Cortex Motion Analysis

[Lynsey Northeast]

Hi

I am just starting a PhD using a camera system that is new to our laboratory. We have a 10 Camera Owl motion analysis system (Santa Rosa, California).

In some of my reading around this I have found that researchers are using other software programmes such as Matlab for their data analysis.

Just wondered what peoples thoughts are on using the cortex software for the analysis or would you advise using a different programme.

Many Thanks

[Josh Baxter]

Re: Cortex Motion Analysis

Hi Lynsey,

Could you give us some more details about what you'll be using the cameras for? What types of motions, are you interested in performing some inverse dynamics or just kinematics? do you have analog signals like force plates, strain gauges, EMG, etc?

Cortex does have a few full body marker sets built in with the scripting done for you. However, if you are interested in very specific tasks it will most likely be easier to use MATLAB or something like Visual 3D.

MATLAB has excellent documentation, while the Cortex scripting language is a bit more difficult to understand and does not have the best documentation.

Josh

[Lynsey Northeast]

Re: Cortex Motion Analysis

Hi Josh,

Thanks for your response.

I'll be looking at whole body motion during simulated ankle inversion using a modified Cleveland clinic marker set with a detailed foot model. I will also be recording EMG.

I don't have any experience working with MATLAB is this something that is relatively easy to learn?

Thanks
Lynsey

[Ton van den Bogert]

Re: Cortex Motion Analysis

If your marker set can be interpreted as having three or more markers on each body segment, you can use the KineMat toolbox to calculate 3D joint kinematics. The toolbox will take care of all the math. This still requires that you write Matlab code that imports your marker trajectories, executes the KineMat functions, and displays or exports the results.

KineMat can be found at http://isbweb.org/software/movanal/kinemat/

If you have no experience with Matlab you will need to invest some time learning it. But that's something you need to do anyway if you are doing a PhD in biomechanics.

Like Josh, I would favor doing this project with Matlab. For three reasons: (a) you learn more, (b) you are not limited by what is offered by a commercial software system, and (c) you will be more productive, after an initial time investment. Matlab will let you script everything. My goal is always to have a Matlab script that performs all processing from raw data to the Figures that go into a publication. That script is then also the complete documentation of what you did with the data.

Ton van den Bogert
Department of Mechanical Engineering
Cleveland State University

[Gary Scheirman]

Re: Cortex Motion Analysis

Hi Lynsey,

Cortex is much more than a data collection program. There are optional software modules (called Skeleton Builder and KinTools RT) that would permit you to set up custom kinematic computations (including abd/adduction, int/external rotation and flex/extension angles) and kinetic calculations using inverse dynamics in real-time or in post. These have a graphical interface for setting up the calculations and do not require any understanding of the Sky scripting language mentioned by Josh. Sky has hundreds of functions for generating specific computations or processes for customizing your workflow and data generation. There are example Sky scripts with documentation as well as video tutorials available from our tech support team. If you are interested, Tech Support can also send you written materials about them.

In addition, Motion Analysis Corp. has data export code for Matlab, Visual 3D, Labview and Excel.

Sincerely,

Gary Scheirman

[Tom Kernozek]

Re: Cortex Motion Analysis

Hi Lindsey,
We use the MotionMonitor software also with our MAC camera system. Originally we used The MotionMonitor or Visual 3d for importing and analyzing C3D files for kinematic and kinetic data analysis. We recently added the real-time capabilities with the MotionMonitor which allows us to stream marker data directly from Cortex. This software has given us the flexibility to use any marker set or rigid body clusters and all raw or processed data is easily accessible for output - no programming efforts are needed. The real-time capability has added a large time-saving benefit to our lab and have immediate playback of the trial with processed data displayed. Here's their website: www.TheMotionMonitor.com

Tom