Fwd: Electric field measures generated by ROAST

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Yu (Andy) Huang

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Jun 30, 2019, 9:19:10 PM6/30/19
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---------- Forwarded message ---------
From: Yu (Andy) Huang <andypo...@gmail.com>
Date: Mon, Jun 17, 2019 at 8:24 AM
Subject: Re: Electric field measures generated by ROAST
To: Evans, Carys <carys...@ucl.ac.uk>


To get the normal vector at a given point on a local surface, first get the point cloud neighboring to that point, and then calculate the eigenvectors of this point cloud. The eigenvector corresponding to the smallest eigenvalue is the normal vector. Maybe this can help you  http://pointclouds.org/documentation/tutorials/normal_estimation.php

On Mon, Jun 17, 2019 at 7:01 AM Evans, Carys <carys...@ucl.ac.uk> wrote:
Hi Dr. Huang

Thank you for your email. If it's not too much trouble, could you explain in more detail how the normal component could be extracted from the data. I'm not sure I follow your instructions you provide.

Thanks again for your help.

Best wishes

Carys

From: Yu (Andy) Huang <andypo...@gmail.com>
Sent: 10 June 2019 23:41
To: Evans, Carys
Subject: Re: Electric field measures generated by ROAST
 
Hi Dr. Evans,

Unfortunately the normal component is not included. But you can calculate on your side: just do a dot product between the electric field vector and the normal vector at a given location. The normal vector can be computed using eigenvalue decomposition of the local point cloud, something like the PCA.

Hope this helps.

On Mon, Jun 10, 2019 at 6:04 AM Evans, Carys <carys...@ucl.ac.uk> wrote:
Dear Dr. Huang

I hope you are well. 

I had a quick question regarding the electric field information that is calculated by ROAST. According to the ReadMe, the following information is generated in a results.mat file and nifti images: voltage, electric field, electric field magnitude.

Do any of these results include the normal component of electric field? If not, would it be possible to extract this information from the data?

Many thanks

Carys Evans


------------------------------------------------------------------------

Dr. Carys Evans

Research Associate

Bestmann Lab: www.bestmannlab.com 

Department of Clinical and Movement Neurosciences

UCL Institute of Neurology

33 Queen Square, London, WC1N 3BG

Tel: 0203 4488 774


https://sites.google.com/site/carysevansresearch/ 



--
Yu (Andy) Huang, Ph.D.
Postdoc fellow at Dept. of Biomedical Engineering, City College of New York
Center for Discovery and Innovation, Rm. 3.320,


--
Yu (Andy) Huang, Ph.D.
Postdoc fellow at Dept. of Biomedical Engineering, City College of New York
Center for Discovery and Innovation, Rm. 3.320,


--
Yu (Andy) Huang, Ph.D.
Postdoc fellow at Dept. of Biomedical Engineering, City College of New York
Center for Discovery and Innovation, Rm. 3.320,
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