connection between OpenVibe

[yannick]

Hi Openvibers,

I have a question for you, how it's possible to connect Openvibe with others applications or software?
For example, i want to collect informations about hand movments to move a virtual ball on my pc.
But i don't understand how it's possible ? Because when i have my outputs classifier processor " classification state", i don't know how to use it to move my ball.
What's kind of connections are possible? (Bus, socket or .....).
Thanks

[yrenard]

Dear Yannick,

for now, we are using the VRPN library which is used to abstract VR devices. You will find VRPN boxes under the VRPN folder in the designer.

More documentation can be found on the VRPN Analog Server page and the VRPN Button Server page.

Hope this helps,
Best regards,
Yann

[yannick]

Sorry, but i don't understand how to use VRPN button server.
Do you have an exemple where this box is used? and VRPN server to?

Thanks

[yrenard]

Dear yannick,

unfortunately, I don't have a simple VRPN example. This is quite a frequently asked question so I guess I should add a sample scenario in the repository that exposes some data thanks to the VRPN boxes and a sample program that gets its data from it.

I suggest you read this discussion I had in the past few weeks with another user. Tell me if it helps.

Yann

[yannick]

Thanks yann for your helps.
But i read a lot of things on internet about vrpn server etc...
I would like to know how i can listen a vrpn message if i have a vrpn server in my scenario with a another applications.
Do you know an application that allow it?

[yrenard]

Dear yannick,

the message I previously pointed out has sample code on how to connect to a VRPN server.

If you don't have programming knowledge or just don't want to write your own application, just know that most of the commercial VR engines such as 3DVia Virtools or Quest3D are able to get data from VRPN.

Can you explain us what you want to do with OpenViBE so I can point you to the right direction ?

Yann

[yannick]

In fact, i want to move a camera in a virtual world with brain waves.
For that, i want to use an EEG heap, openvibe will to do the acquisition of these signals, make a transformation( extraction, classifcation....) and Openvibe classifier processor's outputs give me the two class "right" and "left".
As the consequence i want to move the camera "on the right" and "on the left".
Do you understand?
That's all.

[lbonnet]

Hello yannick, welcome on board !

I join this topic because I am currently developping a new version of the tie-fighter and handball demonstrator for openvibe, based solely one the 3D rendering engine OGRE3D. Both demonstrator use motor imagery: the tie-fighter moves up after movement of the feet, and the ball moves right and left when moving right and left hand.

On the openvibe side, the scenarios use Analog VRPN server and Button VRPN Server box, for a unique peripheral named openvibe-vrpn@localhost.

We can imagine a scenario where the Button server is configured with 2 buttons : "Right" and "Left", that triggers when the server box receive the corresponding stimulations (given by a classifier processor).

The VR application then received VRPN button state that says "Right"/"Left" button is ON/OFF. Then we can start a visual feedback in the VR application, according to that states.

My VR application uses an abstract VRPN peripheric that can connect to at most 2 VRPN servers (1 Analog and 1 Button). But I had to write my own C++ class for this peripheric. As you will find in the topic that Yann pointed, the code is not very complicated. However if you are not a programmer it may be difficult to understand.

So I guess the question is how do you want to realize your application ?
If you're ready to put your hands in c++ code, we will help you for sure


Laurent-

[yannick]

Hi,

Thanks for your attention, in fact i used virtools for my 3D environment.
In my application, i want to send data to virtools.
The only choice is to use vrpn protocol, but actually i can't send data to virtools.

I don't understand why , in fact i use for testing the protocol the scenario named "motor-imagery-bci-3online".
I added a analog vrpn server after classifier processor to send data to virtools.
But i don't understand why vrpn client in virtools doesn't receive data?

Thanks

[yannick]

Moreover i would like top know how analog serve send information on the network.
Because i give the name of my virtools application but nothing.

[yrenard]

Dear yannick,

before trying to connect to Virtools, you should check that OpenViBE is actually sending something. For this to be done, you should try the command line test program that comes with VRPN. If you don't have it available, I can compile / send it to you tomorow (and I guess I should put it in the release )

If this works, then the problem is about your configuration in Virtools. Check the VR Pack user manual to check if everything is OK. I may assist you if needed but I prefer the IRC channel for this as I don't have Virtools available and it's been a few years since I last used it !

If it does not work, then you should check in this order :

• - that the name of the device you entered in openvibe is the same as the name of the device you entered on the client side
  - that the name of the host is correct (if not using a single machine)
  - that your firewall is not blocking anything (we had to disable a few things in windows firewall in the past... In the worst case, it's even possible to configure an SSH tunnel on another machine with you don't have admin rights)

Hope this helps,
Yann

[yannick]

thank you for your attention. You can compile your program and send me to check if openvibe send data on the network.
After that i could see exactly where i am in this situation.

I wait your program with happyness.



All the best

[yrenard]

Dear yannick,

here is the sample program. For your information, you can find its sources from the standard VRPN release 07.13 (It should still be present in more recent releases).

You should use it in a console this way :

Code: Select all

vrpn_print_devices peripheral_name@host_name

e.g.

Code: Select all

vrpn_print_devices openvibe-vrpn@localhost

You should read the analog / button status as they change in time.

Tell me if it works. If it does not, please dump the console messages so I can see what happens.

Yann

[yannick]

Thank you for your help, unfornately the vrpn_print_devices doesn't work.
But i have an information from OPENVIBE DEISGNER, i wish it can help you to help me.

Thanks

[yrenard]

Dear yannick,

what do you mean doesn't work ?

The snapshot you sent is interesting. It seems there is a version incompatibility between the VRPN version used by OpenViBE and the VRPN version used on the client side. Is it Virtools trying to connect ? If this is the case, we'll have to consider compiling the VRPN plugins of OpenViBE with an older version of the VRPN library (version 06.07 according to the message).

Waiting for your feedback,
Yann