WorldViz User Forum - help with augmented reality and physics

im trying to make a simple application with physics and augmented reality.

I want just display a logo above the marker and if i roll the marker the logo will fall from the marker.

But the logo collide s little high above the plane and doesn't fall from the plane when i roll the marker.

Code:

import viz



viz.go()

viz.phys.enable()   # Enable physics

viz.phys.setGravity(0,-9.8/6,0) #Half Gravity



#Add ARToolkit extension

ar = viz.add('artoolkit.dle')



#Create camera using first available webcam

camera = ar.addWebCamera()



#Create marker from pattern file

marker = camera.addMatrixMarker(10,width=1000)



#Ground

ground = viz.add('tut_ground.wrl')

ground.setScale(0.03,1,0.03)

ground.alpha(0)

ground.collidePlane() # Collide Plane

logo = viz.add('logo.wrl') # Add logo



viz.link(marker,ground)



logo.setScale(0.5,0.5,0.5)

logo.collideBox(bounce=1)

logo.add('box.wrl',alpha=.2,scale=logo.getBoundingBox(viz.REL_LOCAL).size)



def resetLogo():

        x,y,z = ground.getPosition()

        logo.setPosition([x,y+2,z])



vizact.onkeydown(" ",resetLogo)