# OpenIGTIF Trajectory Message

**URL:** <https://discourse.slicer.org/t/openigtif-trajectory-message/8280>\
**Category:** Support\
**Created:** [September 3, 2019, 6:21pm UTC](https://discourse.slicer.org/t/openigtif-trajectory-message/8280 "2019-09-03T18:21:07Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![burnhamd](https://avatars.discourse-cdn.com/v4/letter/b/5fc32e/32.png) [@burnhamd](https://discourse.slicer.org/u/burnhamd)\
**Post date:** [September 3, 2019, 6:21pm UTC](https://discourse.slicer.org/t/openigtif-trajectory-message/8280/1 "2019-09-03T18:21:07Z")

</div>

Does the OpenIGTIF extension have support to receive and send trajectory messages? I cant seem to find mention of it.

---

<div class="post-metadata">

**Author:** ![burnhamd](https://avatars.discourse-cdn.com/v4/letter/b/5fc32e/32.png) [@burnhamd](https://discourse.slicer.org/u/burnhamd)\
**Post date:** [September 4, 2019, 2:31pm UTC](https://discourse.slicer.org/t/openigtif-trajectory-message/8280/2 "2019-09-04T14:31:37Z")

</div>

I am attempting to send a trajectory using a annotation. I placed a ruler annotation in the scene. But when I try to add this to my connector node, slicer crashes without an error message.

---

<div class="post-metadata">

**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [September 4, 2019, 2:48pm UTC](https://discourse.slicer.org/t/openigtif-trajectory-message/8280/3 "2019-09-04T14:48:07Z")

</div>

Which Slicer version do you use?

@Sunderlandkyl There seems to be a [converter for ruler-\>trajectory](https://github.com/openigtlink/OpenIGTLinkIF/blob/master/MRML/vtkIGTLToMRMLTrajectory.cxx) could you have a look why it may fail?

---

<div class="post-metadata">

**Author:** ![Sunderlandkyl](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sunderlandkyl/32/79987_2.png) [@Sunderlandkyl](https://discourse.slicer.org/u/Sunderlandkyl)\
**Post date:** [September 4, 2019, 3:11pm UTC](https://discourse.slicer.org/t/openigtif-trajectory-message/8280/4 "2019-09-04T15:11:11Z")

</div>

That’s the old repository, there is no such converter in [SlicerOpenIGTLink](https://github.com/openigtlink/SlicerOpenIGTLink), or in [OpenIGTLinkIO](https://github.com/IGSIO/OpenIGTLinkIO/tree/master/Converter).

.

---

<div class="post-metadata">

**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [September 4, 2019, 3:18pm UTC](https://discourse.slicer.org/t/openigtif-trajectory-message/8280/5 "2019-09-04T15:18:13Z")

</div>

@burnhamd Since trajectory message is not supported now, I would recommend to use transform message instead. You can compute a transform from position of the two endpoints of the ruler.

---

<div class="post-metadata">

**Author:** ![burnhamd](https://avatars.discourse-cdn.com/v4/letter/b/5fc32e/32.png) [@burnhamd](https://discourse.slicer.org/u/burnhamd)\
**Post date:** [September 4, 2019, 3:24pm UTC](https://discourse.slicer.org/t/openigtif-trajectory-message/8280/6 "2019-09-04T15:24:00Z")

</div>

I decided to use the string message and send the same data that way for now. This approach is working well. I assume it is a bug then that the annotation shows up in the available data list for sending of MRMLNodes? Seems that this should be removed from the UI at least to avoid crashes when someone attempts to send them.

Thanks for your help!

---

<div class="post-metadata">

**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [September 4, 2019, 3:29pm UTC](https://discourse.slicer.org/t/openigtif-trajectory-message/8280/7 "2019-09-04T15:29:35Z")

</div>

I agree, we should not show nodes that cannot be transferred (or at least not crash but log an error). I’ve added a ticket to track this: [https://github.com/openigtlink/SlicerOpenIGTLink/issues/96](https://github.com/openigtlink/SlicerOpenIGTLink/issues/96)