[open] Re-calibrate Eye Tribe

harold_mb

Hi,

I am running an experiment using the Eye-Tribe.

As the eye-tracker is portable and new, and as my experiment is quite long (72 trials), I want to insert a few breaks and re-calibrate the tracker. I am now drift-correcting before every trial, but I would like to repeat a full calibration.

I created a conditional break half-way through and inserted another Pygaze_init. I get the error message
"You should have only one instance of pygaze_init in your experiment"

I can understand that Pygaze_init is not only calibrating, but also initializing the tracker, so it shouldn't appear twice. But I need to insert a new calibration.

How can I get this done?
Unfortunately, I am not a programmer and I am using OpenSesame from the GUI interface.

Any help would be hugely appreciated
Thanks

h.

sebastiaan

Hi Harold,

You can simply insert an inline_script with:

eyetracker.calibrate()

As described here:

• http://osdoc.cogsci.nl/devices/pygaze/#function-overview

(In 2.9 or earlier, you need to call exp.pygaze_eyetracker.calibrate().)

Cheers,
Sebastiaan

harold_mb

Thank you Sebastiaan!!

*** edit (I always think there is more into coding than there really is)

it works fabulously, thanks.

h.

harold_mb

harold_mb

Unfortunately, it seems I still have a problem.
I introduced two breaks and two re-calibration in my script.
The second re-calibration makes the experiment end prematurely.
I do not get an error message, but the message 'the experiment is finished'. One third of the trials, though, did not run.

Any suggestions?

Thank you

harold

harold_mb

I created a different pilot experiment to see what the problem could be with the recalibration killing it.
This simpler one runs ok 2/3 of the times, but occasionally gives me a Runtime Error:

Microsoft Visual C++ Runtime Library
Program... opensesame.exe
This application has requested the Runtime to terminate it in an unusual way.

I have seen some other users are having problems with Runtime errors
http://www.cogsci.nl/forum/index.php?p=/discussion/1675/open-runtime-error-while-adjusting-script-of-form-plug-in#Item_8
but that description doesn't apply to my case.

Thank you

harold_mb

I took a look at the debug window, and I found a message after the premature end:

*Exception AttributeError: " ' LaminaPanelSurface' object has no attribute '_txtr' in bound method _LaminaPanelSurface.__del__of
expyriment.stimuli._visual._LaminaPanelSurface object at 0x158C3C70 ignored*

I don't know if this is relevant to my problem.

sebastiaan

Hi Harold,

It seems like something goes wrong in Expyriment, the library used by OpenSesame. I cannot really say much more about it, because I've never seen this issue myself, and these kind of 'hard' crashes are very difficult to debug.

But, since the problem seems to be in the xpyriment backend, you could simply try a different backend. You can change this in the General properties tab. For example, does everything work smoothly if you use the legacy backend?

Cheers,
Sebastiaan

harold_mb

Hi Sebastiaan,
Thank you for your answer.

I worked on the script to identify the problem, and I finally fixed it.
In my experimental sequence, I had various elements (a sentences, some pictures, and a question) and then a logger. When I added a break sketchpad and the recalibration, I had put it between these elements and the logger. By changing the place of the logger and putting it closer to those elements, everything now works fine. It seems that these elements were intervening between the response and the logger and were creating a conflict.

Thank you for your assistance and for the development of these open source tools.

best
h

harold_mb

Hi

I am still having some crashes if I restart the calibration. I updated to version 3. It does not all the times, but it can happen in the initialization as well as in my in-line script.
The debug window reports the error as "calibration is already in progress", identifies it in calibration.start() and it tags it as error 403.

Is there anything I could do about it?
Thank you

h

sebastiaan

Hi,

Could you post the full stacktrace? You can find that in the debug window.

And is there any regularity behind the crash. For example, can you take certain steps to reliably reproduce it?

Cheers,
Sebastiaan

harold_mb

Hi Sebastiaan,

here's the problem:

Recalibrating sometimes leads to a crash. I updated Opensesame to version 3 and I am using Legacy. I introduced an inline script for recalibrating every 1/3 of trials, using the function eyetracker.calibrate()

If calibration is unsuccessful and I press R to restart, it crashes and I get this message (while I don’t seem to have this problem if I restart a successful calibration)

*Error while executing inline script

item-stack: experiment[run].experiment_loop[run].recalibration_inline_script[run]
exception type: Exception
exception message: Error in calibration.start: Calibration already in progress (code 403)
item: recalibration_inline_script
time: Tue Nov 10 13:51:18 2015
phase: run

Traceback:
  File "dist\libopensesame\inline_script.py", line 96, in run
  File "dist\libopensesame\python_workspace.py", line 160, in _exec
  File "<string>", line 2, in <module>
  File "dist\pygaze\_eyetracker\libeyetribe.py", line 193, in calibrate
  File "dist\pygaze\_eyetracker\pytribe.py", line 1127, in start
Exception: Error in calibration.start: Calibration already in progress (code 403)*

Thanks for any suggestion
h

alisdt

It's not ideal, but for now this can be fixed with a monkeypatch to the pytribe.calibration class. This simply aborts any current calibration and retries, if necessary.

import pygaze._eyetracker.pytribe

def start_new(self, pointcount=9):

    """Starts the calibration, using the passed number of calibration
    points

    keyword arguments

    pointcount  --  integer value indicating the amount of
                    calibration points that should be used, which
                    should be at least 7 (default = 9)
    """

    attempts = 0
    max_attempts = 3
    while attempts < max_attempts:
        # send the request
        response = self.connection.request('calibration', 'start', {'pointcount':pointcount})
        # return value or error
        if response['statuscode'] == 200:
            return True
        self.abort()
        attempts += 1

    raise Exception("Error in calibration.start: %s (code %d)" % (response['values']['statusmessage'],response['statuscode']))

pygaze._eyetracker.pytribe.calibration.start = start_new

alisdt

p.s. I should have said, for this fix to work the code above should be in an inline code item right at the start of the experiment (before any use of pygaze_init).

harold_mb

This solution seems to work fine. I'll pilot more and update in case.

Thanks

sebastiaan

@alisdt That's great, thank you. Since you seem to known what you're doing, would you be interested in submitting a pull request with this fix through GitHub? If so, please submit it to the os3 branch of my fork, which currently has the most up-to-date code.

If not, no problem, and I'll push a fix myself.

sebastiaan

Hi @alisdt and @harold_mb,

I added a variation of this fix to PyGaze, which is newly packaged in the 3.0.3 prerelease. Would you mind trying out the latest prerelease (not 3.0.3a3) to see if this resolves the recalibration issue?

• http://files.cogsci.nl/software/opensesame/pre-releases/

Cheers,
Sebastiaan