The Billboard helper lets you create geometry that is camera-aligned in the VRML97 browser. The objects always align to the viewpoint in the VRML97 browser.
Any geometry linked to the Billboard helper will rotate about the local Z axis of the helper object to face the viewer. Since it rotates about the location of the Billboard, it is best to center the Billboard on the object that you will link to it.
The direction of the negative Y axis of the object, which will be its front, is aligned with the negative Y axis of the helper, and will be the Billboard surface that always faces the viewer. This is the side usually seen from the default camera position.
To create a Billboard helper object: