Modeling volumes

This topic provides recommendations about modeling neighbouring volumes and enclosed volumes:

• Neighbouring volumes
• Enclosed volumes

Neighbouring volumes

When modeling neighbouring volumes such as liquids in basins or different layers of liquids, you can:

• Separate them with a thin layer of air, which will cause additional refraction effects as shown in the following figure:
  Figure 1. Non-overlapping volumes. The layer of air that separates them causes non-realistic refraction effects
  
  
• Slightly overlap them to avoid additional refraction effects as shown in the following figure:
  Figure 2. Overlapping volumes, which shows the physically correct variant
  
  
  A slight overlap is the recommended modeling technique for neighbouring volumes.

Enclosed volumes

When modeling enclosed volumes, no special modeling guidelines need to be considered to ensure correct rendering results. The following line drawing provides a simple example---a glass of water with ice cubes that contain air bubbles:

Figure 3. Ice cubes in the water render correctly with non-overlapping volumes

When modeling the air bubbles, the ice cubes and the water, it is not necessary that these overlap as the air bubbles are enclosed by the ice cubes, which are again enclosed by the water. The glass and the water are neighbouring volumes however, so they should be modeled with a slight overlap.