[atamasan]

Hi, thank you for your advice.

Yes, the cube I made and the real transmitter are in the same coordinate system.
Oh I didn't have ideas about offset.
The size of the real transmitter is 10*10*10[centimeters]. So I defined the cube like this. cube=viz.add('box.wrl') cube.setScale([.1,.1,.1]) In this case, the size of my cube is 10*10*10[centimeters]??

By the way, a polhemus sensor is linked to my HMD, but it's not placed at display monitor of the HMD. It's placed at my forehead now. And then, datas from the sensor is linked to "viz.MainView".
I noticed that the sensor is oblique angle against the HMD, so I think this could cause problems. Because when I look at the front, "viz.MainView" don't look at the front.

Anyway I'll try your advices. Thank you very much.