NGon Light

Normalize

There is a Normalize toggle in most Light Properties windows. Light intensity is now set in Lux, which is Lumen per meter squared. This means that as your lights change size so does their intensity. With Normalize off, a smaller light of a given intensity will give out less light, a bigger light more. With Normalize on, the intensity stays the same. It might appear to become dimmer in some cases but this is merely because the light output is being spread over a larger area.

The area of a Distant light will decrease as you reduce the angle in the panel, and thus its power diminishes if Normalize is not checked. 0° is a special value, and the Distant light will behave the same Normalized or not, with hard shadows.

Portals

Light Portals.7z

tip

For copyright reasons, a gradient has replaced the HDR image for this scene. The effect is more interesting with a proper HDR image.

Area and NGon lights can be used as portals. Portal lights are guides placed in indoor scenes that help the renderer to concentrate environment lighting through openings like small windows.

Portals work with the environment light and its plugins - Image World, Textured Environment, gradient backdrop or similar. While portals will add time to renders they also clear up noise and bring a lot of extra detail that you don't get using an environment light alone.

tip

The reason for turning Normalize off when using a portal light is that the color and intensity are coming from the backdrop environment rather than a localized light source. As such, the size of the portal has no bearing on the quality of light coming through the opening and so Normalize is turned off automatically when Portal is engaged. Normalize can be turned back on for artistic reasons.

note

If your scene has multiple lights, or large openings for light to come in from the environment, using a portal is not necessary - it can unnecessarily slow down rendering and even create additional noise. Equally, complex material networks will benefit from direct lighting rather than the additional computation necessary for portals. Finally, if you have several small openings on a wall, consider using a single portal that spans them all instead of multiple portals that can increase render setup time.