WorldViz User Forum  

Go Back   WorldViz User Forum > Vizard

Thread Tools Rate Thread Display Modes
Old 05-22-2016, 04:40 PM
performlabrit performlabrit is offline
Join Date: Oct 2013
Posts: 77
Post-hoc fixation detection from a noisy eye-tracker signal.

I'm looking for tips! I'm using an eye tracker, and brainstorming an algorithm for detecting if someone is fixating upon a target object. The most straight forward approach would be to cast a "gaze vector" from the camera center into the virtual world, and testing for an intersection of this vector with a target object. The issue is that the "gaze vector" may waver on/off the object between frames, or even be slightly and stably off the object by a few degrees.

Note that this data is going to be collected and analyzed OFF-LINE - so that I can filter the gaze signal and apply some corrections.

The ideal solution would take into account the view-dependent outline of the object projected upon the view plane, rather than relying upon a bounding box / circle. So, it makes sense that one would want to solve this problem after having already performed the perspective projection onto a viewing plane.

So, the solution I'm contemplating is this: for potential fixation targets, create a double. Place it at the same place, in the same orientation, but set alpha to 0 and scale up the size.

Fixations upon the target would be calculated by intersecting the gaze vector with the invisible target object.

Any thoughts / tips?

- gD
Reply With Quote
Old 05-23-2016, 08:13 AM
performlabrit performlabrit is offline
Join Date: Oct 2013
Posts: 77
...another point.

...I should say that the scaling of the invisible target would reflect the threshold for fixation in angular degrees.

The downside to this is that one must set the threshold BEFORE running the simulation. In my experience, thresholds must often be specialized to the individual, and to the characteristics of post-calibration track quality.

I'm happy to chat with any Worldviz guys about this kind of thing! I hope that you guys are considering building this kind of functionality into Vizard itself. Not that many folks seem to be thinking about this yet, but the demand is surely going to increase over the next few years.
Reply With Quote
Old 05-24-2016, 04:15 AM
Jeff Jeff is offline
WorldViz Team Member
Join Date: Aug 2008
Posts: 2,471
I'll check with our developers for suggestions here.
Reply With Quote
Old 11-15-2017, 02:58 AM
Catota Catota is offline
Join Date: Nov 2017
Posts: 1
Any news here?
Reply With Quote

eye tracker, eye tracking, fixation detection

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Intermittent orthographic stereo projection problems AySz88 Vizard 10 02-17-2012 12:50 PM

All times are GMT -7. The time now is 11:43 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright 2002-2023 WorldViz LLC