diff --git a/MarkupToModel/MarkupToModel.py b/MarkupToModel/MarkupToModel.py
index 74b8e61..1ed8150 100644
--- a/MarkupToModel/MarkupToModel.py
+++ b/MarkupToModel/MarkupToModel.py
@@ -135,6 +135,10 @@ def setup(self):
     self.ui.outputSelector.connect("currentNodeChanged(vtkMRMLNode*)", self.updateParameterNodeFromGUI)
     self.ui.opacitySlider.connect("valueChanged(double)", self.updateParameterNodeFromGUI)
 
+    self.observedMarkupNode = None
+    self.markupsObserverTag = None
+    self.ui.autoUpdateCheckBox.connect("toggled(bool)", self.onEnableAutoUpdate)
+
     # Buttons
     self.ui.applyButton.connect('clicked(bool)', self.onApplyButton)
 
@@ -236,10 +240,24 @@ def updateParameterNodeFromGUI(self, caller=None, event=None):
 
     self._parameterNode.SetNodeReferenceID("InputVolume", self.ui.inputSelector.currentNodeID)
     self._parameterNode.SetNodeReferenceID("OutputVolume", self.ui.outputSelector.currentNodeID)
-    self.ui.outputSelector.currentNode().GetDisplayNode().SetOpacity(self.ui.opacitySlider.value)  #TODO: bugged
+    self.ui.outputSelector.currentNode().GetDisplayNode().SetOpacity(self.ui.opacitySlider.value)
 
     self._parameterNode.EndModify(wasModified)
 
+  def onEnableAutoUpdate(self, autoUpdate):
+    if self.markupsObserverTag:
+      self.observedMarkupNode.RemoveObserver(self.markupsObserverTag)
+      self.observedMarkupNode = None
+      self.markupsObserverTag = None
+    if autoUpdate and self.ui.inputSelector.currentNode:
+      self.observedMarkupNode = self.ui.inputSelector.currentNode()
+      self.markupsObserverTag = self.observedMarkupNode.AddObserver(
+        slicer.vtkMRMLMarkupsNode.PointModifiedEvent, self.onMarkupsUpdated
+      )
+  
+  def onMarkupsUpdated(self, caller=None, event=None):
+    self.onApplyButton()
+
   def onApplyButton(self):
     """
     Run processing when user clicks "Apply" button.
diff --git a/MarkupToModel/Resources/UI/MarkupToModel.ui b/MarkupToModel/Resources/UI/MarkupToModel.ui
index 91a3c6b..6488039 100644
--- a/MarkupToModel/Resources/UI/MarkupToModel.ui
+++ b/MarkupToModel/Resources/UI/MarkupToModel.ui
@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>270</width>
-    <height>159</height>
+    <width>274</width>
+    <height>191</height>
    </rect>
   </property>
   <layout class="QVBoxLayout" name="verticalLayout">
@@ -67,14 +67,14 @@
         </property>
        </widget>
       </item>
-      <item row="2" column="0">
+      <item row="3" column="0">
        <widget class="QLabel" name="label_3">
         <property name="text">
          <string>Opacity:</string>
         </property>
        </widget>
       </item>
-      <item row="2" column="1">
+      <item row="3" column="1">
        <widget class="qMRMLSliderWidget" name="opacitySlider">
         <property name="singleStep">
          <double>0.010000000000000</double>
@@ -90,6 +90,20 @@
         </property>
        </widget>
       </item>
+      <item row="4" column="0">
+       <widget class="QLabel" name="label_4">
+        <property name="text">
+         <string>Enable auto-udpate</string>
+        </property>
+       </widget>
+      </item>
+      <item row="4" column="1">
+       <widget class="QCheckBox" name="autoUpdateCheckBox">
+        <property name="text">
+         <string/>
+        </property>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>
diff --git a/MarkupToModel/__pycache__/MarkupToModel.cpython-36.pyc b/MarkupToModel/__pycache__/MarkupToModel.cpython-36.pyc
index d740ba3..bda12e3 100644
Binary files a/MarkupToModel/__pycache__/MarkupToModel.cpython-36.pyc and b/MarkupToModel/__pycache__/MarkupToModel.cpython-36.pyc differ