You can use the
<node3D>.setPosition command to set the ball at ground level:
Code:
import viz
import vizact
viz.go()
ground = viz.addChild('tut_ground.wrl')
ball = viz.addChild('ball.wrl')
ball.setPosition([-2,0.5,7])
move = vizact.moveTo([2,0.5,7],speed=1)
vizact.onkeydown('1', ball.addAction, move)