diff --git a/Applications/VpView/vpVidtkTrackIO.cxx b/Applications/VpView/vpVidtkTrackIO.cxx
index 5ddf62df..76c584f9 100644
--- a/Applications/VpView/vpVidtkTrackIO.cxx
+++ b/Applications/VpView/vpVidtkTrackIO.cxx
@@ -632,13 +632,14 @@ bool vpVidtkTrackIO::WriteTracks(
 
       double lat = 444.0;
       double lon = 444.0;
-      vidtk::image_object_sptr obj;
+      vidtk::image_object* obj= nullptr;
       vgl_box_2d<unsigned int> imageBox;
       bool validObject = false;
 
       if (orig_state && !orig_state->latitude_longitude(lat, lon))
         {
-        if (orig_state->image_object(obj))
+        obj = orig_state->get_image_object();
+        if (obj != nullptr)
           {
           validObject = true;
           imageBox = obj->get_bbox();
@@ -746,8 +747,7 @@ bool vpVidtkTrackIO::WriteTracks(
         new_obj->set_bbox(newBox);
         }
 
-      new_objs[0] = new_obj;
-      new_state->data_.set(vidtk::tracking_keys::img_objs, new_objs);
+      new_state->set_image_object(new_obj);
 
       track->add_state(new_state);
       }
@@ -936,7 +936,7 @@ void vpVidtkTrackIO::ReadTrack(
   points.reserve(12);
 
   bool skippedInterpolationPointSinceLastInsert = false;
-  std::vector<vidtk::image_object_sptr> objs;
+  vidtk::image_object_sptr obj;
   for (const auto& trackState : trackHistory)
     {
     const auto frameNumber = trackState->time_.frame_number();
@@ -973,12 +973,13 @@ void vpVidtkTrackIO::ReadTrack(
       timeStamp.SetTime(trackState->time_.time());
       }
 
-    if (trackState->data_.get(vidtk::tracking_keys::img_objs, objs))
+    obj = trackState->get_image_object();
+    if (obj != nullptr)
       {
       double lat, lon;
       if (!trackState->latitude_longitude(lat, lon))
         {
-        const auto& world_loc = objs[0]->get_world_loc();
+        const auto& world_loc = obj->get_world_loc();
         lon = world_loc[0];
         lat = world_loc[1];
         }
@@ -987,7 +988,7 @@ void vpVidtkTrackIO::ReadTrack(
       bool trackPointAvailable = true;
       double minY;
       double maxY;
-      const auto& vglBBox = objs[0]->get_bbox();
+      const auto& vglBBox = obj->get_bbox();
       double pt[4] = {0.0, 0.0, 0.0, 1.0};
       vpFrame frameMetaData;
       if (this->StorageMode == TSM_TransformedGeoCoords)
@@ -1005,7 +1006,7 @@ void vpVidtkTrackIO::ReadTrack(
         }
       else
         {
-        const auto& image_loc = objs[0]->get_image_loc();
+        const auto& image_loc = obj->get_image_loc();
         pt[0] = image_loc[0];
         unsigned int imageMaxY = this->Reader.GetImageHeight() - 1;
         if (this->StorageMode == TSM_InvertedImageCoords)
diff --git a/Libraries/VtkVgCore/vtkVgTrack.cxx b/Libraries/VtkVgCore/vtkVgTrack.cxx
index 334f1efb..ffd1b5b2 100644
--- a/Libraries/VtkVgCore/vtkVgTrack.cxx
+++ b/Libraries/VtkVgCore/vtkVgTrack.cxx
@@ -397,6 +397,8 @@ void vtkVgTrack::InsertNextPoint(const vtkVgTimeStamp& timeStamp,
                                  vtkPoints* fromShellPoints,
                                  vtkIdType fromShellPtsStart)
 {
+  vtkDebugMacro("insert next point: " << timeStamp);
+
   if (!this->Points)
     {
     vtkErrorMacro("Must set Points before inserting track points!");
@@ -709,6 +711,7 @@ void vtkVgTrack::SetPoint(const vtkVgTimeStamp& timeStamp,
                           vtkPoints* fromShellPts,
                           vtkIdType fromShellPtsStart)
 {
+  vtkDebugMacro("set point: " << timeStamp);
   // if not closed and after the last point, just use InsertNextPoint()
   if (!this->EndFrame.IsValid() &&
       (this->Internal->PointIdMap.size() == 0 ||
diff --git a/Libraries/VvVidtk/vvAdaptVidtk.cxx b/Libraries/VvVidtk/vvAdaptVidtk.cxx
index 185e85de..50c88d7c 100644
--- a/Libraries/VvVidtk/vvAdaptVidtk.cxx
+++ b/Libraries/VvVidtk/vvAdaptVidtk.cxx
@@ -18,12 +18,11 @@
 QList<vvTrackState> vvAdapt(const vidtk::track_state& vs)
 {
   QList<vvTrackState> stateList;
-  std::vector<vidtk::image_object_sptr> objs;
-  if (vs.data_.get(vidtk::tracking_keys::img_objs, objs))
+  vidtk::image_object* obj_sptr = vs.get_image_object();
+  if (obj_sptr != nullptr)
     {
-    for (size_t i = 0; i < objs.size(); ++i)
       {
-      const vidtk::image_object& obj = *objs[i];
+      const vidtk::image_object& obj = *obj_sptr;
 
       vvTrackState state;
 
@@ -38,8 +37,8 @@ QList<vvTrackState> vvAdapt(const vidtk::track_state& vs)
         }
 
       // Set image point and box
-      const auto& img_loc = objs[i]->get_image_loc();
-      const auto& bbox = objs[i]->get_bbox();
+      const auto& img_loc = obj_sptr->get_image_loc();
+      const auto& bbox = obj_sptr->get_bbox();
       state.ImagePoint.X = img_loc[0];
       state.ImagePoint.Y = img_loc[1];
       state.ImageBox.TopLeft.X = bbox.min_x();