Explorer.h

#ifndef EXPLORER_H
#define EXPLORER_H

#include <vector>
#include <geometry_msgs/Pose.h>

#include "GridMap.h"
#include "tools/tools.h"

namespace ExplorerConstants
{
  static int8_t UNKNOWN;
  static const int8_t NOT_SEEN_YET = -1;
  static const double MAX_DISTANCE = DBL_MAX;
  static const double MAX_COST = DBL_MAX;
  static const int OBSTACLE = INT_MAX;
}

/**
 * @class  Explorer
 * @author Malte Knauf, Stephan Wirth, David Gossow (RX)
 * @brief  Path planning & exploration class
 *
 * Usage:
 *
 * - Call setOccupancyMap() to set the base map for path finding.
 * - Set a start point by calling setStart()
 *
 * - For path planning:
 *   +Choose a target by calling setTarget()
 *   +To correct a target to the nearest approachable position,
 *    call getNearestAccessibleTarget
 *   +Call getPathTransformPath()
 *
 *  -For exploration:
 *   +Call resetExploration()
 *   +Call getExplorationTransformPath()
 *   +The calculated target is the last element in the returned path
 *
 * - Call sampleWaypointsFromPath() to extract waypoints from a calculated path
 *
 * This class uses a couple of "maps" for computation and storing data:
 *
 * - m_OccupancyMap stores the occupancy probabilities in double values. A value of 100 means
 *       totally occupied, 0 totally free.
 * - m_ObstacleDistanceMap stores in each cell the distance (one unit = one cell) to the nearest obstacle.
 *       This map is computed by an eucledian distance transformation from m_OccupancyMap.
 * - m_FrontierMap is a bool map which has 1 in frontier cells and 0 in all others. A frontier
 *       is defined as a free cell that has one of its four direct neighbours in unknown space and is "safe" for
 *       the robot (m_ObstacleDistanceMap is used for that).
 * - m_DrivingDistanceMap is a double map that stores for each cell the distance to m_Start. It is computed
 *       by a flood-fill (seed-fill) algorithm. The values are therefor only an approximation and not exact.
 *       m_DrivingDistanceMap is used to search the nearest frontier when requesting an auto target.
 * - m_TargetMap is a double map that stores for each cell the distance to m_Target. It is computed
 *       like m_DrivingDistanceMap. This map is used as heuristic for the A*-Pathfinding algorithm.
 * - m_NavigationMap is used to mark the cells that are touched by the A*-Pathfinding algorithm.
 *
 *
 * The coordinate system and units that are used in this class are based on map cells.
 * @see GridMap
 *
 */
class Explorer
{

  public:

    /**
     * @brief Default constructor.
     * @param minAllowedObstacleDistance,maxAllowedObstacleDistance Range of allowed distances to next obstacle [Pixels]