[Solved] Head Pose stream internal error!

[Rishi Kapadia]

A few times, I was able to run the sample interaction 103 app perfectly fine with headtracking data displaying fine. Without modifying anything, somehow the callbacks (event handler) stopped being called. The event handler is being subscribed with += line. Eye gaze and position data continues to work fine however.

To debug this matter, I tried to see if it occurs in C++ using the StreamNative API.

I get TOBII_ERROR_INTERNAL when I run the example code for tobii_head_pose_subscribe():
https://tobii.github.io/stream_engine/#example-26

The description for this error is: Some unexpected internal error occurred. This error should normally not be returned, so if it is, please contact the support

[Rishi Kapadia]

Clarification:
The computer I am talking about above is a Surface Book running Windows 10 Build 14393. It was actually not running “perfectly fine” a few times. When launching sample 103 app, sometimes it would take about 5-10 seconds before any valid head tracking data was shown. Then after about 10 executions, I began seeing error (TOBII_INTERNAL_ERROR code 1). I have tried unplugging and reconnecting the Tobii 4C tracker. I have tried power-cycling my Surface book. Still same error.

I took my 4C and connected it to a Lenovo Thinkpad running a Windows 10 Insider preview build and Tobii’s Core eye tracking hot fix release 2.10.11.6458. Details found here: https://blogs.windows.com/windowsexperience/2017/08/02/announcing-windows-10-insider-preview-build-16257-pc-build-15237-mobile/#45L4HP9Ygw1mZ38l.97

I built the https://tobii.github.io/stream_engine/#example-26 example using VS 2015 as a Win32 Console program, and ran the program on my Lenovo Thinkpad and I am able to see head-tracking data (after about 5 seconds of launching the app). The second time launching the app, I get a code 4 (TOBII_ERROR_NOT_AVAILABLE) – I suspect this is because when I closed the application previously the stream was still open? I run it again, now I see no error and the head-tracking data is displayed on the console immediately.

Head tracking seems a little experimental still. Could someone please provide the algorithms to take the eye positions, and convert it into the head position and rotation data? I’ve not had any problems with the eye gaze, eye positions, or eye fixations and it seems more reliable. Though it doesn’t seem hard, but the fact that Tobii created a separate stream for head-tracking indicates there’s something special that an algorithm which merely uses eye positions would miss out on.

[Grant [Tobii]]

Hi @rishikapadia7, thank you four your detailed report and sorry to hear about your issues.

So it seems that things are working as expected on the Thinkpad but any time you revert the eye tracker back Surface Book, the same issue returns.. and vice versa?

I am afraid that we cannot divulge details regarding the algorithms but it’s certainly a rather unusual issue you have discovered for which this is the first time it has been reported. Perhaps another user viewing this point might have seen it before.

In the meantime, I will pass along your information to the developers to see what advise we can give. May I ask if there was in fact any *environmental* difference between the two laptops? ie different rooms ,lighting conditions, etc.?

[Rishi Kapadia]

Hi Grant, both of the laptops were used in the same room under the same lighting conditions. Like I mentioned it doesn’t actually work completely flawlessly on the Thinkpad (there was a 5 second wait before head position data arrived) after running it. I have not yet witnessed that problem on eye gaze or fixation samples. But other than that it’s been fine on the Thinkpad.

Though yeah it is a bummer that headtracking has stopped working on my Surface Book altogether.

[Grant [Tobii]]

Hi @rishikapadia7, good news! We have correctly reproduced and identified this bug within the Core SDK and will include the fix in the forthcoming release. Please Be Sure to check back on the SDK page regularly to be sure of getting the latest version. 🙂

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