diff --git a/Core/Code/Rendering/mitkMapper.cpp b/Core/Code/Rendering/mitkMapper.cpp
index 62b7085436..4fbdcf2df9 100644
--- a/Core/Code/Rendering/mitkMapper.cpp
+++ b/Core/Code/Rendering/mitkMapper.cpp
@@ -1,164 +1,165 @@
 /*===================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center,
 Division of Medical and Biological Informatics.
 All rights reserved.
 
 This software is distributed WITHOUT ANY WARRANTY; without
 even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.
 
 See LICENSE.txt or http://www.mitk.org for details.
 
 ===================================================================*/
 
 
 #include "mitkMapper.h"
 #include "mitkDataNode.h"
 #include "mitkBaseRenderer.h"
 #include "mitkProperties.h"
 
 
 mitk::Mapper::Mapper()
-  :m_TimeStep( 0 )
+  : m_DataNode(NULL)
+  , m_TimeStep( 0 )
 {
 }
 
 
 mitk::Mapper::~Mapper()
 {
 }
 
 
 mitk::BaseData* mitk::Mapper::GetData() const
 {
-return m_DataNode->GetData();
+  return m_DataNode == NULL ? NULL : m_DataNode->GetData();
 }
 
 
 mitk::DataNode* mitk::Mapper::GetDataNode() const
 {
   return this->m_DataNode;
 }
 
 
 bool mitk::Mapper::GetColor(float rgb[3], mitk::BaseRenderer* renderer, const char* name) const
 {
     const mitk::DataNode* node=GetDataNode();
     if(node==NULL)
         return false;
 
     return node->GetColor(rgb, renderer, name);
 }
 
 bool mitk::Mapper::GetVisibility(bool &visible, mitk::BaseRenderer* renderer, const char* name) const
 {
     const mitk::DataNode* node=GetDataNode();
     if(node==NULL)
         return false;
 
     return node->GetVisibility(visible, renderer, name);
 }
 
 bool mitk::Mapper::GetOpacity(float &opacity, mitk::BaseRenderer* renderer, const char* name) const
 {
     const mitk::DataNode* node=GetDataNode();
     if(node==NULL)
         return false;
 
     return node->GetOpacity(opacity, renderer, name);
 }
 
 bool mitk::Mapper::GetLevelWindow(mitk::LevelWindow& levelWindow, mitk::BaseRenderer* renderer, const char* name) const
 {
     const mitk::DataNode* node=GetDataNode();
     if(node==NULL)
         return false;
 
     return node->GetLevelWindow(levelWindow, renderer, name);
 }
 
 
 bool mitk::Mapper::IsVisible(mitk::BaseRenderer* renderer, const char* name) const
 {
     bool visible = true;
     GetDataNode()->GetVisibility(visible, renderer, name);
     return visible;
 }
 
 
 void mitk::Mapper::CalculateTimeStep( mitk::BaseRenderer *renderer )
 {
   if ( ( renderer != NULL ) && ( m_DataNode != NULL ) )
   {
     m_TimeStep = renderer->GetTimeStep(m_DataNode->GetData());
   }
   else
   {
     m_TimeStep = 0;
   }
 }
 
 void mitk::Mapper::Update(mitk::BaseRenderer *renderer)
 {
   const DataNode* node = GetDataNode();
 
   assert(node!=NULL);
 
   mitk::BaseData * data = static_cast<mitk::BaseData *>(node->GetData());
 
   if (!data)
     return;
 
   // Calculate time step of the input data for the specified renderer (integer value)
   this->CalculateTimeStep( renderer );
 
   // Check if time step is valid
   const TimeSlicedGeometry *dataTimeGeometry = data->GetTimeSlicedGeometry();
   if ( ( dataTimeGeometry == NULL )
     || ( dataTimeGeometry->GetTimeSteps() == 0 )
     || ( !dataTimeGeometry->IsValidTime( m_TimeStep ) ) )
   {
     // TimeSlicedGeometry or time step is not valid for this data:
     // reset mapper so that nothing is displayed
     this->ResetMapper( renderer );
     return;
   }
 
   this->GenerateDataForRenderer(renderer);
 }
 
 
 bool mitk::Mapper::BaseLocalStorage::IsGenerateDataRequired(
     mitk::BaseRenderer *renderer,
     mitk::Mapper *mapper,
     mitk::DataNode *dataNode) const
 {
   if( mapper && m_LastGenerateDataTime < mapper -> GetMTime () )
     return true;
 
   if( dataNode )
   {
     if( m_LastGenerateDataTime < dataNode -> GetDataReferenceChangedTime () )
       return true;
 
     mitk::BaseData * data = dataNode -> GetData ( ) ;
 
     if( data && m_LastGenerateDataTime < data -> GetMTime ( ) )
       return true;
   }
 
   if( renderer && m_LastGenerateDataTime < renderer -> GetTimeStepUpdateTime ( ) )
     return true;
 
   return false;
 }
 
 void mitk::Mapper::SetDefaultProperties(mitk::DataNode* node, mitk::BaseRenderer* renderer, bool overwrite)
 {
   node->AddProperty( "visible", mitk::BoolProperty::New(true), renderer, overwrite );
   node->AddProperty( "layer", mitk::IntProperty::New(0), renderer, overwrite);
   node->AddProperty( "name", mitk::StringProperty::New("No Name!"), renderer, overwrite );
 }