Point &point, std_msgs::ColorRGBA &color, double max_distance) const 
Helper function that sets the point value and color given the distance. More...  
Protected Attributes inherited from distance_field::DistanceField  
int  inv_twice_resolution_ 
Computed value 1.0/(2.0*resolution_) More...  
double  origin_x_ 
X origin of the distance field. More...  
double  origin_y_ 
Y origin of the distance field. More...  
double  origin_z_ 
Z origin of the distance field. More...  
double  resolution_ 
Resolution of the distance field. More...  
double  size_x_ 
X size of the distance field. More...  
double  size_y_ 
Y size of the distance field. More...  
double  size_z_ 
Z size of the distance field. More...  
A DistanceField implementation that uses a vector propagation method. Distances propagate outward from occupied cells, or inwards from unoccupied cells if negative distances are to be computed, which is optional. Outward and inward propagation only occur to a desired maximum distance  cells that are more than this maximum distance from the nearest cell will have maximum distance measurements.
This class uses a VoxelGrid to hold all data. One important decision that must be made on construction is whether or not to create a signed version of the distance field. If the distance field is unsigned, it means that the minumum obstacle distance is 0, a value that will be assigned to all obstacle cells. Gradient queries for obstacle cells will not give useful information, as the gradient at an obstacle cell will point to the cell itself. If this behavior is acceptable, then the performance of this mode will be more efficient, as no propagation will occur for obstacle cells. The other option is to calculate signed distances. In this case, negative distances up to the maximum distance are calculated for obstacle volumes. This distance encodes the distance of an obstacle cell to the nearest unoccupied obstacle voxel. Furthmore, gradients pointing out of the volume will be produced. Depending on the data, calculating this data can significantly impact the time it takes to add and remove obstacle cells.
Definition at line 138 of file propagation_distance_field.h.

private 
Typedef for set of integer indices
Definition at line 451 of file propagation_distance_field.h.
distance_field::PropagationDistanceField::PropagationDistanceField  (  double  size_x, 
double  size_y,  
double  size_z,  
double  resolution,  
double  origin_x,  
double  origin_y,  
double  origin_z,  
double  max_distance,  
bool  propagate_negative_distances = false 

) 
Constructor that initializes entire distance field to empty  all cells will be assigned maximum distance values. All units are arbitrary but are assumed for documentation purposes to represent meters.
[in]  size_x  The X dimension in meters of the volume to represent 
[in]  size_y  The Y dimension in meters of the volume to represent 
[in]  size_z  The Z dimension in meters of the volume to represent 
[in]  resolution  The resolution in meters of the volume 
[in]  origin_x  The minimum X point of the volume 
[in]  origin_y  The minimum Y point of the volume 
[in]  origin_z  The minimum Z point of the volume 
[in]  max_distance  The maximum distance to which to propagate distance values. Cells that are greater than this distance will be assigned the maximum distance value. 
[in]  propagate_negative_distances  Whether or not to propagate negative distances. If false, no propagation occurs, and all obstacle cells will be assigned zero distance. See the PropagationDistanceField description for more information on the implications of this. 
Definition at line 46 of file propagation_distance_field.cpp.
distance_field::PropagationDistanceField::PropagationDistanceField  (  const octomap::OcTree &  octree, 
const octomap::point3d &  bbx_min,  
const octomap::point3d &  bbx_max,  
double  max_distance,  
bool  propagate_negative_distances = false 

) 
Constructor based on an OcTree and bounding box information. A distance field will be constructed with dimensions based on the supplied bounding box at the resolution of the OcTree. All octree obstacle cells will be added to the resulting distance field using the DistanceField::addOcTreeToField function.
[in]  octree  The OcTree from which to construct the distance field 
[in]  bbx_min  The minimum world coordinates of the bounding box 
[in]  bbx_max  The maximum world coordinates of the bounding box 
[in]  max_distance  The maximum distance to which to propagate distance values. Cells that are greater than this distance will be assigned the maximum distance value. 
[in]  propagate_negative_distances  Whether or not to propagate negative distances. If false, no propagation occurs, and all obstacle cells will be assigned zero distance. See the PropagationDistanceField description for more information on the implications of this. 
Definition at line 56 of file propagation_distance_field.cpp.
distance_field::PropagationDistanceField::PropagationDistanceField  (  std::istream &  stream, 
double  max_distance,  
bool  propagate_negative_distances = false 

) 
Constructor that takes an istream and reads the contents of a saved distance field, adding all obstacle points and running propagation given the arguments for max_distance and propagate_negative_distances. Calls the function readFromStream.
[in]  stream  The stream from which to read the data 
[in]  max_distance  The maximum distance to which to propagate distance values. Cells that are greater than this distance will be assigned the maximum distance value. 
[in]  propagate_negative_distances  Whether or not to propagate negative distances. If false, no propagation occurs, and all obstacle cells will be assigned zero distance. See the PropagationDistanceField description for more information on the implications of this. 
Definition at line 69 of file propagation_distance_field.cpp.

inlineoverride 
Empty destructor.
Definition at line 223 of file propagation_distance_field.h.

