[Eeglablist] [EXTERNAL] Re: get_chanlocs

Eriksen, Jeff :LGS Neurodiagnostics JEriksen at LHS.ORG
Fri Dec 27 16:00:40 PST 2019


I noticed this on the Apple page for the Occipital Scanner 1.11:

Don't Get the Mark II  ,  10/11/2019
Cannot Recommend
If you are planning on getting the mark II for this app, Don’t do it. The mark II structure sensor just doesn’t work. Tried on multiple devices and it just doesn’t hold a charge. Looking at their return policy, once you open the product you can’t return it. Basically I am stuck with a $400 door stop.

Soooooooooooo, has anyone out there used the Mark II yet with the Scanner app?


From: Seyed Yahya Shirazi <shirazi at ieee.org>
Sent: Friday, December 27, 2019 2:02 PM
To: eeglablist at sccn.ucsd.edu
Cc: Eriksen, Jeff :LGS Neurodiagnostics <JEriksen at LHS.ORG>; Andrew Engell <engella at kenyon.edu>
Subject: [EXTERNAL] Re: get_chanlocs

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Dear Jeff and Andrew,

Glad to hear there is more and more interest in 3D scanning and EEG digitization/positioning in general. We do digitize EEG electrode locations using Structure Sensor and iPad Pro 10.5" in our lab.
Our recent paper compared 3D scanning with Zebris and motion capture, and Structure performed very well both in digitization reliability and also consistency in finding the same source locations (see https://www.ncbi.nlm.nih.gov/pubmed/31787866<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpubmed%2F31787866&data=02%7C01%7CJEriksen%40lhs.org%7C187a103e2348419178fc08d78b18781c%7C3683988d7d404338bf200b5dd13f4301%7C0%7C0%7C637130809539475855&sdata=6wSPMvIoap0QhW3wBLvmcsLoSL31DIUUwiO5lcqGclg%3D&reserved=0>).
Electrode digitization with a 3D scanner has two main steps: 1- scanning the head 2- marking the electrodes and fiducial locations in a software (here MATLAB). I would say after learning how to use the scanner, each step takes about 10 minutes with a 128-channel BioSemi ActiveTwo system. Gaia Taberna (from Dr. Manitini's lab in KU Leuven) also created a toolbox for automatically marking the electrodes, and they had the EGI system (see: https://www.ncbi.nlm.nih.gov/pubmed/31492919<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpubmed%2F31492919&data=02%7C01%7CJEriksen%40lhs.org%7C187a103e2348419178fc08d78b18781c%7C3683988d7d404338bf200b5dd13f4301%7C0%7C0%7C637130809539475855&sdata=AxjkwlmjmAfFrffRIe0JGgAX%2BiQ02CWeLg6NN9Hc4%2FA%3D&reserved=0>). I have not tried the automatic approach yet because 10 minutes is not a long time to do mark up the scan.
The original (NOT the core) scanner works with my iPad Air A2152 (it has the same chassis as iPad Pro 10.5 A1701). I am not sure about the earlier iPads, but I think as long as the Structure.io website claims the scanner supports that model, you are good to go. However, make sure that you have the bracket (adapter) to attach the scanner to the iPad (I checked strucutre.io<https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fstrucutre.io%2F&data=02%7C01%7CJEriksen%40lhs.org%7C187a103e2348419178fc08d78b18781c%7C3683988d7d404338bf200b5dd13f4301%7C0%7C0%7C637130809539485812&sdata=GEOlNtC5QyIe35Ki1IzTm7IwABc54xlDeQHWJxibZOg%3D&reserved=0>, and it seems they don't offer a bracket for A1474). Structure scanner MarkII is just a better scanner with better resolution. The core version is supposedly the standalone scanner with a tripod, so I don't think that's the option you want.
You only need the Scanner app from Apple AppStore (https://apps.apple.com/us/app/scanner-structure-sdk/id891169722<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fapps.apple.com%2Fus%2Fapp%2Fscanner-structure-sdk%2Fid891169722&data=02%7C01%7CJEriksen%40lhs.org%7C187a103e2348419178fc08d78b18781c%7C3683988d7d404338bf200b5dd13f4301%7C0%7C0%7C637130809539485812&sdata=bOfgkAajDOGuf%2FzcPoMm6rlzSJ1cPNtlhhuiIeJNovE%3D&reserved=0>) to do the scanning. The app is free and would ask you to install its calibrator app (also free) if you are scanning for the first time. The only downside of this app is that it can't store the scan on the iPad and only would send it via email, so you need an internet connection. Both EEGLAB and FieldTrip toolbox can read outputs of the Scanner app after you unzip it from the email attachment (see our pipeline, based on FieldTrip, here: https://github.com/neuromechanist/eLocs<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fneuromechanist%2FeLocs&data=02%7C01%7CJEriksen%40lhs.org%7C187a103e2348419178fc08d78b18781c%7C3683988d7d404338bf200b5dd13f4301%7C0%7C0%7C637130809539495769&sdata=HEYK%2BxPHrqvPc8ocv7%2BynglRDlZAkaWdKAvcUFkjJRQ%3D&reserved=0>).
The Structure sensor has its limitations too. With the original model that we are currently using, the scanner is susceptible to the lighting conditions, so we only do the digitization in a specific spot in our lab to make sure that they are similar. Also, sometimes the scanned point cloud and the color image that should be overlayed to the point cloud do not match, or the color image is not clear. So we always check the results on the iPad to make sure that we have the right quality color image, and the image matches the point cloud. As I said earlier, using a 3D scanner for EEG electrode digitization has a learning curve, but once you get used to the process, it just takes 10 minutes to scan and another 10 minutes to mark up the locations in MATLAB.

Please do not hesitate to contact me if I can be of more assistance.

Seyed Yahya Shirazi
Ph.D. Candidate, BRaIN Lab
University of Central Florida

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