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  #1  
Old 01-25-2017, 01:04 PM
Canucks Canucks is offline
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Treadmill , Optotrak & Vizard

We are trying to run Vizard for Optotrak in which the participant walk on the treadmill. The problem is since it's on a treadmill, on Vizard it shows it as going back & forth ( not moving forward) since the coordinates are not changing ( ir: you go from (0,0,1) to (0,0,2) even if you go 10K on treadmill). Is there way to fix this issue?
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  #2  
Old 01-25-2017, 04:18 PM
Jeff Jeff is offline
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Use vizconnect to configure the viewpoint to move with optotrack data. Add a group tracker above the headtracker in the vizconnect scenegraph and update the group's position in the script that imports the vizconnect config file based on the treadmill speed. Take a look at all the vizconnect tutorials to get started if you're not familiar with vizconnect.
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  #3  
Old 02-01-2017, 04:10 PM
Canucks Canucks is offline
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Thank you for your reply. I created group tracker in the vizconnect. I'm wondering how can we read treadmill speed to update my mainview position? Are you suggesting let's say treadmill speed is 2 MPH, should I update the position based on that?
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  #4  
Old 02-01-2017, 07:16 PM
Jeff Jeff is offline
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I'm not sure how you would get the treadmill data in Vizard. Does the manufacturer provide a Python API? If so, you could use that to get the data into Vizard. Attached is an example that updates a group tracker every frame to move the viewpoint.
Attached Files
File Type: zip groupTrackerExample.zip (3.9 KB, 181 views)

Last edited by Jeff; 02-02-2017 at 10:27 AM.
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  #5  
Old 04-28-2017, 02:07 PM
Canucks Canucks is offline
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Hi Jeff,
what is unit for scale in vizard? m/s?
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  #6  
Old 04-29-2017, 01:14 AM
Jeff Jeff is offline
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Can you describe further the code you are referring to that's scaling the movement?
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  #7  
Old 04-29-2017, 07:18 PM
Canucks Canucks is offline
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You sent me the simulated treadmill .. i'm wondering what's the unit of speed is so I can adjust with ours
TREADMILL_SPEED = .05

viz.add('sky_day.osgb')

# Add ground model 20 times
for i in range (20):
viz.addChild('ground_grass.osgb', cache = viz.CACHE_CLONE, pos = [0,0.01,i+25])

groupTracker = vizconnect.getTracker('treadmill_node').getRaw()

def updateGroup():
groupTracker.setPosition([0,0,TREADMILL_SPEED],viz.REL_LOCAL)

vizact.onupdate(0,updateGroup)
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  #8  
Old 05-01-2017, 10:41 PM
Jeff Jeff is offline
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The following code allows you to specify the speed in meters per second:

Code:
# Speed in meters per second
SPEED = 1

def updateGroup():
	# Get the elapsed time since the previous frame and multiply that against the speed in m/s
	groupTracker.setPosition([0,0,SPEED * viz.getFrameElapsed()],viz.REL_LOCAL)

vizact.onupdate(0,updateGroup)
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coordinate system, optotrak, treadmill, vizard

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