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GeoScan Sensor Digitization - Use Instructions and Helpful Tips
The GeoScan Sensor Digitization device is a handheld solution for 3D electrode position registration. The GeoScan device was introduced as a fast and minimally-invasive solution for electrode sensor registration. The 3D electrode sensor cloud is in a .txt format, and can be exported via GPS solver software as .xml, .sfp, .elp, or .nsi formats for use with the GeoSource 3.1 software individual head model generation workflow or other software including Besa or Matlab. Magstim EGI does not provide support for use of GeoScan files with 3rd party software. Please contact the software developers directly should you have any questions. Do note, the GeoScan is not optimized for use with infants. The tested and recommended workflow was designed for use with adult participants, but infant and premature infant nets are still built with Nikkalite labels.
IMPORTANT NOTE: The GeoScan device has been deemed end of life (EOL) by the manufacturer. Sales and servicing of the GeoScan device are limited, and no further software will be developed or tested. For pricing and more information about the GeoScan Device, please contact the Magstim EGI sales team. Techincal support regarding the use of the GeoScan device will continue as possible. Please contact the Magstim EGI Support Team with any questions.
Use of the GeoScan device requires reflective Nikkalite reflective labels compatible with HydroCel Geodesic Sensor Nets (GSNs) 130. All new GSNs include Nikkalite labels. The Nikkalite labels are also compatible with the Geodesic Photogrammetry System (GPS), which is an alternative device for 3D electrode sensor registration. For existing customers planning to use the GeoScan device, any sensor nets with legacy labels (black and white) will need to be shipped back to the Magstim EGI Eugene office for relabeling or a new set of sensor nets with Nikkalite electrodes will need to be acquired.
To get started with your GeoScan device, please refer to the GeoScan user manual.
In some cases, the GeoScan device may present some difficulties and scan time may not be as fast as intended. See below some GeoScan use tips and tricks to improve your workflow.
- During the initial scan, the technicians may prefer to hold the unit vertical instead of horizontal. This has been found to be easier on the wrist and does have the advantage of keeping the onscreen image properly aligned.
- Once you have scanned ~95% of the sensors, you can check if you are ready to move on by pausing the scan and reviewing the image on the screen. Double check you have the facial sensors and the alignment sensor scanned. The facial sensors are hard for the software to auto fill and you will not be able to complete the alignment stage if those sensors are not scanned.
- To speed up your scan time, we strongly recommend you disable the stability trigger feature, and use the button to probe and align. With the software running but not during a scan, go to File->Preferences. Uncheck the “Enable Stability Trigger” feature. This feature allows the unit to accept a probe or alignment scan once the probe and net are “visible” by the scanner for two seconds. This will slow the process and also create the annoying “double scan” issue, where the unit accept the same point as the next point to be scanned.
- While probing and aligning, try to position yourself so that you can click the button as soon as you see the red stick on the Mac screen. This usually means on the far side of the subject, in other words, the subject between the Mac and you.
- Use the messages on the screen to re-orient the scanner so both the Net and Probe are visible. The message will indicate whether you need to reorient to “see” more of the net or probe.
- We advise you remove any other infrared sources in the scanning environment. The GeoScan may pick up signals from eye trackers or highly reflective surfaces, for example, which will introduce errors to your 3D electrode sensor net. This also applies to the GeoScan probe, which should be kept with the reflective stickers face down when not in use.
With practice, you should be able to get close to 5 minutes total scan time. Training sessions are recommended in which technicians apply the net on each other and take turns scanning with a stopwatch running. You can make it a contest of it, first person under 5 minutes gets a prize!
If you’d like to set up remote or onsite training for use of the GeoScan system, or if you have any other questions please contact the Support Team.
Additional Info
- Product Type: GeoSource and GPS
- Information Type: Application Advice