diff --git a/examples/16_network/pet_segmentation_anim.py b/examples/16_network/pet_segmentation_anim.py
index cc0dc23c..1cb84452 100644
--- a/examples/16_network/pet_segmentation_anim.py
+++ b/examples/16_network/pet_segmentation_anim.py
@@ -37,12 +37,14 @@ def save(self, *args, **kwargs):
 # %%
 # Overlaod of class to pick up
 TRACKS = list()
+INDICES = list()
 
 
 class MyTrack(TrackEddiesObservations):
     @staticmethod
     def get_next_obs(i_current, ids, x, y, time_s, time_e, time_ref, window, **kwargs):
         TRACKS.append(ids["track"].copy())
+        INDICES.append(i_current)
         return TrackEddiesObservations.get_next_obs(
             i_current, ids, x, y, time_s, time_e, time_ref, window, **kwargs
         )
@@ -70,9 +72,13 @@ def get_next_obs(i_current, ids, x, y, time_s, time_e, time_ref, window, **kwarg
 def update(i_frame):
     tr = TRACKS[i_frame]
     mappable_tracks.set_array(tr)
-    s = 80 * ones(tr.shape)
+    s = 40 * ones(tr.shape)
     s[tr == 0] = 4
     mappable_tracks.set_sizes(s)
+
+    indices_frames = INDICES[i_frame]
+    mappable_CONTOUR.set_data(e.contour_lon_e[indices_frames], e.contour_lat_e[indices_frames],)
+    mappable_CONTOUR.set_color(cmap.colors[tr[indices_frames] % len(cmap.colors)])
     return (mappable_tracks,)
 
 
@@ -85,6 +91,9 @@ def update(i_frame):
 mappable_tracks = ax.scatter(
     e.lon, e.lat, c=TRACKS[0], cmap=cmap, vmin=0, vmax=vmax, s=20
 )
+mappable_CONTOUR = ax.plot(
+    e.contour_lon_e[INDICES[0]], e.contour_lat_e[INDICES[0]], color=cmap.colors[0]
+)[0]
 ani = VideoAnimation(
     fig, update, frames=range(1, len(TRACKS), 4), interval=125, blit=True
-)
+)
\ No newline at end of file
diff --git a/src/py_eddy_tracker/generic.py b/src/py_eddy_tracker/generic.py
index d6915088..1c066b0a 100644
--- a/src/py_eddy_tracker/generic.py
+++ b/src/py_eddy_tracker/generic.py
@@ -70,6 +70,8 @@ def build_index(groups):
     :param array groups: array which contain group to be separated
     :return: (first_index of each group, last_index of each group, value to shift group)
     :rtype: (array, array, int)
+
+    [0,0,1,1,1, 2] -> ([0, 2, 5], [2, 5, 6], 0)
     """
     i0, i1 = groups.min(), groups.max()
     amplitude = i1 - i0 + 1
@@ -191,59 +193,7 @@ def interp2d_geo(x_g, y_g, z_g, m_g, x, y, nearest=False):
     :return: z interpolated
     :rtype: array
     """
-    if nearest:
-        return interp2d_nearest(x_g, y_g, z_g, x, y)
-    else:
-        return interp2d_bilinear(x_g, y_g, z_g, m_g, x, y)
-
-
-@njit(cache=True, fastmath=True)
-def interp2d_nearest(x_g, y_g, z_g, x, y):
-    """
-    Nearest interpolation with wrapping if circular
-
-    :param array x_g: coordinates of grid
-    :param array y_g: coordinates of grid
-    :param array z_g: Grid value
-    :param array x: coordinate where interpolate z
-    :param array y: coordinate where interpolate z
-    :return: z interpolated
-    :rtype: array
-    """
-    x_ref = x_g[0]
-    y_ref = y_g[0]
-    x_step = x_g[1] - x_ref
-    y_step = y_g[1] - y_ref
-    nb_x = x_g.shape[0]
-    nb_y = y_g.shape[0]
-    is_circular = abs(x_g[-1] % 360 - (x_g[0] - x_step) % 360) < 1e-5
-    z = empty(x.shape, dtype=z_g.dtype)
-    for i in prange(x.size):
-        i0 = int(round((x[i] - x_ref) / x_step))
-        j0 = int(round((y[i] - y_ref) / y_step))
-        if is_circular:
-            i0 %= nb_x
-        if i0 >= nb_x or i0 < 0 or j0 < 0 or j0 >= nb_y:
-            z[i] = nan
-            continue
-        z[i] = z_g[i0, j0]
-    return z
-
-
-@njit(cache=True, fastmath=True)
-def interp2d_bilinear(x_g, y_g, z_g, m_g, x, y):
-    """
-    Bilinear interpolation with wrapping if circular
-
-    :param array x_g: coordinates of grid
-    :param array y_g: coordinates of grid
-    :param array z_g: Grid value
-    :param array m_g: Boolean grid, True if value is masked
-    :param array x: coordinate where interpolate z
-    :param array y: coordinate where interpolate z
-    :return: z interpolated
-    :rtype: array
-    """
+    # TODO : Maybe test if we are out of bounds
     x_ref = x_g[0]
     y_ref = y_g[0]
     x_step = x_g[1] - x_ref
@@ -251,46 +201,46 @@ def interp2d_bilinear(x_g, y_g, z_g, m_g, x, y):
     nb_x = x_g.shape[0]
     nb_y = y_g.shape[0]
     is_circular = abs(x_g[-1] % 360 - (x_g[0] - x_step) % 360) < 1e-5
-    # Indices which should be never exist
-    i0_old, j0_old, masked = -100000000, -10000000, False
     z = empty(x.shape, dtype=z_g.dtype)
     for i in prange(x.size):
         x_ = (x[i] - x_ref) / x_step
         y_ = (y[i] - y_ref) / y_step
         i0 = int(floor(x_))
+        i1 = i0 + 1
+        xd = x_ - i0
         j0 = int(floor(y_))
-        # corner are the same need only a new xd and yd
-        if i0 != i0_old or j0 != j0_old:
-            i1 = i0 + 1
-            j1 = j0 + 1
-            if is_circular:
-                i0 %= nb_x
-                i1 %= nb_x
+        j1 = j0 + 1
+        if is_circular:
+            i0 %= nb_x
+            i1 %= nb_x
+        else:
             if i1 >= nb_x or i0 < 0 or j0 < 0 or j1 >= nb_y:
-                masked = True
-            else:
-                masked = False
-            if not masked:
-                if m_g[i0, j0] or m_g[i0, j1] or m_g[i1, j0] or m_g[i1, j1]:
-                    masked = True
-                else:
-                    z00, z01, z10, z11 = (
-                        z_g[i0, j0],
-                        z_g[i0, j1],
-                        z_g[i1, j0],
-                        z_g[i1, j1],
-                    )
-                    masked = False
-            # Need to be store only on change
-            i0_old, j0_old = i0, j0
-        if masked:
+                z[i] = nan
+                continue
+
+        yd = y_ - j0
+        z00 = z_g[i0, j0]
+        z01 = z_g[i0, j1]
+        z10 = z_g[i1, j0]
+        z11 = z_g[i1, j1]
+        if m_g[i0, j0] or m_g[i0, j1] or m_g[i1, j0] or m_g[i1, j1]:
             z[i] = nan
         else:
-            xd = x_ - i0
-            yd = y_ - j0
-            z[i] = (z00 * (1 - xd) + (z10 * xd)) * (1 - yd) + (
-                z01 * (1 - xd) + z11 * xd
-            ) * yd
+            if nearest:
+                if xd <= 0.5:
+                    if yd <= 0.5:
+                        z[i] = z00
+                    else:
+                        z[i] = z01
+                else:
+                    if yd <= 0.5:
+                        z[i] = z10
+                    else:
+                        z[i] = z11
+            else:
+                z[i] = (z00 * (1 - xd) + (z10 * xd)) * (1 - yd) + (
+                    z01 * (1 - xd) + z11 * xd
+                ) * yd
     return z
 
