The Eye Tribe

Hi developers!
I have question-pupil diameter varies depending on the distance from the eye tracker, such as at 70 cm - 25 pixel, 60 cm - 20 pixel/ and so on/, or the size of the diameter of the invariant? how many "angular size" of the pupil at a distance of 70 cm?

For me does't make sense the pupil size to be in pixels, because it is a float point value...My guess: it is mm

May be the Eye positon (raw and smooth) are in virtual pixels.

Well, but I have no idea!

- - - - - - - -

I would like add few more questions


From: http://dev.theeyetribe.com/api/#cat_tracker

Whats the difference beteween Eye coordinates ans pupil coordinates? How to get one from the other?

Are pupil coordinates raw or smoothed?

What's pupil size? diameter? Is it mm?

Regards,
Edgard

Currently pupil diameter is raw sensor units (pixels) and not converted to millimeters, that is why the value change depending on distance to the sensor. It is a float because the measurement is computed with sub-pixel precision. There might be changes to pupil diameter measurements in coming software updates (frequent request).

Pupil center position is normalized (virtual if you will) into a range of 0-1 for ease-of-use. If absolute values were used one would have to compute against sensor resolution to get the actual position, and the resolution is typically specific to a certain device-model. These values are not smoothed.

Eye coordinates is the on-screen gaze position for the screen used to calibrate (both raw and smoothed). Top left is 0,0 and bottom right is max screen width/height (for example 1920, 1080).