Unity 5 Graphics - Lighting Overview - Unity Official Tutorials [beta 10]

Lighting in Unity 5 is more fully featured than in any previous versions of Unity.

The lighting pipeline now includes Realtime Global Illumination in addition to traditional Baked lightmapping.

This, combined with the physically based Standard Shader, gives you more power and versatility to easily light more complex scenes.

One of the key differences in the lighting pipeline is Unity’s new Realtime Global Illumination or “GI”.

GI is available for all lights working in the scene.

This means that all lights in the scene affect the objects within range with indirect illumination as well as direct illumination.

Direct Illumination comes from the light shining on the objects in the scene.

Indirect Illumination, however, is the light reflected, or bounced off of, other surfaces in the scene.

Direct and Indirect light will blend together to create a much more realistic look.

A new scene in Unity comes with a default skybox

and a default directional light that is aligned with the skybox, in addition to the default main camera.

Each scene also contains ambient light, which can be comprised of a number of factors.

In the Lighting panel’s Scene tab, we have options for ambient light

with a choice of skybox colour

a user defined gradient of 3 colours

or a single colour.

This means that any object added to the scene will receive this light, unless values are set to black.

When lighting scenes in Unity 5, we can work with real-time lighting

baked lighting or a mixture of both approaches.

Real-time lighting is more easily modified at runtime, but comes at a cost to performance.

Baked lighting pre-calculates much more detailed lighting information

and saves it to a lightmap - a texture on disk.

This lightmap information is read from disk at runtime

and this approach avoids the need to do calculations later, saving performance at runtime.

Using Baked lighting exclusively would be more appropriate for devices with lower performance capabilities,

such as mobile platforms.

Lights can be switched between Realtime, Baked and Mixed lighting on a per light basis.

The light mapping system can work in either "Iterative" mode, or "On Demand" mode.

Iterative mode will bake any lighting changes in the background as you edit properties.

On Demand mode will only preview changes once the "Bake" button in the Lighting panel has been selected

in a similar way to how previous versions of Unity functioned with baked lighting.

In this scene, we have a directional light coming in through the sky light at the top

casting shadows that you can see around the chamber area from the furniture inside.

This light contributes to the illumination for the rest of the scene

because it bounces from the surfaces it lights directly onto others.

If I decrease the intensity of this light, you can see the illumination of the room decreases also.

Likewise if we simply rotate the directional light

you can see that as it has moved to directly light a different part of the scene

we can see the light now bounces to illuminate the ceiling more effectively.

The rest of the room is lit with Point and Spot lights as well as Emissive surfaces.

This means that we can give our scene a very different feel by changing some of the colour values in the contributing lights.

As these elements are part of the realtime lightmapping

we can also control these lights at runtime using coding or animation.

This allows us to create complex changes in mood during our games and projects.

As the new standard shader can mimic a wide array of physical surfaces in your projects

you can expect certain materials to have different amounts of reflectivity as far as light is concerned

To help balance this, you can either adjust Bounce Intensity on a per light basis

or globally using the settings in the Lighting Panel.

Albedo scale lets you artificially increase the potential bounce for dark scenes.

Indirect scale allows you to boost or decrease indirect light in the scene for realtime and baked lightmaps.

Direct scale allows you to boost the light in baked lightmaps.

AO Exponent controls the amount of Ambient Occlusion and also only applies to baked lightmaps

allowing you to darken bounced lighting in occluded areas.

In addition to lights, we can use Emissive surfaces to contribute to lighting.

In this scene we can see a lit panel around the ceiling of the room

and various strips of geometry in the wall panels

all of these utilise the standard shader’s Emissive property

You can see that by adjusting the emission scale - the float value next to the property -

and adding a touch of colour, we can vastly change the mood of our scene.

The final contributory factor in lighting your Unity scenes are Probes.

There are now two types of Probe in Unity - Light and Reflection probes.

Light probes function in much the same way as in previous versions of Unity,

acting as a grid of points via which you can sample the light at different positions in the world,

and cast it upon dynamic objects such as characters and other moving elements, with low performance cost.

Reflection probes act as a single point of reference for reflection,

with an accompanying cubic volume to allow you to specify what should be included in the reflection.

These probes sample elements surrounding them using box projection

and store the information in a cubemap.

Materials with reflective shaders that are on objects within the Reflection probe’s volume,

can then reference that cubemap to create reflective surfaces.

As such, you should keep this in mind when designing the lighting of your scenes,

as the reflectivity of surfaces should be factored into the overall lighting.

So ultimately, lighting in Unity 5 is a balance of ambient light, direct and indirect light and reflections.

For more information on the new lighting systems in Unity 5, please see the information linked below.