Mike,

The Fig 9.4 of your book “Analyzing Neural Time Series Data” used a EEG dataset sampleEEGdata.mat. After loading it into Matlab, it created a structure EEG.

I need help to confirm the coordinate system used in EEG.chanlocs. My current understanding is the following

- There are 2 coordinate systems: polar and cartesian
- The origins of both systems are at the center of the head (not on the surface)
- X axis points to the nose
- Y axis points to the left ear
- Z axis points up (top of scalp)
- Theta is the rotation around the Z axis following standard right hand rule, and the nose has theta=0, left ear = 90 degree
- Phi is the angle measured from the XY plan, + direction is towards the scalp, - direction is towards the feet
- What is the measurement unit for ‘radius’? e.g. cm, mm, inch etc
- What is the measurement unit for X, Y, Z?
- what is the measurement unit for ‘sph_radius’?

If there is a good documentation source, please share.

Regards,

-Larry