private 
Adds a valid set of integer points to the voxel grid.
voxel_points  Valid set of voxel points for addition 
Definition at line 221 of file propagation_distance_field.cpp.

overridevirtual 
Add a set of obstacle points to the distance field, updating distance values accordingly. The distance field may already contain obstacle cells.
The function first checks that each location represents a valid point  only valid points will be added. It takes the vector of valid points and performs positive propagation on them. If the class has been set up to propagate negative distance, those will also be propagated.
[in]  points  The set of obstacle points to add 
Implements distance_field::DistanceField.
Definition at line 177 of file propagation_distance_field.cpp.

inline 
Gets full cell data given an index.
x,y,z MUST be valid or data corruption (SEGFAULTS) will occur.
[in]  x  The integer X location 
[in]  y  The integer Y location 
[in]  z  The integer Z location 
Definition at line 389 of file propagation_distance_field.h.

private 
Helper function to get a single number in a 27 connected 3D voxel grid given dx, dy, and dz values.
dx  The change in the X direction 
dy  The change in the X direction 
dz  The change in the Z direction 
Definition at line 588 of file propagation_distance_field.cpp.

overridevirtual 
Get the distance value associated with the cell indicated by the world coordinate. If the cell is invalid, max_distance will be returned. If running without negative distances, all obstacle cells will have zero distance. If running with negative distances, the distance will be between max_distance and max_distance, with no values having a 0 distance.
[in]  x  The X location of the cell 
[in]  y  The X location of the cell 
[in]  z  The X location of the cell 
Implements distance_field::DistanceField.
Definition at line 598 of file propagation_distance_field.cpp.

overridevirtual 
Get the distance value associated with the cell indicated by the index coordinates. If the cell is invalid, max_distance will be returned. If running without negative distances, all obstacle cells will have zero distance. If running with negative distances, the distance will be between max_distance and max_distance, with no values having a 0 distance.
[in]  x  The integer X location 
[in]  y  The integer Y location 
[in]  z  The integer Z location 
Implements distance_field::DistanceField.
Definition at line 603 of file propagation_distance_field.cpp.

inlineprivatevirtual 
Determines distance based on actual voxel data.
object  Actual voxel data 
Definition at line 598 of file propagation_distance_field.h.

private 
Helper function that gets change values given single number representing update direction.
directionNumber  Direction number 026 
Definition at line 593 of file propagation_distance_field.cpp.

inline 
Gets the maximum distance squared value.
Produced by taking the ceiling of the maximum distance divided by the resolution, and then squaring that value.
Definition at line 444 of file propagation_distance_field.h.

inline 
Gets nearest surface cell and returns distance to it.
x,y,z MUST be valid or data corruption (SEGFAULTS) will occur.
[in]  x  The integer X location of the starting cell 
[in]  y  The integer Y location of the starting cell 
[in]  z  The integer Z location of the starting cell 
[out]  dist  if starting cell is inside, the negative distance to the nearest outside cell if starting cell is outside, the positive distance to the nearest inside cell if nearby cell is unknown, zero 
[out]  pos  the position of the nearest cell 
Definition at line 412 of file propagation_distance_field.h.

inlineoverridevirtual 
Gets a distance value for an invalid cell.
Implements distance_field::DistanceField.
Definition at line 373 of file propagation_distance_field.h.

overridevirtual 
Gets the number of cells along the X axis.
Implements distance_field::DistanceField.
Definition at line 613 of file propagation_distance_field.cpp.

overridevirtual 
Gets the number of cells along the Y axis.
Implements distance_field::DistanceField.
Definition at line 618 of file propagation_distance_field.cpp.

overridevirtual 
Gets the number of cells along the Z axis.
Implements distance_field::DistanceField.
Definition at line 623 of file propagation_distance_field.cpp.

overridevirtual 
Converts from an set of integer indices to a world location given the origin and resolution parameters.
[in]  x  The integer X location 
[in]  y  The integer Y location 
[in]  z  The integer Z location 
[out]  world_x  The computed world X location 
[out]  world_y  The computed world X location 
[out]  world_z  The computed world X location 
Implements distance_field::DistanceField.
Definition at line 628 of file propagation_distance_field.cpp.

private 
Initializes the field, resetting the voxel grid and building a sqrt lookup table for efficiency based on max_distance_.
Definition at line 76 of file propagation_distance_field.cpp.

private 
Helper function for computing location and neighborhood information in 27 connected voxel grid.
Definition at line 530 of file propagation_distance_field.cpp.

overridevirtual 
Determines whether or not the cell associated with the supplied indices is valid for this distance field.
[in]  x  The X index of the cell 
[in]  y  The Y index of the cell 
[in]  z  The Z index of the cell 
Implements distance_field::DistanceField.
Definition at line 608 of file propagation_distance_field.cpp.

private 
Debug function that prints all voxels in a set to ROS_DEBUG_NAMED.
set  Voxel set to print 
Definition at line 95 of file propagation_distance_field.cpp.