 
diff --git a/src/py_eddy_tracker/observations/network.py b/src/py_eddy_tracker/observations/network.py
index d8c339cf..f2f30ade 100644
--- a/src/py_eddy_tracker/observations/network.py
+++ b/src/py_eddy_tracker/observations/network.py
@@ -164,6 +164,9 @@ def obs_relative_order(self, i_obs):
         return self.segment_relative_order(self.segment[i_obs])
 
     def connexions(self, multi_network=False):
+        """
+        create dictionnary for each segments, gives the segments which interact with
+        """
         if multi_network:
             segment = self.segment_track_array
         else:
@@ -648,10 +651,12 @@ def dissociate_network(self):
         """
         Dissociate network with no known interaction (spliting/merging)
         """
-        self.only_one_network()
-        tags = self.tag_segment()
-        # FIXME : Ok if only one network
-        self.track[:] = tags[self.segment - 1]
+
+        tags = self.tag_segment(multi_network=True)
+        if self.track[0] == 0:
+            tags -= 1
+
+        self.track[:] = tags[self.segment_track_array]
 
         i_sort = self.obs.argsort(order=("track", "segment", "time"), kind="mergesort")
         # Sort directly obs, with hope to save memory
@@ -672,23 +677,42 @@ def network(self, id_network):
 
     @classmethod
     def __tag_segment(cls, seg, tag, groups, connexions):
+        """
+        Will set same temporary ID for each connected segment.
+
+        :param int seg: current ID of seg
+        :param ing tag: temporary ID to set for seg and its connexion
+        :param array[int] groups: array where tag will be stored
+        :param dict connexions: gives for one ID of seg all seg connected
+        """
+        # If seg are already used we stop recursivity
+        seg_corrected = seg - 1
         if groups[seg] != 0:
             return
+        # We set tag for this seg
         groups[seg] = tag
-        segs = connexions.get(seg + 1, None)
+        # Get all connexions of this seg
+        segs = connexions.get(seg, None)
         if segs is not None:
             for seg in segs:
-                cls.__tag_segment(seg - 1, tag, groups, connexions)
+                # For each connexion we apply same function
+                cls.__tag_segment(seg, tag, groups, connexions)
 
-    def tag_segment(self):
-        self.only_one_network()
-        nb = self.segment.max()
+
+    def tag_segment(self, multi_network=False):
+        if multi_network:
+            nb = self.segment_track_array[-1]+1
+        else:
+            nb = self.segment.max()+1
         sub_group = zeros(nb, dtype="u4")
-        c = self.connexions()
+        c = self.connexions(multi_network=multi_network)
         j = 1
+        # for each available id
         for i in range(nb):
+            # Skip if already set
             if sub_group[i] != 0:
                 continue
+            # we tag an unset segments and explore all connexions
             self.__tag_segment(i, j, sub_group, c)
             j += 1
         return sub_group