Bertec FP origin and V3D

[Justus Ortega]

We recently purchased a Bertec Fit5 treadmill. We collect our data in Vicon Nexus and analyze data using Visual 3D. Although the force vector appear correct in Vicon Nexus, when the C3D file is brought into Visual 3D, the force vector is out in front of the force place. Has anyone run into this problem and found a way to correct it permanently (in Vicon or Visual 3D). the folks at Visual 3D suggest "just add a Z-Origin offset of +0.001". However, this did not do much at all. Only by changing the Y_origin form Negative to positive for both plates AND changing the X-origin for FP 1 from Positive to Negative (279 to -279) and changing the X-origin for FP 2 from Negative to Positive (-279 to 279)....doe sit look correct. Any Help would be greatly appreciated. Her is the documentation from the V3D Wiki ... https://wiki.has-motion.com/FP_ORIGIN

[Justus Ortega]

Problem solved. For anyone using Bertec Fit5+ Vicon nexus (data Collection)+ Visual 3D (analysis), you should Change the Z-Origin offset from 0 to 0.0001. The issue really seems to stem from the way the origin data is stored and trasnfered between Bertec to Vicon to Visual 3D. As per the Visual 3D Wiki site.....
"Bertec uses an ORIGIN of (279.4,889,0) and (-279.4,889,0), which is a nuisance for Vicon users because Vicon stores the ORIGIN parameter incorrectly.

For all other platforms, Visual3D can guess that the ORIGIN was stored incorrectly by checking the sign of the z-component of the ORIGIN.

The c3d format requires the z-parameter to be negative. If the ORIGIN is stored with a positive value, Visual3D multiplies all 3 components of the ORIGIN by -1. If the z-component is negative, Visual3D cannot make a decision. Vicon users with Bertec treadmills, should use a very small z-component 0.0001 so that Visual3D knows to multiply by -1."

I have not verified that "Viconstores the ORIGIN parameter incorrectly". But the solution work!