Forum
Register Calendar Latest Topics
 
 
 


Reply
  Author   Comment   Page 2 of 2      Prev   1   2
Jaewon

Administrator
Registered:
Posts: 424
Reply with quote  #26 
I still don't get it. Are those two subjects participating in the experiment together? If so, you can record the eye positions of the second subject via General Input, as you said, and manually calibrate them later. You don't have to calibrate before recording, since the second subject doesn't do trials during the experiment.
0
kms

Junior Member
Registered:
Posts: 27
Reply with quote  #27 
Yes, the two will be participating in the experiment together. How do you suggest I do manual calibration without reassigning Eye x and y? 

Thanks.
0
Jaewon

Administrator
Registered:
Posts: 424
Reply with quote  #28 
You need to know the gaze angle and the voltage reading when the subject is looking at a particular point. Is there any fixation point or an object that the subject likes to watch? What is the subject doing during trials?
0
kms

Junior Member
Registered:
Posts: 27
Reply with quote  #29 
Thanks, Jaewon. The subject is free to look anywhere during the task but I want to make sure that all his saccades to an experimental area of interest [subject 1] are tracked well.

I think I now understand what you mean by manual calibration. I will give this a try though, of course, I will prefer something more automatic like the origin and gain method. 

Thanks.
0
Jaewon

Administrator
Registered:
Posts: 424
Reply with quote  #30 
Eye position data saved in the BHV is calibrated numbers that are represented in degrees, not raw voltages. Since General Input doesn't get that kind of conversion, you have to do things manually.

You can still get the calibration parameters of the second subject easily with the calibration tools in ML. You just need to save it in a different CFG file. Make a copy of the conditions file and rename it with a different name so that your original _cfg.mat file is not overwritten. Then load that conditions file and revise I/O so that the X & Y channels of the second subject (that you previously assigned to General Input) are mapped to Eye X & Y on the menu panel. Then calibrate the eye signals of the second subject from there and save the settings. Now the calibration parameter of the second subject is in the new cfg file.

Then load the original conditions file and do the experiment. The eye signals of the second subject will be in the General input uncalibrated. Then you can read the second cfg file in MATLAB, get the origin and gain and apply them to the General Input signals. The locations of the origin and gain variables in the CFG are:

MLConfig.EyeTransform{2}.origin
MLConfig.EyeTransform{2}.gain

Does it make sense?
0
kms

Junior Member
Registered:
Posts: 27
Reply with quote  #31 
That sounds great; exactly what I was looking for as a work-around for my specific purpose without having to change the original ML code! 

Thanks a lot, Jaewon!
0
Jaewon

Administrator
Registered:
Posts: 424
Reply with quote  #32 
FYI, the origin and gain calibration works like this.

degree = (voltage - origin) * gain
0
castiel

Junior Member
Registered:
Posts: 4
Reply with quote  #33 
Hello, i have some questions about the calibration of monkeylogic, please help me

Thank you very much!!!

and i'm very confused about this:"Eye position data saved in the BHV is calibrated numbers that are represented in degrees, not raw voltages." what does this mean? and i alse see the formula called:
degree = (voltage - origin) * gain

and you said the origin and gain calibration works like this.

So my problem is that: should i use the formula to calculate the "gain" if my degree is 10°?because i can get voltage with the space bar. Or should i just pull the adjustment lever of GainX and GainY to get calculated? and Does the degree mean the angle between the upper circle and the middle circle?


Looking forward for your reply, will be so so greatful for your help.
0
Jaewon

Administrator
Registered:
Posts: 424
Reply with quote  #34 
Hi castiel,

I am sorry, but I don't understand what is the job you want to do, so I will just tell you what you should know.

1. In the main menu, type the diagonal size of the selected monitor and the viewing distance between the monitor and the subject correctly.
ppd.png 

2. Start the origin-gain calibration tool and set the interval between fixation points, as you want. It is 2 deg in the below figure, which means that the yellow squares (fixation points) on the left are 2 degrees apart one another.
3158636.png 

3. Click the fixation point at the center (or click the "Show Center" button). It will display a yellow square at the center of the subject screen and make the subject look at it. If the eye cursor (red dots on the left) does not overlap with the center fixation point at the moment the subject looks at the point, your calibration is off. Then, either by using the "Origin X" and "Origin Y" slider bars or by clicking the "Set Origin (Space)" button, make the eye cursor overlap with the center fixation point when the subject looks at the center.

4. Choose any fixation point other than the center point and click it. Then use only "Gain X" and "Gain Y" and make the eye cursor overlap with the point you just clicked when the subject looks at it.

5. Click the "Save" button.

6. Now the voltage readings will be converted to visual angles and saved in the data file.



0
Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.