Question about coordinates

[Boris]

Hello

I would like to ask several questions about coordinates:

(1) What are the units of coordinates in file provided by Biosemi?

(2) Why in Biosemi file r is taken as 100?

(3) How can I convert these coordinates to sLoreta an EEGLAB? Is origin of Biosemi provided coordinates the same as for sLoreta and EEGLAB?

Thanks

Boris

[Coen]

(1) What are the units of coordinates in file provided by Biosemi?

Choose any length unit you want, and then scale appropriately by selecting the proper value for the head radius (r)

(2) Why in Biosemi file r is taken as 100

Just to list easy-to-read numbers, choose your own head radius (r) depending on length unit and head head circumference (cap size).

(3) Is origin of Biosemi provided coordinates the same as for sLoreta and EEGLAB?

The origin location is fully explained in the file on http://www.biosemi.com/download/Cap_coords_all.xls

Best regards, Coen (BioSemi)

[iza]

Coen wrote:
> The origin location is fully explained in the file on
> http://www.biosemi.com/download/Cap_coords_all.xls

Hi,
Is it possible to find somewhere electrode coordinates for the system with 192 electrodes?
I see that there are no avaialbe in the file mentioned above


Best,

[Coen]

192 is a custom made special, probably a standard 160 plus 32 extra positions, no position file is available from BioSemi.

The 32 extra coordinates are quite easily calculated by yourself by extrapolation.

Best regards, Coen (BioSemi)