TABLE OF CONTENTS Entourage is a term taken from traditional architectural rendering. It refers to photographic "extras" that are added to a rendering to make it appear more realistic. You can think of entourage as cutouts or props that are added to the scene to make it more lifelike. Examples of entourage are people, trees, cars, street furniture, and signs. Entourage is not really 3D models, however. As 2D photographic elements, they are handled mainly through materials.
The key to designing an entourage material is to use an opacity map to hide unwanted portions of the surface to which the texture is mapped. Generally entourage materials are applied to Plane or Box primitives that act like flat billboards, displaying their contents for the world to see. Once you apply an opacity-mapped material to an object, it is also important to adjust the object to fit the bitmap's aspect ratio or undesirable stretching will occur.
An opacity map is a grayscale bitmap image that tells VIZ which part of the surface is opaque and which part is transparent. The black portions of an opacity map become completely transparent, whereas white is completely opaque. Shades of gray create varying degrees of opacity.
To see how this works, look at Figure 7.42. To the left you see an opacity map. The middle figure shows a simple box in VIZ without a material assigned to it. The figure to...
