Send customized data over OpenIGTLink

Support
1

Hi

Is it possible to send a customized polydata over OpenIGTLink. In an earlier version, I was able to send the data by setting the igtl::PolyDataMessage::Pointer and then sending the data by directly calling vtkMRMLIGTLConnectorNode::SendData to send the polydata message.

It looks like in the new version of OpenIGTLink, SendData method has been removed. Do I need to set the polydata to a vtkMRMLModelNode and then push the node over OpenIGTLink? Can you let me know how if there is an easier way of sending the customized polydata message.

Thanks
Priya

2

You can send the model by setting it as an output node and calling Modified() on it.

@Sunderlandkyl is there a way for one-time sending of a node (without setting it as an output node) in latest SlicerOpenIGTLink?

3

No, the only method that I can see currently is to call:

connectorNode.RegisterOutgoingMRMLNode(node)
connectorNode.PushNode(node)
connectorNode.UnregisterOutgoingMRMLNode(node)

I’ll take a look to see if I can add some additional methods to simplify one-off messages:

  • Send OpenIGTLink message directly
  • Send message from node without having to register/unregister the node
1 Like
4

I may be missing something here since it doesn’t look like it works. As a toy example, I tried to extract the polydata from a model and then send it over OpenIGTLink by creating a vtkMRMLModelNode and pushing the node. The code snippet is included below:

//Creating some dummy polydata
vtkPolyData* polyData = modelNode->GetPolyData();


// send the data
vtkSmartPointer<vtkMRMLModelNode> modelClientNode = vtkSmartPointer<vtkMRMLModelNode>::New();
modelClientNode->SetAndObservePolyData(polyData);
modelClientNode->Modified();
connectorNode->RegisterOutgoingMRMLNode(modelClientNode);
connectorNode->PushNode(modelClientNode);
connectorNode->UnregisterOutgoingMRMLNode(modelClientNode);

I don’t receive the polydata on the server side. Please let me know your suggestions.

Thanks
Priya

5

The model node needs to be added to the scene so that a node reference can be added to the connector node.

6

Thanks for your suggestion. I still seem to be getting the following error:

Unable to create vtkPolyData from incoming POLYDATA message. Failed to unpack the message

7

Interesting, I just tested with the latest stable and I was able to send a polydata between them.

What version of Slicer are you using?
Could you send me a “.vtk” for the polydata that gave the error.

8

I am using Slicer 4.13.0-2021-01-13. It occurs with every vtk model that I try to send. Not sure where the problem is.

In fact, even if I try to send the model from the OpenIGTLink module in Slicer (not programmatically), I run into the same problem with the following error:

Unable to create vtkPolyData from incoming POLYDATA message. Failed to unpack the message