diff --git a/src/src/Rendering/Measure/OpenPolyAnnotationActor.cpp b/src/src/Rendering/Measure/OpenPolyAnnotationActor.cpp
index 7533e35..0a19124 100644
--- a/src/src/Rendering/Measure/OpenPolyAnnotationActor.cpp
+++ b/src/src/Rendering/Measure/OpenPolyAnnotationActor.cpp
@@ -10,6 +10,7 @@
 #include <vtkTextProperty.h>
 #include <vtkPolygon.h>
 #include <vtkLine.h>
+#include <vtkCamera.h>
 
 #include <QFile>
 #include <QCoreApplication>
@@ -30,6 +31,9 @@ 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;
     RebuildRenderPoint();
     vtkNew<vtkPolyLineSource> source;
     source->SetClosed(this->Closed);
diff --git a/src/src/Rendering/Measure/OpenPolyAnnotationActor.h b/src/src/Rendering/Measure/OpenPolyAnnotationActor.h
index fdaa261..daaa0c3 100644
--- a/src/src/Rendering/Measure/OpenPolyAnnotationActor.h
+++ b/src/src/Rendering/Measure/OpenPolyAnnotationActor.h
@@ -83,6 +83,7 @@ protected:
 
     vtkTextProperty *textProperty;
     bool measured;
+    QString mRenderTime;
     QString mUnitmm ;
     QString mUnitcm ;
     QString mUnitmm2;