forums.naturalpoint.com

Discussion and Support for the OptiTrack, SmartNav and TrackIR brands by NaturalPoint

how to obtain joint angle from BVH ARENA/

by Maryam Alzawahreh » Sat Nov 21, 2015 1:09 pm

Hi,
Through reading in the forum I read that I can obtain joint angles data from ARENA by exporting as BVH,, would you tell me what exactly to do with the BVH file to get the joint angles please? since am new to the system and i started taking takes and would want to get as much useful biomechanic parameters as possible

Another issue that I can't understand is when I export the a BVH file and open it on excel it has some written comments then a 21 data columns with all the frames rows,, what are those 21 columns for they seem to be distances X Y Z or something?

Thank you
Eng.Maryam Alzawahreh
Hashemite University
Maryam Alzawahreh
 
Posts: 2
Joined: Sat Nov 21, 2015 2:11 am

by steven.andrews » Wed Nov 25, 2015 10:30 am

Hello Maryam Alzawahreh,

Thank you for reaching out to us regarding your questions.
Our BVH should be pretty standard to the BVH format. There is a HIERARCHY section that describes the skeleton hierarchy, and MOTION section that describes the XYZ position of the root joint(hip) and rotation angles of all joints.
BVH is a text file so it can be viewed by any text editor. We are not sure if excel will display all of the data in the file, however.

Arena is one of our oldest, and less familiar, pieces of software and we have since expanded on the capabilities. If you are able to upgrade to Motive, you can take full advantage of the improved data quality and exports. Motive allows you to export CSV files, which often provide more information and prove to be more useful.

I hope this information helps you with your understanding of the BVH format. If you require any further assistance, please feel free to open a support ticket with us at help.naturalpoint.com

Best regards,
Steven
--
Steven Andrews
OptiTrack | Customer Support Engineer
steven.andrews
NaturalPoint Employee
NaturalPoint Employee
 
Posts: 366
Joined: Mon Jan 19, 2015 11:52 am

by Maryam Alzawahreh » Sun Nov 29, 2015 2:43 am

Hi,
thank you for your reply,,
yes we brought motive along with a new 12 cameras to our new lab but still didn't install them waiting for some university permissions,,
so my supervisor and I don't want to waste time and to take advantage of everything in ARENA,, so,,
I want to ask you please about what you said (rotation angles of all joints), what joints and what's their order corresponding the data columns in the sheet? I only found the 34 marker names which doesn't represent human body joints.

thank you
Maryam Alzawahreh
 
Posts: 2
Joined: Sat Nov 21, 2015 2:11 am

by steven.andrews » Wed Dec 02, 2015 10:29 am

Hi Maryam Alzawahreh,

Could you please open a ticket with us at help.naturalpoint.com?
I would like to receive a copy of your BVH so that I can see what you are dealing with.

Cheers,
Steven
--
Steven Andrews
OptiTrack | Customer Support Engineer
steven.andrews
NaturalPoint Employee
NaturalPoint Employee
 
Posts: 366
Joined: Mon Jan 19, 2015 11:52 am

by steven.andrews » Tue Dec 08, 2015 11:37 am

Hello Maryam,

I wanted to follow up with some additional information I hope will help you with the BVH.

Attached is a bvh file exported from Arena. This is standard format, with hierarchy section describing the skeleton structure and motion section describing position or rotations of those joints.

The bvh specs can be found online at:
http://research.cs.wisc.edu/graphics/Courses/cs-838-1999/Jeff/BVH.html

Cheers,
Steven
--
Steven Andrews
OptiTrack | Customer Support Engineer
Attachments
test.bvh
(335.92 KiB) Downloaded 206 times
steven.andrews
NaturalPoint Employee
NaturalPoint Employee
 
Posts: 366
Joined: Mon Jan 19, 2015 11:52 am


Return to ARENA & Expression