#1
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tracking with multiple LEDS
Hello.
I've been trying to solve the age-old problem of tracking multiple LED lights, and linking one of them to the head, despite the fact that there's no inherent identity to the different lights. We had the system installed just a while ago, and with Paul ( from worldviz ) we tried to work out something which would handle head+hand tracking. attached is the code - it works on a tryouy with markers and keyboard/mouse tracking, but get's messed up when i try it with PPT tracking, and things don't get tracked correctly. ( both ppt's end up moving the head, and none the hand, and strange leaps occur ) ######################### ### ##HERE IS THE CODE####### ######################### import viz import __main__ import viztracker head = viz.addGroup() hand = viz.addGroup() pos1 = None pos2 = None headLink = None handLink = None head_ori = None hand_ori = None posHeadLink = None posHandLink = None STEP_SIZE = 4 # STEP_SIZE * real step in life = the step in the VR def setUp(): global head,pos1,pos2, posHeadLink, posHandLink, head_ori,hand_ori __main__.PORT_PPT = 1 pos1 = viz.add('vizppt.dls') pos2 = viz.add('vizppt.dls') __main__.PORT_INTERSENSE = 4 hand_ori = viz.add('intersense.dls') __main__.PORT_INTERSENSE = 5 head_ori = viz.add('intersense.dls') # pos1 = viztracker.Keyboard6DOF() # pos2 = viztracker.MouseTracker() # head_ori = viztracker.Keyboard6DOF() # hand_ori = viztracker.Keyboard6DOF() posHeadLink = viz.link(pos1,head,enabled=False,mask=viz.LINK_POS ) oriHeadLink = viz.link(head_ori,head,enabled=False,mask=viz.LINK _ORI) posHandLink = viz.link(pos2,hand,enabled=False,mask=viz.LINK_POS ) oriHandLink = viz.link(hand_ori,hand,enabled=False,mask=viz.LINK _ORI) vizact.onupdate(viz.PRIORITY_PLUGINS+1,posHeadLink .update) #Manually update link after plugins vizact.onupdate(viz.PRIORITY_PLUGINS+1,oriHeadLink .update) #Manually update link after plugins vizact.onupdate(viz.PRIORITY_PLUGINS+1,posHandLink .update) #Manually update link after plugins vizact.onupdate(viz.PRIORITY_PLUGINS+1,oriHandLink .update) #Manually update link after plugins update() def getHead(): return head def getHand(): return hand def update(): y1 = pos1.getPosition()[1] y2 = pos2.getPosition()[1] if y2>y1 : posHandLink.setSrc(pos1) posHeadLink.setSrc(pos2) else : posHandLink.setSrc(pos2) posHeadLink.setSrc(pos1) #scaleLink = posHeadLink.postScale([STEP_SIZE,1,STEP_SIZE],target=viz.LINK_POS_OP) #Scale movement factor def resetPos(): posHeadLink.reset(viz.RESET_X | viz.RESET_Z) posHandLink.reset(viz.RESET_X | viz.RESET_Z) def resetOri(): head_ori.reset() hand_ori.reset() vizact.onkeydown(' ',update) vizact.onkeydown('t',resetPos) vizact.onkeydown('r',resetOri) if __name__ == '__main__' : viz.go() #myroom = viz.add('C:/Dan/WorldViz/Vizard30/tutorials/gettingstarted/room.wrl') setUp() marker1 = viz.add('marker.wrl') marker2 = viz.add('marker.wrl') viz.eyeheight(0) marker1.color([1,1,0]) viz.link(head,marker1) viz.link(hand,marker2) #viz.link(head,viz.MainView) ####################### END OF CODE ####################### I also looked at the forum post from 2003 http://www.worldviz.com/forum/showthread.php?t=175 which talks about the problem there, but i saw the solution given there by the admin doesn't use updated viz terms, such as links and such, ( for example it uses the viz.tracker() command, which i see isn't being used in the viztracker file, so i guessed it was outdated...) but manually translates objects according to position. (Is the solution offered there still possible? would you advise it? ) Hope i was clear enough.... would be happy for any help i could get, i'm pretty desperate myself. I actually want specifically to solve the problem for 3 ppts and 2 orientation sensors ( Head, Hand, and one more PPT on the leg ), so if you could provide me a solution to that problem speficially that would be the best... thanks alot! dan |
#2
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What are the specific constraints for your setup? Is the head always going to be above the hands? Will the user always be facing a specific direction? There is no general solution, so we need to know your exact requirements before we can provide a useful solution.
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#3
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Hi
my requirements -
at the beginning the head will be above the hand, but later on the person being tracked is supposed to lift his hands above his heads, so not always - the same regarding the PPT we want to have on the person's leg - at the beginning we planned to reset the positions, by assuming that head > hand > leg height wise, but later on theoretically the person might lower his hand beneath the ppt on the leg. and the viewpoint should stay linked to the person's head... so in conclusion there won't be any thing permanent throughout the experiment, but we planned to perform an inital reset at the beginning, and later on if for some reason something gets messed up, then to have a keyboard callback which lets us press a key, and perform the same height test, assuming head > arm > leg. Thanks, dan |
#4
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Hey
just to make sure you haven't forgotten about me :\
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#5
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There is no easy solution to this. One method would be to save the initial location of the head/hand/feet when you perform a reset. Afterward, every frame compare the new PPT marker positions to the previous head/hand/feet positions. The marker that is closest to the previous head position will be the head position for the new frame, and so on for the arm/legs. However, this method will break down if you bring the markers close together, or if a marker becomes occluded for an extended amount of time.
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#6
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Why is it not simple to perform the links?
i'm a bit confounded :
The ppt is able to differentiate between different ppt devices , after the initial recognition - this is obvious from the fact that watching the ppt tracking program, each led gets it's own different color, and these colors stay with the correct ppt device ( for the sake of the argument let's assume that the ppt's don't get confused between each other or occluded ). So what prevents us from implementing something which initially finds out which device is the led/hand/head, according to the initial height of the device? Assuming that there is no swapping or occlusion, am i wrong to think that this would work correctly and consistently throughout the tracking session? And since assuming that occlusions and swapppings might occur, that's why we wanted to provide some sort of callback (keyboard), that would perform the height test again, and reorganize the links between the ppts and the different body parts.... i am abit confused about the different link objects in vizard and their functions, and that's why i wasn't really able to implement this myself... ( assuming it's possible ) If this is not possible, i would be happy for an explanation where i'm wrong in my thought process, as i guess i'm missing something..... THANKS! dan |
#7
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If you want to assume that the PPT won't swap markers then what exactly is the problem? Once you determine which marker is connected to the head/hand/legs you can link them to the appropriate Vizard objects (viewpoint,models,etc...) like usual.
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#8
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okay my bad
hey farshi
sadly i admit that there is actually no problem! indeed it seems that it works fine, and the reason it didn't work before, was just because i didn't update the number of trackers being tracked from 1 to 2, and this caused the strange behaviour ( obviously ). well, i'm new to the system! thanks dan |
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