How to Track the updated Octree in OctoMap

Octree disables the detection of changement as default, which is same with enableChangeDetection(false)
To track the update/change of Octree, enableChangeDetection(true) should be called once, after its construction.
Important After detection of change, it must be reset via resetChangeDetection()

Code Example

#include <octomap/OccupancyOcTreeBase.h>
#include <octomap/OcTree.h>
#include <octomap/octomap.h>
#include <octomap/math/Utils.h>

octomap::OcTree *m_octree;

m_octree = new octomap::OcTree(octomap_resolution);
m_octree->setProbHit(octomap_hit);
m_octree->setProbMiss(octomap_miss);

m_octree->enableChangeDetection(true); // important!!!
//m_octree->enableChangeDetection(false);


void track_changed_octree(octomap::OcTree *octree){
  octomap::KeyBoolMap::const_iterator it;
  for (it=octree->changedKeysBegin(); it!=octree->changedKeysEnd(); it++) {
    octomap::OcTreeNode* node = octree->search(it->first); // it->first is now key, since KeyBoolMap is structure.
    if (node){ // ----> has value
      if (octree->isNodeOccupied(node)){ 
        // occupied....
      }
      else{ 
        // free...
      }
    }
    else{ // does not have value, unknown -----> missing
      // missing...
    }
  }
  octree->resetChangeDetection(); //important!!!!
}