Yes I tried ! but if I select the vtr imported object the stream tracer is not available as filter !
this is th reason why I’m asking for the correct procedure … if for example I create a probe locator from the main object then the stream tracer is clickable (available) but I would like to use the filter “stream tracer from custom area” in order to create stream tracer from the centre of poly_data representing the polymer ! May you help me about ?