LuxRender Lighting

From LuxRender Wiki

LuxRender supports a variety of lamp types: point lights, spot lights, area lights (also known as emitters) and environment lights. A scene needs to contain at least one light source. Multiple light types can be combined in a

Light Types

Point Lights

Point lights are infinitely small light sources that emit light in all directions. Apart from their location, the only available setting is colour, which can also be used to regulate intensity.

Spot Lights

Spot lights are infinitely small lights that emit light in a cone shape. Apart from colour and location, the width of the cone can be set (in angles), and there is a setting to fade the intensity towards the edge.

Area Lights (emitters)

Area lights are objects that emit light. They can be used to create all kinds of lamps and other glowing objects of various colours. For example, modelling a light bulb and assigning an emissive material to the tunsten wire will result in a realistic light bulb.

Objects only emit light in the direction that the normals of the object's faces are pointing. For rendering speed it is best to use as few faces as possible on emissive objects.
rendering, but there can be at most one environment light.

lighting using an emitter compared to a physical sky

Environment Lights

lighting using HDRI maps (left two images), a physical sky and an infinite environment (right). HDRI maps by Doug Hammond

Physical Sky

The physical sky creates a lighting setup that simulates the light of the sun and atmosphere, based on the direction of a sun lamp in the scene and a parameter named turbidity which defines the clearness of the sky. Both the sun angle and the sky clearness influence the colour of the light.

various sun angles result in different sky and light colours

turbidity settings of 2, 4, 8 and 16, influencing both sky clarity and colour

The intensity of the light can be set with the gain parameter. This can be useful in scenes where a physical sky is combined with emitter lights.

HDR Environment Maps

Environment maps are high dynamic range images that function as a light source. The maps are projected around the scene and emit light; the colour and intensity of the light depend on the local colour of the map.

LuxRender 0.5 only supports latlong images in the OpenEXR (.exr) file format. Latlong images look like a panoramic photo. The development version of LuxRender accepts both latlong and spherical environment maps.

When using environment maps, using a gamma value of 1.0 (instead of the usual 2.2) is recommended.

Background Colour

When using a background colour as a light source, a plain colour will be used to equally illuminate the scene from all sides.

IES data

a number of IES data files

colour and spectrum

todo

rgb

todo

blackbody / colour temperature

todo

a range of colour temperatures. The middle lamp has a colour temperature of 6500K

frequency

todo

gaussian spectrum

todo

lamps emitting light around 589nm, with increasingly wide spectrum

regular data

todo

irregular data

todo

Light Groups

(TODO)