Eye tracking: Difference between revisions
Jump to navigation
Jump to search
(Created page with "<!-- The experimental sort of eye tracking usually * illuminates the inside of the eye with near-infrared * -->") |
mNo edit summary |
||
| (4 intermediate revisions by the same user not shown) | |||
| Line 3: | Line 3: | ||
The experimental sort of eye tracking usually | The experimental sort of eye tracking usually | ||
* illuminates the inside of the eye with near-infrared | * illuminates the inside of the eye with near-infrared | ||
* | * IR camera that is zoomed in to look at just the eyes | ||
'''You need a comparison.''' | |||
Hold your head still and look around. | |||
Your pupils are now a good indicator of proportional movement. | |||
(You still want to calibrate what the extents are, but that is something you needed ''anyway'') | |||
Now rotate your head and keep looking at the same spot. | |||
Your pupils are moving from left to right within your eye sockets -- yet the place it should detect does not move at all. | |||
From ''just'' the image of the pupil in the eye, you would not get a halfway decent direction. | |||
We can fix that by fixing your head in place, and while "please rest your chin here" is fine, | |||
"please allow us to clamp your head in place"... makes people not like you much. | |||
Another fix to this is to also track the cornea. | |||
Corneal-reflection-style eye tracking (there are others) adds a reference. | |||
That reference is the back of the eye. It is also free to move but, being (roughly) spherical, | |||
whatever the backmost part of the eye is (which is the part that will reflect), | |||
the place of most reflection will barely move when the eye looks around, | |||
so it acts as an anchor. | |||
This definitely still has limitations, but is also a good step less janky than just pupil. | |||
"Can't you add, I dunno, 3D head tracking?" | |||
Yes, and that can help, but at the same time also adds assumptions to the whole, as well as another limited-accuracy thing . | |||
"Can you do this with a webcam?" | |||
At all? Yes. | |||
Accurately? No. | |||
You can download an app for your phone right now. And its output will be... not great. | |||
Why? Multiple reasons | |||
'''"Could I do this with an IR-sensitive webcam?"''' | |||
...plus an IR illuminator? | |||
It would work better than just a webcam, but still not great. | |||
'''Just plain resolution''' | |||
Also, most webcams are wide angle. That leaves a dozen pixels for the pupil. | |||
You can imagine that tracking across thousands of pixels on a screen, | |||
using a few dozen pixels of observable movement, is not going to go well. | |||
Higher res doesn't help a lot due to the optics and typical lighting | |||
and the way various webcams sort of invent a few pixels. | |||
You need either something close to your eyes, or zoomed in. | |||
https://www.tobiipro.com/learn-and-support/learn/eye-tracking-essentials/how-do-tobii-eye-trackers-work/ | |||
https://imotions.com/blog/eye-tracking-work/ | |||
https://xd.adobe.com/ideas/process/user-research/eye-tracking-and-usability/ | |||
https://eyeware.tech/blog/what-is-eye-tracking/ | |||
--> | --> | ||