Receiving rigid body's markers location

[Avielb]

Hi,

We are using the NatNet 2.7 SDK and motive 1.8 in order to perform real-time 6DOF tracking of devices in our application.

In order to calibrate between rigid-body's coordinate system to device's coordinate system, we need to receive the relative position of the markers location to the rigid body center (as displayed in Motive).

By now, I saw that a rigidBody has a member named Markers but I it seems like it hold only 3 numbers (while I expected to see x,y,z for all my 5 markers)

How should we get this data?

Thanks,
Aviel

[Avielb]

Any ideas, someone?

[steven.andrews]

Hello Avielb,

Thank you for reaching out to us regarding your question. I apologize for the delay in getting you a response.

I do not believe the marker data is located under the rigid body. There is a MarkerSet data type that is separate from the RigidBody data type. The MarkerSet data contains the information for all identified markers, including position. You may want to look through this for the markers that are driving your rigid body.
http://www.optitrack.com/static/documen ... 0Guide.pdf

The NatNet SDK comes with several sample applications. If you look at the SimpleClient or SimpleClient3D examples, both of these should show how to retrieve the marker data.


I hope this information helps with your work. If you need anything else, please feel free to open a ticket with us at http://help.naturalpoint.com

Best regards,
Steven
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Steven Andrews
OptiTrack | Customer Support Engineer

[Hanowde]

Hi, everyone

I just want to ask if it is possible to get position data of single optitrack Marker?

If yes how should i do it better?

Thank your!

[steven.andrews]

Hello Hanowde,

It is possible to track the position of a single marker, but this has some inherent difficulties. Unlabeled markers are not identified, so if a marker is occluded and then reappears the system has no way of knowing the reappearing marker is the same as the previous. If you are streaming a single marker in realtime you may need to make the assumption that there is only one marker reconstructing at any time and that any new markers are the same as the previous.

If you are recording your data, it is possible to create a Marker Set in Edit Mode so that you can manually label the marker throughout the Take. If you do this and then stream the recorded Take, the marker ID will remain whatever name you have labeled it as.

I hope this information helps.

Cheers,
Steven
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Steven Andrews
OptiTrack | Customer Support Engineer

[Hanowde]

Hi, Steven

Thank your for your answer.

Your meant this is no way to get the position of a single marker from Motive to Unity?

Sorry for my bad understanding of your explaination...I have also tried to use MarkerSet to add different labels to singel marker, yes they have different labels but how could i get the position of them, because i dont see any data in the list, if i use the NatNetSample Applicartion --> pls see my images:

https://onedrive.live.com/redir?resid=9 ... hoto%2cpng

https://onedrive.live.com/redir?resid=9 ... hoto%2cpng

I need a solution and please help me.

Thanks.

[steven.andrews]

Hello Hanowde,

You can retrieve a single unlabeled marker from the realtime stream using the NatNet SDK. Markers that are not labeled are classified as "other markers." If you search our documentation for this, you should find some information on how to retrieve them.
http://www.optitrack.com/static/documen ... 0Guide.pdf

The thing to be aware of regarding unidentified markers is that their IDs can change. This is because an unidentified marker cannot be recognized as the same marker if the system loses track of it. If you only have one marker being reconstructed, however, you can keep checking the other markers list and assuming the one marker there is the same marker.

It looks like you are currently using NatNet 2.6. In order to access unlabeled markers, you may need to use the latest version, NatNet 2.9. Please note that the sampleclient that ships with the latest version of the SDK includes code showing how to retrieve unlabeled marker data. This code is commented out for efficiency, however, so the sampleclient exes that ship with the SDK will not display unlabeled markers unless you recompile the code with that section of code uncommented.

I hope this information proves to be useful. If we can do anything else to help, please feel free to reach out to us.

Best regards,
Steven
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Steven Andrews
OptiTrack | Customer Support Engineer