diff --git a/src/src/Rendering/Core/DraggableActor.cpp b/src/src/Rendering/Core/DraggableActor.cpp
index b17769a..6a76ea8 100644
--- a/src/src/Rendering/Core/DraggableActor.cpp
+++ b/src/src/Rendering/Core/DraggableActor.cpp
@@ -142,7 +142,14 @@ void DraggableActor::ReleaseGraphicsResources(vtkWindow *window) {
 }
 
 int DraggableActor::RenderOverlay(vtkViewport *viewport) {
-    BuildShape();
+    if (BaseDataPoints->GetNumberOfPoints()<=0) return vtkProp::RenderOverlay(viewport);
+    QString newRenderTime = QString("%1-%2-%3").arg(BaseDataPoints->GetMTime())
+        .arg(Renderer->GetMTime()).arg(Renderer->GetActiveCamera()->GetMTime());
+    if (mRenderTime != newRenderTime) 
+    {
+        BuildShape();
+        mRenderTime=newRenderTime;
+    }
     if (senseArea->GetVisibility())senseArea->RenderOverlay(viewport);
     if (shadow2D->GetVisibility())shadow2D->RenderOverlay(viewport);
     if (actor2D->GetVisibility())actor2D->RenderOverlay(viewport);
diff --git a/src/src/Rendering/Core/DraggableActor.h b/src/src/Rendering/Core/DraggableActor.h
index 1338830..82eabba 100644
--- a/src/src/Rendering/Core/DraggableActor.h
+++ b/src/src/Rendering/Core/DraggableActor.h
@@ -159,6 +159,7 @@ protected:
 
     PointMapMode MapMode = MapToSlice;
     void RebuildRenderPoint();
+    QString mRenderTime;
 private:
     DraggableActor(const DraggableActor &) = delete;
 
diff --git a/src/src/Rendering/Measure/EllipseAnnotationActor.cpp b/src/src/Rendering/Measure/EllipseAnnotationActor.cpp
index d7144d7..9741e19 100644
--- a/src/src/Rendering/Measure/EllipseAnnotationActor.cpp
+++ b/src/src/Rendering/Measure/EllipseAnnotationActor.cpp
@@ -39,16 +39,11 @@ namespace {
 }
 
 void EllipseAnnotationActor::BuildShape() {
-    if (!BaseDataPoints->GetNumberOfPoints()) return;
-    QString stamp = QString("%1-%2").arg(BaseDataPoints->GetMTime())
-            .arg(Renderer->GetActiveCamera()->GetMTime());
-    if (mRenderTime == stamp) return;
-    QStringList stamps = stamp.split("-");
-    QStringList renderTimes = mRenderTime.split("-");
-    mRenderTime = stamp;
+    QString stamp = QString("%1").arg(BaseDataPoints->GetMTime());
+    QStringList renderTimes = mRenderTime.split('-');
     RebuildRenderPoint();
     //base data change change message
-    if (stamps[0] != renderTimes[0])
+    if (stamp != renderTimes[0])
     {   double p_lt[3] = {0, 0, 0};
         double* disp_lt = controlP_lt->GetRenderPosition();
         MapScreenPointToWorld(disp_lt[0], disp_lt[1], this->Renderer, p_lt);
diff --git a/src/src/Rendering/Measure/OpenPolyAnnotationActor.cpp b/src/src/Rendering/Measure/OpenPolyAnnotationActor.cpp
index e5ee471..65ef248 100644
--- a/src/src/Rendering/Measure/OpenPolyAnnotationActor.cpp
+++ b/src/src/Rendering/Measure/OpenPolyAnnotationActor.cpp
@@ -30,11 +30,6 @@ void OpenPolyAnnotationActor::SetRenderer(vtkRenderer *ren) {
 }
 
 void OpenPolyAnnotationActor::BuildShape() {
-    if (!BaseDataPoints->GetNumberOfPoints()) return;
-    QString stamp = QString("%1-%2").arg(BaseDataPoints->GetMTime())
-            .arg(Renderer->GetActiveCamera()->GetMTime());
-    if (mRenderTime == stamp) return;
-    mRenderTime = stamp;
     RebuildRenderPoint();
     vtkNew<vtkPolyLineSource> source;
     source->SetClosed(this->Closed);
diff --git a/src/src/Rendering/Measure/RoundAnnotationActor.cpp b/src/src/Rendering/Measure/RoundAnnotationActor.cpp
index fbfb622..b5823dd 100644
--- a/src/src/Rendering/Measure/RoundAnnotationActor.cpp
+++ b/src/src/Rendering/Measure/RoundAnnotationActor.cpp
@@ -39,16 +39,11 @@ namespace {
 }
 
 void RoundAnnotationActor::BuildShape() {
-    if (!BaseDataPoints->GetNumberOfPoints()) return;
-    QString stamp = QString("%1-%2").arg(BaseDataPoints->GetMTime())
-            .arg(Renderer->GetActiveCamera()->GetMTime());
-    if (mRenderTime == stamp) return;
-    QStringList stamps = stamp.split("-");
-    QStringList renderTimes = mRenderTime.split("-");
-    mRenderTime = stamp;
+    QString stamp = QString("%1").arg(BaseDataPoints->GetMTime());
+    QStringList renderTimes = mRenderTime.split('-');
     RebuildRenderPoint();
     //base data change change message
-    if (stamps[0] != renderTimes[0])
+    if (stamp != renderTimes[0])
     {   double p_lt[3] = {0, 0, 0};
         double* disp_lt = controlP_lt->GetRenderPosition();
         MapScreenPointToWorld(disp_lt[0], disp_lt[1], this->Renderer, p_lt);