BodyBuilder script

[Jennifer Perry]

Hello all,

I am attempting to write some code in bodybuilder for a foot modeling project and am running into some issues. (I have never written anything in BB before). What we are doing is using 3-marker clusters on the feet and then taking static pointing trials in which we use a 2-marker wand to point to anatomical landmarks. How does one go about writing a BB script such that it will create the dummy marker according to the pointing trial and then recreate that marker (using cluster as reference) during dynamic trials?

Any help would be greatly appreciated!

[Kyle Chadwick]

Re: BodyBuilder script

Hi Jennifer,

I actually had a similar problem not too long ago, where we wanted script to place the a virtual marker where the 2-marker wand is pointing. What we have is the "Davis Wand" which compresses so that the 2 markers move closer to each other when you are pressing where you want the virtual marker. I had trouble trying to write out this function using the bodybuilder code and instead wrote that part in Matlab (which can also be run in the Nexus pipeline). It works, but can be a bit clunky, since you need to wait for Vicon to open up Matlab and execute the script (and you need to have Matlab). I'd be interested if anyone has been able to write BB code to do the whole operation.

If you're using the Davis Wand too and Matlab is a feasible option, let me know and I can share our code.

Kyle Chadwick
Motion Lab Engineer
Children's Hospital Los Angeles

[Tim Wrigley]

Re: BodyBuilder script

It's relatively straightforward. BB has inbuilt functions (using * and /) for global/local transformations that make it easy.

Conceptually, without giving you exact syntax, this is the process:

In the static trial ...
1. Having captured the pointer markers, calculate the projected tip location in the global coordinate system (from the known pointer geometry).
2. Construct a coordinate system from the 3 cluster markers (hopefully relatively rigid).
3. Express the global pointer tip location (from 1) as local coordinates in the cluster coordinate system (using / syntax).
4. Save those local coordinates to the MP/VSK file (via PARAM command and using $ syntax).

In the dynamic trial ...
1. Construct the cluster coordinate system again (in exactly the same way).
2. Retrieve the local pointer tip coordinates from the MP/VSK (simply by referring to them with $ syntax).
3. Re-express the local tip coordinates as global (using * syntax).
4. Save global coordinates via OUTPUT.

Hope that gives you enough to go on.

Tim Wrigley
University of Melbourne

[Paulo Lucareli]

Re: BodyBuilder script

Dear Jeniffer,

I've been using this pointer technique to create LASI, RASI markers and one cluster with 3 markers on LPSI,RPSI and Sacrum in BB.

Is you need I can send it to you and you just have to change the markers name and the markers pointer distance.

Best

Paulo Lucareli
Universidade Nove de Julho
Brazil

[Jennifer Perry]

Re: BodyBuilder script

Dear Jeniffer,

I've been using this pointer technique to create LASI, RASI markers and one cluster with 3 markers on LPSI,RPSI and Sacrum in BB.

Is you need I can send it to you and you just have to change the markers name and the markers pointer distance.

Best

Paulo Lucareli
Universidade Nove de Julho
Brazil

Paulo,

That would be amazing to see your script for the pointer technique. I am assuming it is two scripts, one to define the virtual marker and one to reproduce it. If you could send them to jap6rc@virginia.edu that would be a huge help.

Thanks,
Jennifer

[Jennifer Perry]

Re: BodyBuilder script

Thank you, Tim! That conceptual layout helped clear the fog for me on where I was going wrong.

Thanks,
Jennifer

[Federica Corona]

Re: BodyBuilder script

Paulo,

That would be amazing to see your script for the pointer technique. I am assuming it is two scripts, one to define the virtual marker and one to reproduce it. If you could send them to jap6rc@virginia.edu that would be a huge help.

Thanks,
Jennifer

Dear Paulo,

if it is possible, for me too it would be an amazing help to see your pointer and cluster technique. I'm trying to write something in BB, but I've never used before. Please if it's possible, could you send its to corona.federic@gmail.com

Thanks,
Federica

[Federica Corona]

Re: BodyBuilder script

Dear Jeniffer,

I've been using this pointer technique to create LASI, RASI markers and one cluster with 3 markers on LPSI,RPSI and Sacrum in BB.

Is you need I can send it to you and you just have to change the markers name and the markers pointer distance.

Best

Paulo Lucareli
Universidade Nove de Julho
Brazil

Dear Paulo,

if it's possible, could you send to corona.federic@gmail.com your pointer and cluster technique? I'm trying to write my first code in BB with more doubts.

Thank you,
Federica

[Tim Blackmore]

Re: BodyBuilder script

Federica,

If you are using Vicon Nexus with your BodyLangauge scripts then here is an example of what Tim Wrigley has outlined above.


{*-------------------------Pointer-------------------------*}


Global = [{0,0,0},{1,0,0},{0,0,1},xyz]


{*---------------Model---------------*}
{*Optional points*}
OptionalPoints(PM)


{*General*}
tempSeg = [STER,CLAV-STER,STER-T10,xzy]


{*Static trials*}
If $Static==1
$%PMcalc = PM/tempSeg
PARAM ($%PMcalc)
EndIf

{*Replace PM*}
If $Static==0
PM = $%PMcalc*tempSeg
EndIf


OUTPUT(PM)


If you were to run this through Vicon Nexus using the 'Run Static BodyLanguage Model' pipeline command, then your pointer marker will be saved to the VSK relative to the tempSeg segment. Then when you run the same script again using the 'Run Dynamic BodyLanguage Model' pipeline command, your pointer marker will be recreated. It is important to use these pipeline commands as they align with the ''If $Static ==1" and "If $Static ==0" in the script.

A couple of things to note:

1. This script needs to be saved as a .mod file.
2. Create an empty text file, of the same name with the extension .mp. Ensure it is stored in the same location as the .mod file.
3. This is an example, the chosen markers do not really suit the application, but should give you a framework to work from.


Good luck.

Tim Blackmore

[Bruce MacWilliams]

Re: BodyBuilder script

Hello all,

I am attempting to write some code in bodybuilder for a foot modeling project and am running into some issues. (I have never written anything in BB before). What we are doing is using 3-marker clusters on the feet and then taking static pointing trials in which we use a 2-marker wand to point to anatomical landmarks. How does one go about writing a BB script such that it will create the dummy marker according to the pointing trial and then recreate that marker (using cluster as reference) during dynamic trials?

Any help would be greatly appreciated!

You need to use the PARAM() statement to write expressions to the MP file which can then be used by dynamic files. Also use conditional code such as If Static = 1 or have separate scripts for dynamic and static trials.

[Paulo Lucareli]

Re: BodyBuilder script

Dear Paulo,

if it is possible, for me too it would be an amazing help to see your pointer and cluster technique. I'm trying to write something in BB, but I've never used before. Please if it's possible, could you send its to corona.federic@gmail.com

Thanks,
Federica

Hi Federica,

I'll send to you in you email.

Best

Paulo

[Federica Corona]

Re: BodyBuilder script

Hi Federica,

I'll send to you in you email.

Best

Paulo

Thanks a lot Paulo.

Best,
Federica