private 
Debug function that prints all points in a vector to ROS_DEBUG_NAMED.
points  Points to print 
Definition at line 107 of file propagation_distance_field.cpp.

private 
Propagates inward to a maximum distance given the contents of the negative_bucket_queue_, and clears the negative_bucket_queue_.
Definition at line 448 of file propagation_distance_field.cpp.

private 
Propagates outward to the maximum distance given the contents of the bucket_queue_, and clears the bucket_queue_.
Definition at line 390 of file propagation_distance_field.cpp.

overridevirtual 
Reads, parameterizes, and populates the distance field based on the supplied stream.
This function assumes that the file begins with ASCII data, and that the binary data has been written in bit formulation and compressed using Zlib. The function will reinitialize all data members based on the data in the file, using preset values for max_distance_ and propagate_negative_distances_. All occupied cells will be added to the distance field.
[in]  stream  The stream from which to read 
Implements distance_field::DistanceField.
Definition at line 679 of file propagation_distance_field.cpp.

private 
Removes a valid set of integer points from the voxel grid.
voxel_points  Valid set of voxel points for removal 
Definition at line 303 of file propagation_distance_field.cpp.

overridevirtual 
Remove a set of obstacle points from the distance field, updating distance values accordingly.
This function is relatively less efficient than adding points to the field in terms of positive distances  adding a given number of points will be less comptationally expensive than removing the same number of points. This is due to the nature of the propagation algorithm  when removing sets of cells, we must search outward from the freed cells and then propagate inward. Negative distances can be propagated more efficiently, as propagation can occur outward from newly freed cells without requiring a search step. If the set of occupied points that remain after removal is small it may be more efficient to call reset and then to add the remaining points rather than removing a set of points.
[in]  points  The set of obstacle points that will be set as free 
Implements distance_field::DistanceField.
Definition at line 198 of file propagation_distance_field.cpp.

overridevirtual 
Resets the entire distance field to max_distance for positive values and zero for negative values.
Implements distance_field::DistanceField.
Definition at line 510 of file propagation_distance_field.cpp.

overridevirtual 
This function will remove any obstacle points that are in the old point set but not the new point set, and add any obstacle points that are in the new block set but not the old block set. Any points that are in both sets are left unchanged. For more information see DistanceField::updatePointsInField.
The implementation of this function finds the set of points that are in the old_points and not the new_points, and the in the new_points and not the old_points using std::set_difference. It then calls a removal function on the former set, and an addition function on the latter set.
If there is no overlap between the old_points and the new_points it is more efficient to first call removePointsFromField on the old_points and then addPointsToField on the new points  this does not require computing set differences.
[in]  old_points  The set of points that all should be obstacle cells in the distance field 
[in]  new_points  The set of points, all of which are intended to be obstacle points in the distance field 
Implements distance_field::DistanceField.
Definition at line 119 of file propagation_distance_field.cpp.

overridevirtual 
Converts from a world location to a set of integer indices. Should return false if the world location is not valid in the distance field, and should populate the index values in either case.
[in]  world_x  The world X location 
[in]  world_y  The world Y location 
[in]  world_z  The world Z location 
[out]  x  The computed integer X location 
[out]  y  The computed integer X location 
[out]  z  The computed integer X location 
Implements distance_field::DistanceField.
Definition at line 634 of file propagation_distance_field.cpp.

overridevirtual 
Writes the contents of the distance field to the supplied stream.
This function writes the resolution, size, and origin parameters to the file in ASCII. It then writes the occupancy data only in bit form (with values or 1 representing occupancy, and 0 representing empty space). It further runs Zlib compression on the binary data before actually writing to disk. The max_distance and propagate_negative_distances values are not written to file, and the distances themselves will need to be recreated on load.
[out]  stream  The stream to which to write the distance field contents. 
Implements distance_field::DistanceField.
Definition at line 639 of file propagation_distance_field.cpp.

private 
Structure used to hold propagation frontier.
Data member that holds points from which to propagate, where each vector holds points that are a particular integer distance from the closest obstacle points
Definition at line 547 of file propagation_distance_field.h.

private 
Holds conversion from direction number to integer changes.
Definition at line 577 of file propagation_distance_field.h.

private 
Holds maximum distance.
Definition at line 558 of file propagation_distance_field.h.

private 
Holds maximum distance squared in cells.
Definition at line 559 of file propagation_distance_field.h.

private 
Data member that holds points from which to propagate in the negative, where each vector holds points that are a particular integer distance from the closest unoccupied points.
Definition at line 552 of file propagation_distance_field.h.

private 
Holds information on neighbor direction, with 27 different directions. Shows where to propagate given an integer distance and an update direction.
[0]  for expansion of d=0 [1]  for expansion of d>=1 Under this, we have the 27 directions Then, a list of neighborhoods for each direction
Definition at line 575 of file propagation_distance_field.h.

private 
Whether or not to propagate negative distances.
Definition at line 542 of file propagation_distance_field.h.

private 
Precomputed square root table for faster distance lookups.
Definition at line 561 of file propagation_distance_field.h.

private 
Actual container for distance data.
Definition at line 544 of file propagation_distance_field.h.