Arrington Plugin

[Uttama_vizard]

Hello,

I am trying to interface an Arrington Eye Tracker with the Vizard platform. When I am trying to access the tracker data by using

import vpx
point = vpx.getSmoothedGazePoint()

I am getting this error

import vpx
ImportError: DLL load failed: The specified module could not be found.

I have seen that my vizard\bin file has the vpx.dll.

If anyone can suggest me something, it would be really helpful to me.

Thanks

Uttama

[Uttama_vizard]

Hello,

Another thing I forgot to mention. Presently I am running both the applications on the same PC.

Thanks

Uttama

[farshizzo]

Which version of the Arrington Eye ViewPoint software are you running? Also, is the ViewPoint folder on your system path. The vpx plug-in depends on some DLLs that are in the ViewPoint folder. So either that folder must be on the system path, or your script has to be run from inside that folder.

[Uttama_vizard]

Hello Farshizzo,

The Viewpoint version I am running is ViewPoint(2.8.4 beta L4 437B). The Viewpoint.exe is in the Viewpoint Folder. It is running fine.

The vpx.dll folder which I have downloaded from the Worldviz Downloads section is in Vizard\bin\dll folder.

I have also tried loading the vpx.dll in the ViewPoint folder. It did not work.
Again, I loaded the vpx.dll in the folder where I my vizard program .py is. Still it gives the same error.

Thanks in advance for your time. I am not being able to solve this...your suggestions would be really valuable.

Thanks

Uttama

[Uttama_vizard]

Hello Farshizzo,

Your suggestions are always great!! Yes, now I have copied my .py file and the vpx.dll into the ViewPoint folder and now the error does not appear again.

But, it seems, I am getting the x and y coordinates and that too of one eye. I want to access those for the other eye (as I am using a binocular system) and also the ROI and other parameters.

point = vpx.getSmoothedGazePoint()

gives x,y coordinates and that too for one eye.

If you can suggest me some ways to access the other data as well.

Thanks

Uttama

[Uttama_vizard]

Hello,

I am finding no commands explicitly mentioned for Arrington Tracker in the Help menu.

From the downloads page, I got only,

import vpx
point = vpx.getSmoothedGazePoint()

The Help file alongwith Vizard package also does not show these.

Thanks

Uttama

[farshizzo]

The vpx plugin only supports getting the gaze point of one eye. You could use the ctypes module to manually access the function of the Arrington Viewpoint API. What specific functions do you need, other than getting the gaze point of both eyes?

[Uttama_vizard]

Hello,

At present, I want to access the Pupil Width (APW and BPW), Quality of eye movement data (AQU and BQU), Fixation Duration (AFX and BFX) and the x,y gaze direction coordinates (ALX, ALY and BLX, BLY) for both the eyes.

Thanks for your patient help.

Uttama

[Uttama_vizard]

Hello,

Actually, I would be carrying out some psychological experiments using the Arrington eye tracker. So, Pupil Width (APW and BPW), Quality of eye movement data (AQU and BQU)-if possible, Fixation Duration (AFX and BFX) and the x,y gaze direction coordinates (ALX, ALY and BLX, BLY) for both the eyes would be required.

I was looking for the ctypes in the Vizard help menu. I could not find sustantial amount of information regarding ctypes. So, any help in using ctypes would be really appreciated.

Thanks in advance for valuable suggestions.

Uttama

[farshizzo]

ctypes is 3rd party plugin for Python. You can find a tutorial for the plugin here:
http://python.net/crew/theller/ctypes/tutorial.html

[Uttama_vizard]

Hello,

Thanks for the suggestion. I have downloaded the ctypes.

When, I am writing:

from ctypes import *

There occurs no error.

The tutorial says....

libc = cdll.msvcrt
libc.printf

I am getting <_FuncPtr object at 0x00B80B70>

So, in my case....do I use.....?

vpx = ......msvcrt
vpx.printf

Any suggestions.....actually, I want to access vpx.dll and insert the other features such as coordinates of both the eye gazes...I hope my question is clear...

In fact, I am little confused regarding the approach to be used.....and not sure whether I am going the correct way.

Any suggestions would be really appreciated.

Thanks for giving your valuable time.

[Uttama_vizard]

Hello,

Any further suggestion regarding ctypes would be really appreciated. I have given my problem...in the last posting.

If required, I will clarify further.

Thanks

Uttama

[farshizzo]

I'm not very familiar with ctypes, so I cannot help you that much. I think the important thing is that you are using the correct function name. In your example, you are using printf, which is not a function exported by the vpx.dll

[Uttama_vizard]

Hello,

Sorry for the delay in replying.

How do I know which are allowed and which are not allowed in vpx.dl? Like...printf is not allowed in vpx.dll.

It would be really good, if I have the .cpp or .c file corresponding to the vpx.dll, so that I can put some thinking how to modify it so as to incorporate the tracking of the other eye?

Thanks

Uttama

[farshizzo]

You will need to obtain the vpx API from Arrington, which will contain a header file defining all the functions exported by the dll.

[kpraveen]

I am trying to interface the Arrington eye tracker with the vizard platform and try to get the gaze point values in real time.
When i run the program there is no error but it does not show the gaze point in real time too.Hereby,i will send you my program and the following command i am getting.

Program:

from ctypes import *
import viz
import os
import sys
import vpx
viz.go()
point=vpx.getSmoothedGazePoint()
print 'point'
print point

Command:

********************************
** Loading arrington.py
**********************************
point
(0.0, 0.0)
** Load Time: 0.22 seconds

kindly,help me out to get the data's in real time and for your information i have downloaded vpx.dll from the hardware support section of worldviz and saved it in the working vizard directory and all the files are saved in ViewPoint 2.9.2.5 directory and i am using windows xp 32-bit system.

if anyone can suggest me the way of getting the data's in real time and it is really helpful for me.

[Jeff]

Use the arrington plug-in to get gaze point data.

import viz
import vizact
viz.go()

#Create arrington extension 
arrington = viz.add('arrington.dle')

#Connect to eye tracker
tracker = arrington.addEyeTracker()

def printData():
	#Print smoothed gaze position (default)
	print tracker.getPosition()
	#Print raw gaze position
	print tracker.getPosition(arrington.RAW)

vizact.onupdate(0,printData)

[kpraveen]

Thank you for your reply Jeff,

I executed the code which is in Arrington plug-in and also send by you and getting the following command...

[0.0, 1.0, 0.0]
[0.0, 1.0, 0.0]
[0.0, 1.0, 0.0]
[0.0, 1.0, 0.0]
[0.0, 1.0, 0.0]
[0.0, 1.0, 0.0].........it is continuously going on and unable to get the real time value of Gaze point.

so,give me suggestions to get the value in real time.Thank you for spending time to solve my issue.