Hi Renato,

Interesting question.

Considering a particular electrical event of the heart under investigation, I would say the origin point of the VCG, as you stated, depends on, basically, two conditions:

i) how you define both the onset and the offset of that particular electrical event, and

ii) which event is under investigation. 

Consider the event under investigation is the ventricular activation. It is, thus, necessary to define its onset and its offset. To accomplish this task, it is easier to recur to the one dimension ECG to define those fiducial points first (QRS complex onset and offset) and then to transport them onto the VCG, geometrically. 

There are several methods that you can apply to detected those fiducial points: cartesian curvature, noise analysis, geometric approach.

Take a look at this reference. 

1)  https://www.researchgate.net/publication/265678033_Robust_Derivative-Based_Method_to_Determine_Filtered_QRS_Limits_in_High_Resolution_Electrocardiography.

Let me know if it was helpful.

Best regards.

Peace and blessings.

Article Robust Derivative-Based Method to Determine Filtered QRS Lim...

Thank you for your answer. It will be very helpful. I was confusing  when I read some references of Tereshchenko et al. that defining the origin point like “ the mid-point along the line connecting the two points that were closest in space but significantly separated in time”I was confusing  when I read some references of Tereshchenko et al. that defining the origin point like “ the mid-point along the line connecting the two points that were closest in space but significantly separated in time”