Hi Alex,

Thanks for the quick reply! In our 16 ms timed function call, we do have a RequestUpdateAll(). But removing it results in no rendering or update of the graphics objects. As part of the requirements we need to update the renderers at 16ms. However this is impossible to achieve with the current implementation. When we use ForceImmediateUpdateAll(), it causes a crash. This probably because another process is also updating a renderer at the same time.

Is there an alternative method of updating the renderers at a 60 hz frequency?

Best,

Keshav

On 5/26/2011 3:32 PM, Seitel, Alexander wrote:

Hi Keshav,

your IGT-pipeline initialization looks fine. Perhaps you should try to call Update() only once on the TrackingDeviceSource associated to the NDI Polaris instead of calling it for every filter. Do you also repeatedly update the rendering process with e.g. RequestUpdateAll()? Try to minimize those update calls as they will result in triggering the whole IGT-Pipeline / Rendering mechanism.

Please let us know if you have any success with this.

Best regards,

Alex

*Von:*Keshav Chintamani [mailto:[email protected]]
*Gesendet:* Donnerstag, 26. Mai 2011 14:16
*An:* [email protected]
*Cc:* Wegner, Ingmar; Neuhaus, Jochen; Nolden, Marco
*Betreff:* [mitk-users] Very low frame rates observed

Hello MITK users,

We are using the filters in the mitkIGT module for an head mounted display based augmented reality application and have some concerns regarding the filter pipelines. In particular, the frame rates obtained during rendering is very low.

We use a NDI Polaris spectra with 5 rigid bodies.

Essentially, there are three filter objects:

mitk::NavigationDataObjectVisualizationFilter::Pointer m_Visualizer


mitk::CameraVisualization::Pointer  m_LeftEye


mitk::CameraVisualization::Pointer  m_RightEye


which are initialized once and passed the required parameters:
-----------------------------------------------------------------------------
//Create instances of camera visualizers for left and right HMDs
m_TrackingManager->m_CameraVisualizerLeftHMD = mitk::CameraVisualization::New(); m_TrackingManager->m_CameraVisualizerRightHMD =mitk::CameraVisualization::New();

    //set Renderer
m_TrackingManager->m_CameraVisualizerLeftHMD->SetRenderer(mitk::BaseRenderer::GetInstance(leftWin->GetRenderWindow()->GetRenderWindow())); m_TrackingManager->m_CameraVisualizerRightHMD->SetRenderer(mitk::BaseRenderer::GetInstance(rightWin->GetRenderWindow()->GetRenderWindow()));

    //set viewing direction
    mitk::Vector3D viewVector;
    mitk::FillVector3D( viewVector, 0.0, 0.0, -1.0 );
m_TrackingManager->m_CameraVisualizerLeftHMD->SetDirectionOfProjectionInToolCoordinates(viewVector); m_TrackingManager->m_CameraVisualizerRightHMD->SetDirectionOfProjectionInToolCoordinates(viewVector);

    //set view up vector
    mitk::Vector3D upVector;
    //mitk::FillVector3D( upVector, -1.0, 0.0, 0.0 );
    mitk::FillVector3D( upVector, 0.0, 1.0, 0.0 );

m_TrackingManager->m_CameraVisualizerLeftHMD->SetViewUpInToolCoordinates(upVector);
    m_TrackingManager->m_CameraVisualizerLeftHMD->SetViewAngle(50);
    m_TrackingManager->m_CameraVisualizerLeftHMD->SetFocalLength(500);

m_TrackingManager->m_CameraVisualizerRightHMD->SetViewUpInToolCoordinates(upVector);
    m_TrackingManager->m_CameraVisualizerRightHMD->SetViewAngle(50);
    m_TrackingManager->m_CameraVisualizerRightHMD->SetFocalLength(500);

m_TrackingManager->m_Visualizer->SetInput(i, m_TrackingManager->GetNavDataFromIndex(i)); // set input for visualization filter

     m_TrackingManager->GetToolNameFromIndex(i);
mitk::DataNode::Pointer toolrepresentationNode = m_TrackingManager->CreateGizmoRGBNode(toolName.c_str());
     pDataStorage->Add(toolrepresentationNode);
m_TrackingManager->m_Visualizer->SetRepresentationObject(i, toolrepresentationNode->GetData()); // set instrument nodes as baseData for visualisation filter
*
*-----------------------------------------------------------------------------
*


m_Visualizer*updates the 6 polydata corresponding to each tool in the multi-widget 3D renderwindow

*m_LeftEye* updates the HMD left eye viewpoint in a QMITKRenderWindow

*m_RightEye* updates the HMD right eye viewpoint in a different QMITKRenderWindow.



A figure describing our filter update and a code snippet is attached.

//NavigationDataFiltersUpdate() is called by a Qt signal-slot on a timer update every 50 ms
void CamdassTrackingManager::NavigationDataFiltersUpdate()
{

   if(m_NDITrackingDevice.IsNull())
   {
      return;
   }
    if (m_Visualizer.IsNull())
         return;

    m_Visualizer->Update();

if(m_CameraVisualizerLeftHMD.IsNotNull() && m_CameraVisualizerRightHMD.IsNotNull())
    {
         m_CameraVisualizerLeftHMD->Update();
         m_CameraVisualizerRightHMD->Update();

     }
}

Every 50ms, these filters are updated using the *->Update()* call.

   1. When the tracking is initialized, using FRAPS we see a very low
      frame rate of 3 to 20 fps on the renderwindows
   2. When the tracking is initialized, using the mouse interactor
      (rotating the view) on the renderwindow raises the frame rate
      slightly
   3. However when the tracking pipeline is not initialized, and we
      use the mouse to rotate the 3D renderwindow, we get a frame rate
      of 56-60 hz


Is there a reason for the rendering rate to drop so low in the QmitkRenderWindows with the tracking running? And is calling Update() on the filters the correct way to push/pull data from the NDI device?

Any help to rectify this issue is welcome!

Regards,

Keshav




--
Keshav Chintamani,
Systems Engineer
Space Applications Services NV
Leuvensesteenweg 325
1932 Zaventem
Belgium
Tel: +32 2 721 54 84 Fax: +32 2 721 54 44
URL:http://www.spaceapplications.com


--
Keshav Chintamani,
Systems Engineer
Space Applications Services NV
Leuvensesteenweg 325
1932 Zaventem
Belgium
Tel: +32 2 721 54 84 Fax: +32 2 721 54 44
URL: http://www.spaceapplications.com


<<attachment: keshav_chintamani.vcf>>

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