--- a/python/moving.py	Mon May 18 17:17:06 2015 +0200
+++ b/python/moving.py	Tue May 19 16:58:26 2015 +0200
@@ -1010,30 +1010,34 @@
             # positions
             positions = Trajectory()
             for t in newTimeInterval:
+                nTotal = 0.
                 p = Point(0.,0.)
-                n = 0.
-                if obj1.existsAtInstant(t):
-                    p += obj1.getPositionAtInstant(t)
-                    n += 1.
-                if obj2.existsAtInstant(t):
-                    p += obj2.getPositionAtInstant(t)
-                    n += 1.
-                assert n>0, 'there should be at least one point for each instant'
-                positions.addPosition(p.divide(n))
+                for obj in [obj1, obj2]:
+                    if obj.existsAtInstant(t):
+                        if obj.hasFeatures():
+                            n = len([f for f in obj.getFeatures() if f.existsAtInstant(t)])
+                        else:
+                            n = 1.
+                        p += obj.getPositionAtInstant(t).multiply(n)
+                        nTotal += n
+                assert nTotal>0, 'there should be at least one point for each instant'
+                positions.addPosition(p.divide(nTotal))
             # velocities: if any
             if hasattr(obj1, 'velocities') and hasattr(obj2, 'velocities'):
                 velocities = Trajectory()
                 for t in newTimeInterval:
+                    nTotal = 0.
                     p = Point(0.,0.)
-                    n = 0.
-                    if obj1.existsAtInstant(t):
-                        p += obj1.getVelocityAtInstant(t)
-                        n += 1.
-                    if obj2.existsAtInstant(t):
-                        p += obj2.getVelocityAtInstant(t)
-                        n += 1.
+                    for obj in [obj1, obj2]:
+                        if obj.existsAtInstant(t):
+                            if obj.hasFeatures():
+                                n = len([f for f in obj.getFeatures() if f.existsAtInstant(t)])
+                            else:
+                                n = 1.
+                            p += obj.getVelocityAtInstant(t).multiply(n)
+                            nTotal += n
                     assert n>0, 'there should be at least one point for each instant'
-                    velocities.addPosition(p.divide(n))
+                    velocities.addPosition(p.divide(nTotal))
             else:
                 velocities = None
             # TODO object envelop (polygon)
@@ -1041,7 +1045,10 @@
             if obj1.getUserType() != obj2.getUserType():
                 print('The two moving objects have different user types: obj1 {} obj2 {}'.format(userTypeNames[obj1.getUserType()], userTypeNames[obj2.getUserType()]))
 
-            return MovingObject(newNum, newTimeInterval, positions, velocities, userType = obj1.getUserType())
+            newObject = MovingObject(newNum, newTimeInterval, positions, velocities, userType = obj1.getUserType())
+            if obj1.hasFeatures() and obj2.hasFeatures():
+                newObject.features = obj1.getFeatures()+obj2.getFeatures()
+            return newObject
 
     def getObjectInTimeInterval(self, inter):
         '''Returns a new object extracted from self,