if(usegpu && _vol->GetDataDimension() > 2){
_volumeMappergpu = vtkGPUVolumeRayCastMapper::New();
_volumeMappergpu->SetClippingPlanes( _volumePlanes );
if(usegpu && _vol->GetDataDimension() > 2){
_volumeMappergpu = vtkGPUVolumeRayCastMapper::New();
_volumeMappergpu->SetClippingPlanes( _volumePlanes );