[R][M] Near Eye Tracking

A project log for T^2 TyMist [gd0138]

I need some virtual desktop monitors that offer 90PPD at 90Hz.

kelvinakelvinA 02/09/2023 at 12:061 Comment

[09:30] Okay. I've been wondering about this for a while but I think it's finally time to start looking into what options or components I need for eye tracking. I feel that, even if I don't obtain a full TyMist solution, eye tracking would speed up / streamline my PC work, just like #Tetent [gd0090]

The best solution would be one that I can use to detect the assumed focal point of the user. The closer something is, the smaller the angle is (if 90 degrees is the eye looking straight ahead). I doubt I'd get that accuracy, but I also don't think I need it as long as the screen focus is user adjustable.

Lets see if I can not invent here. For starters, I know of the Tobi 5 eye tracker which is a Wii-looking bar that's too large for this application (as well as seemingly incompatible with my portable monitor #Teti [gd0022]  setup). I also know prices for these kinds of things are usually >£200 and have mentally set pricing expectations accordingly.

So the first option was looking promising when I was looking in the docs, until I found the price of the device:

"It's… 3.4 grand? Grand? Three thou four? Not 344? 344 zero?"
Then I looked into the DIY version and the cameras are 120Hz. Considering even basic mice have a 125Hz polling rate and eyes move so much faster, I'm not impressed. The DIY edition also has a non-commercial licence, which sounds iffy. 

There weren't any hardware solutions after the first one, so I'll have to invent here. I just watched a video of what happened when Target tried to outsource a software solution (and now they do 70% inhouse, according to a comment) so inventing here might not be so bad.

It seems that the main thing I need is an infrared camera. Well most cameras can detect infrared (and thus actually require a filter for them), so I have the 330fps camera I planned to use for the #SecSavr Sublime [gd0036] in the back of my mind, but I first wanted to see if I could use a mouse sensor camera. I hopefully don't need a great deal of resolution for tracking the eye, and those sensors are much faster and cheaper. They're also small so, along with the low price, I could have more than 1 sensor per eye for increased accuracy / reliability. 

So I the watched the above video. It seems that the sensors are 40x40px and those high mouse DPIs are a result of interpolation. Is that enough to detect an eye? Could I even get the raw data off fast enough?

Well there's this paper about using optical mouse sensors for eye tracking so there's probably some promise in there.


Very interesting how all these cool things are only showing up very recently. This is the kind of camera setup I hoped for when I was looking for SecSavr Slime cameras. The only kind at the time was the sensor mounted onto some large 38x38mm module when ribbon-cabled versions of this sensor also existed on Aliexpress (with no board to use them with). 

WOAH! It does 1080p 120fps?! That's a new one! The version I had originally found prior only did 60fps at that resolution. Anyway, for this application I'm only interested in the 330fps options. 

I also got an idea to create a custom lens that cuts the image sensing area in half so that something like dual 320x320px images of the eye can be captured with a single sensor. That sounds like a solid plan; better than wasting free data by capturing the surrounding skin or something. Wait... couldn't I use dual images for triangulation? 😏

The original plan was to have the sensor and illumination take the same path as the displays, but I don't think there would be space in the focal plane for that (oh and I'd lose about 50% of the light just to illuminate and another 50% on the capture, due to the losses from the lenses and beamsplitter) so I thought I'd made the optics holder more useful by integrating the eye tracker gear in there.

I can worry about converting the data into eye position at a later time. Right now, I just need to avoid Garbage In Garbage Out.

[12:50] Here are more up-to-date renders, including the lenses and the 20mm diameter beams that hold them and house the eye trackers:

Potentially useful research links


kelvinA wrote 02/14/2023 at 10:05 point

I've looked around and could only find a >£150 camera that could do >330fps. I think I can be confident that the camera I've found is a good balance of speed, size and cost.

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