Integration Nexus Vicon into 3D Slicer through PlusServer

[AurelieSar]

Dear PlusToolkit team,

As you may already know, we are working on the integration of Nexus Vicon into 3D Slicer through PlusServer, to perform 3D freehand ultrasound with Vicon and Qualisys systems.

Here are the attached files : Configfile_Server.zip

We already succeeded in :

• creating a OpenIGTLink server using Python that sends random quaternions into the port 18944 (file "my_server.py" attached in the zip). Let's call him "NexusServer" (later we will send the Vicon Nexus data from the rigidbody into this server)
• creating a OpenIGTLink server using PlusServer that receives data from the NexusServer (18944) and sends data into the port 18946 (config file "my_OpenIGTLinkTracker.xml"), to be read by 3D Slicer. Later, we want to use the PlusServer server to mix data from NexusServer and from the ultrasound, either Telemed or from a videograbber.
• reading the PlusServer data with 3D Slicer.

We confirm that, when we launch PlusServer server, we do have a client connection to our NexusServer. We also confirm that 3D Slicer connects to the PlusServer server, by displaying "ON", however we have no transform appearing in "IN".

We suspect that the data sent into PlusServer from the NexusServer are not in the right format.

Could you help us with the format of transform needed by PlusServer ?

Best regards, Aurélie

[lassoan]

You can see the error in the Slicer Python console:

[VTK] Received unknown device type POSITION, device=Tracker

This means that Slicer ignores POSITION messages. You can use TRANSFORM messages instead.

[AurelieSar]

Yes indeed thank you very much, we realized our error a few hours after. We now have something appearing in "IN", however it is not yet detected as a transform, we must have forgotten a parameter in the TRANSFORM MESSAGE setting in python.

[lassoan]

See example for sending transforms here: https://github.com/lassoan/pyigtl/blob/master/examples/example_tracked_image_server.py

[aaa34169]

thank for this reply. I am Aurelie's colleague I am not sure about the argument "device_name" of the TransformMessage Instance.

if i have the following the plusserver config :

<PlusConfiguration version="2.2">

  <DataCollection StartupDelaySec="1.0" >
    <DeviceSet 
      Name="Fabien - OpenIGTLink tracker connection (Probe, Reference)"
      Description="" 
    />

    <Device
      Id="TrackerDevice"
      Type="OpenIGTLinkTracker"
      MessageType="TRANSFORM"
      ServerAddress="127.0.0.1"
      ServerPort="18944"
      IgtlMessageCrcCheckEnabled="true"
      AcquisitionRate="30"
      LocalTimeOffset="0.0"
      TrackerInternalCoordinateSystemName="Reference"
      ToolReferenceFrame="Reference">
      <DataSources>
        <DataSource Type="Tool" Id="Tracker" />
      </DataSources>
      <OutputChannels>
        <OutputChannel Id="TrackerStream">
          <DataSource Id="Tracker" />
        </OutputChannel>
      </OutputChannels>
    </Device>

  </DataCollection>

  <PlusOpenIGTLinkServer
    MaxNumberOfIgtlMessagesToSend="1"
    MaxTimeSpentWithProcessingMs="50"
    ListeningPort="18946"
    SendValidTransformsOnly="TRUE"
    OutputChannelId="TrackerStream" >
    <DefaultClientInfo>
      <MessageTypes>
        <Message Type="TRANSFORM" />
      </MessageTypes>
      <TransformNames>
        <Transform Name="TrackerToReference" />
      </TransformNames>
    </DefaultClientInfo>
  </PlusOpenIGTLinkServer>

</PlusConfiguration>

I suspect the device_name should point the transform name ( ie TrackerToReference) and not an actual device

am i wrong ?

regards

Fabien

[lassoan]

Plus always uses the "(FromCoordinateSystem)To(To CoordinateSystem)" as device name. Device name is used as node name in Slicer.