Hi, I have got it working with the following:
// create data representation and add it to render view
pqDataRepresentation *drep = builder->createDataRepresentation(pipelineSource->getOutputPort(0), view);
auto dProxy = drep->getProxy();
vtkSMPropertyHelper(dProxy, "Representation").Set("Volume");
// use color and opacity from original data
vtkSMPropertyHelper(dProxy, "UseSeparateColorMap").Set(1);
vtkSMPVRepresentationProxy::SetScalarColoring(dProxy, "MetaImage", vtkDataObject::POINT);
vtkSMPVRepresentationProxy::RescaleTransferFunctionToDataRange(dProxy, false, false);
Thanks