Tobii Eyetracking & Garmin GPS/ANT+ Data for Sports and Real-World Wayfinding Research October 31, 2016Posted by Scott Hodgins in Biometric, eye tracking, Glasses, Tips And Tricks, Tobii, Uncategorized.
In Jon’s previous blog post he mentioned me running and training with some friends over at Forest Fit Clubs and added a video link. I wanted to reply to the inevitable questions about data overlays etc. and how did we do this with the Tobii software? The short answer is that we didn’t, here’s a “how to” to get you started.
This version is based on a running, other examples include:
- Wayfinding – overlay GPS data on the eyetracking video so you can immediately see where pedestrians moved in the built environment. Understanding how people use signage, do they see it? do they understand and use it?
- Driving & Flying – use the GPS and speed/G-Metrix data to understand the technique and relationships between looking-engaging and acting on that information.
- Data overlay’s are not just limited to the Garmin descriptions – you can hack the overlays to change the title and add maybe GSR data, or cognitive data and arousal metrics from an EEG such as the ABM X-10
We wanted to show the power of adding basic data overlays onto the eyetracking video so we could easily associate an action from the video with a resultant change in data. We had a Garmin VIRB XE that we had used for a technical demonstration with a customer. I had noticed that the VIRB produced MP4 files, as did the Tobii Glasses 2 (TG2), so the idea of hacking the workflow, swapping the VIRB video out and overlaying biometric and location data over the TG2 video data was born. Below is a video showing an overview of the software.
The kit list:
1 x Tobii Glasses 2 (any variant)
1 x Garmin Fenix 2 Sports watch (now replaced by the Fenix 3 and Fenix 3 HR, which may be an alternative source for HRM data)
1 x Garmin HRM RUN Heart rate monitor, we wanted this as it also offered specific run data, not just HR
1 x Garmin VIRB XE & Garmin VIRB Edit Software (we didn’t use the camera, just the software)
1 x Willing participant (me, and yes I calibrated myself, in daylight, outside, it is super-easy with the TG2) with a suitable pocket or running belt to stash the recording unit in.
- Assemble the TG2:
Connect Head Unit-Cable-Recording Unit, Insert SD Card, Insert Battery & power up. This took about 5 minutes instead of the normal 2 minutes as I threaded the cable under my base layer to control the cable movement and placed the recording unit in a neoprene running belt to control movement. (1)
- Power up the controlling computer, we use Dell Venue 11 Pro’s (Now Dell Latitude 11 5000) running W7 Pro or W10 Pro x64.
- Connect to the TG2 WLAN, start Tobii Glasses Controller, select “New Recording”, add a participant name and description.
- Calibrate: Select the icon in the bottom right of the screen to calibrate (easy on the tablet – just touch) and look at the calibration marker – for non Tobii users a fully 3D calibration is completed typically <5s. A major advantage of this ground-breaking 3D calibration model is that we don’t have to try and “work around the data” during analysis. (2)
- Start the recording, then start the recording on the Garmin Fenix while looking at the screen – it’s not perfect but we should be able to sync the data to the frame where the recording started and at 25fps video we are sure that we are sync’d to about 40ms. (3) Turn the laptop off, or put it in sleep mode.
- Run around, enjoy the beautiful scenery at Somerley.
- Finish session, cool down, stretch – up to 90 minutes per battery so we have plenty of time head back to the car and stop the recording on both the Garmin Fenix and the TG2
- Stopping the recording, then select the recording and start to output the 1080p HD video.
- Sync Garmin to the cloud – in this case it was Bluetooth to Garmin Connect on my iPhone then auto sync’d to the cloud (connect.garmin.com)
- Login to your connect account, select the activity and download the FIT or GPX data from this session.
- Open VIRB Edit, create a new video and import the video you exported from the Tobii Glasses Controller, then add this to the video timeline.
- Import the FIT or GPX data, click on G-Metrix and then on Data and find your file.
- Sync the two files using one of the options at the foot of the G-Metrix>Data dialogue.
- Now use either the Templates and Gauges options to add data overlays on to the video, you can use appearance to change the colour of the gauges.
- Importing the logo & setting up a new template is more art than science – good luck with that, I think it took me about a dozen failed attempts then it magically worked, I took the time to try again while writing this, it now shows as a Beta function in the software.
- Export the video to your chosen resolution and quality.
The next post will look at doing something similar, using TEA Captiv as a more scientific option, with multiple video feeds and more data options.
The end result:
- It is worth taking 5 minutes here to make sure you have free movement before starting, otherwise turning too sharply could lead to disconnection or discomfort. Because I used the wireless version, once I was wired up and adjusted I didn’t need to touch the system again until I was retrieving data.
- Other wearable/head mounted eyetrackers have issues when we start looking in different planes. Their calibration model is typically a one dimension transform that is adequate when looking in the calibrated plane, the calibration will suffer when looking in a different plane. For example if we calibrate on a vertical wall (looking at the corners of a picture) then place that picture flat on the desktop we will see trapezoidal offsets, this is also true if we calibrate in a horizontal plane (desk) and look at a vertical target (wall). The result is that if we are not cognoscente of this and take the distorted (erroneous) data at face value we risk producing worthless results.
- There is a sync port on the Tobii that can send/receive an LVTTL pulse to/from an external device, however the Garmin watch isn’t designed for this so we chose to keep it simple with a video based sync.
- Garmin data formats, I have always used the GPX download to import into VIRB Edit, the FIT data caused a few anomalies specifically with time and GPS origin. The FIT file has all of the data recorded in Garmin Connect, the GPX has less, there was still enough for this example though.