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mrk88

calculate gaze displacement between two point

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I would like to measure the displacement of eye movements between two eye samples.

I was using GazeDirection vector for that. However, since these values are normalized between [-1,1], the values and the plot I am getting is wrong.

Can you please guide me about how these values have been normalized? and how to calculate the value of the displacement between two consecutive eye samples.

@Corvus @Daniel_Y

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1 hour ago, Corvus said:

@mrk88 Can you elaborate on what values you're getting that are wrong?

 

From physics, I am using this formula to calculate the distance between two gaze position vectors:

Mathf.Sqrt(Mathf.Pow((curPos.x - previous.x), 2) + Mathf.Pow((curPos.y - previous.y), 2) + Mathf.Pow((curPos.z - previous.z), 2));

But this is not correct for displacement. Because the vectors are normalized and the distance between the two vectors is not actual values and not to the right scale (much smaller).

I expect to have a figure like the one below, for hundreds of eye samples .. (the top figure)

https://www.researchgate.net/publication/235788020/figure/fig5/AS:667218010456066@1536088578181/Example-of-eye-movement-data-Vertical-eye-position-upper-panel-and-eye-velocity-lower.ppm

But. the plot I am getting looks like the attached figure. The vertical axis values should change with the respect to eye fixations and saccades. And when for example I fixate on a point for a several seconds it should remain constant over there (not quickly drop to zero).

fig1.png

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@mrk88 For the top figure you refer to, it appears to be measuring the position over time, not the displacement.

From the published article: "Vertical eye position (upper panel) ... as a function of time since fixation onset at 0 ms."
 

 

image.thumb.png.2c75c398b02c587db336aa9e64412650.png

 

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