diff --git a/c_source/pruning/pruneVoids.cpp b/c_source/pruning/pruneVoids.cpp
index 3927608..534abc0 100644
--- a/c_source/pruning/pruneVoids.cpp
+++ b/c_source/pruning/pruneVoids.cpp
@@ -469,8 +469,10 @@ int main(int argc, char **argv) {
   interval = 1.*(clock4 - clock3)/CLOCKS_PER_SEC;
   printf(" Read voids (%.2f sec)...\n", interval);
 
-  // load voids *again* using Guilhem's code so we can get tree information
   clock3 = clock();
+// TODO - TEST NEW TREE BUILDING TECHNIQUE AND REMOVE THIS
+/*
+  // load voids *again* using Guilhem's code so we can get tree information
   printf(" Re-loading voids and building tree...\n");
   ZobovRep zobovCat;
   if (!loadZobov(args.voidDesc_arg, args.zone2Part_arg, args.void2Zone_arg, 
@@ -481,7 +483,65 @@ int main(int argc, char **argv) {
   VoidTree *tree;
   tree = new VoidTree(zobovCat);
   zobovCat.allZones.erase(zobovCat.allZones.begin(), zobovCat.allZones.end());
+*/
+
+  // if all of a void's zones also belong to another void,
+  // it is a child of that void
+  for (iVoid = 0; iVoid < numVoids; iVoid++) {
+    voidID = voids[iVoid].voidID;
+    int numMyZones = voids[iVoid].numZones;
+
+    for (int iCheck = 0; iCheck < numVoids; iCheck++) {
+      int numCheckZones = voids[iCheck].numZones;
+      if (numMyZones > numCheckZones) continue;
+      if (iVoid == iCheck) continue;
+
+      int checkID = voids[iCheck].voidID;
+
+      bool allZonesMatch = true;
+      for (iZ = 0; iZ < void2Zones[voidID].numZones; iZ++) {
+        int myZone = void2Zones[voidID].zoneIDs[iZ];
+     
+        bool foundMatch = false;
+        for (int jZ = 0; jZ < void2Zones[checkID].numZones; jZ++) {
+          int checkZone = void2Zones[checkID].zoneIDs[jZ];
+          foundMatch = myZone == checkZone;
+        }
+
+        if (not foundMatch) {
+          allZonesMatch = false;
+          break;
+        }
+      }
  
+      if (allZonesMatch) {
+        voids[iVoid].parentID = checkID;
+        voids[iCheck].numChildren++;
+      }
+    }
+
+  } // end building tree
+
+  // compute level in tree
+  for (iVoid = 0; iVoid < numVoids; iVoid++) {
+    int level = 0;
+    int parentID = voids[iVoid].parentID;
+    while (parentID != -1) {
+      level++;
+
+      // find the index of the parent
+      for (i = 0; i < numVoids; i++) {
+        if (voids[i].voidID == parentID) {
+          parentID = voids[i].voidID;
+          break;
+        }
+      }
+    }
+    voids[iVoid].level = level;
+  }
+
+// TODO - TEST NEW TREE BUILDING TECHNIQUE AND REMOVE THIS
+/* 
   // copy tree information to our own data structures
   for (iVoid = 0; iVoid < numVoids; iVoid++) {
     voidID = voids[iVoid].voidID;
@@ -497,9 +557,11 @@ int main(int argc, char **argv) {
     }
     voids[iVoid].level = level;
   }
+*/
+
   clock4 = clock();
   interval = 1.*(clock4 - clock3)/CLOCKS_PER_SEC;
-  printf(" Re-read voids (%.2f sec)...\n", interval);
+  printf(" Building void tree (%.2f sec)...\n", interval);
 
   printf(" Computing void properties...\n");
 
@@ -513,9 +575,6 @@ int main(int argc, char **argv) {
   // main processing of each void
   for (iVoid = 0; iVoid < numVoids; iVoid++) {
     voidID = voids[iVoid].voidID;
-    //printf("  Working on void %d (of %d) %d %d %f\n",iVoid+1, numVoids, voidID, 
-    //                                       voids[iVoid].numPart, 
-    //                                       voids[iVoid].radius);
 
     voids[iVoid].center[0] = part[voids[iVoid].coreParticle].x;
     voids[iVoid].center[1] = part[voids[iVoid].coreParticle].y;
diff --git a/python_source/backend/classes.py b/python_source/backend/classes.py
index 1e7e9c6..169f28b 100644
--- a/python_source/backend/classes.py
+++ b/python_source/backend/classes.py
@@ -21,11 +21,12 @@
 
 import os
 from numpy import abs
-#import matplotlib as mpl
-#mpl.use('Agg')
 
 LIGHT_SPEED = 299792.458
 
+CENTRAL_VOID = 1
+EDGE_VOID = 2
+
 class Stack:
   zMin = 0.0
   zMax = 0.1