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Manual - Blender 2.48

[edit] Spot

Mode: All Modes

Panel: Shading context → Lamp sub-context

Hotkey: F5

[edit] Description

Spot Lamp.

A Spot lamp emits a cone shaped beam of light from the tip of the cone, in a given direction.

The Spot light is the most complex of the light objects and indeed, for a long time, among the most used thanks to the fact that it was the only one able to cast shadows. Today, with the integration of a ray tracer within the internal render engine of Blender, all lamps can cast shadows (except Hemi). Even so, Spot lamps’ shadow buffers are much faster to render than raytraced shadows, especially when blurred/softened, and spot lamps also provide other functionality such as “volumetric” halos.

[edit] Options

Lamp Panel.

Common options: The Dist:, Energy and Color settings are common to most types of lamps, and are described here.; The Layer, Negative, No Diffuse and No Specular settings control what the lamp affect, as described in this page.

Spotlight with Dist value of 20.

Spotlight with Dist value of 10.

Changing the Dist: field value when using a Spotlight also changes the appearance of the Spotlight as displayed in the 3D Viewport:

Light attenuation drop-down list and Sphere button: These settings control how the light of the Lamp decays with the distance. See this page for details.

[edit] “Shadow and Spot” Panel

When a Spot lamp is selected the following default layout for the Shadow and Spot Panel is shown:

Without shadow.	With raytraced shadows.	With buffered shadows.
The Shadow and Spot panel when Spoltlight lighting is selected.

[edit] Options

SpotSi: The SpotSi (SpotSize) Numeric Slider field controls the size of the outer cone of a Spotlight, which largely controls the circular area a Spotlights light covers. It does this by altering the Angle from the position of the Spotlight to the outer cone of the Spotlight. The SpotSi Numeric Slider field represents that Angle. The SpotSi value can be from 1 degree to 180 degrees.

SpotSi settings at 45 and 20 Degrees.

SpotBL: SpotBL (SpotBLur) Numeric Slider field controls the inner cone of the Spotlight. The SpotBL value can be between 0 and 1. The value is proportional and represents that amount of space that the inner cone should occupy inside the outer cone (SpotSi).

3D View of Spotlight with a SpotBL setting of .5.

Render of Spotlight with a SpotBL setting of .5.

The inner cone boundary line indicates the point at which light from the Spotlight will start to Blur/Soften, before this point the Spotlights light will mostly be full strength. The larger the value of the SpotBL the more Blurred/Soft the edges of the Spotlight will be and the smaller the inner cones circular area will be (as it starts to Blur/Soften earlier).

To make the Spotlight have a sharper falloff rate and therefore less Blurred/Soft edges, decrease the value of SpotBL. Setting SpotBL to 0 results in very sharp Spotlight edges with almost no soft edge.

The falloff rate of the Spotlight light is a ratio between the SpotBL and SpotSi values, the larger the circular gap between the 2 the more gradual the light fades between SpotBL and SpotSi.

You can directly control the effective diameter of the Spotlights circle by adjusting the SpotSi property or indirectly by adjusting the Dist: property. The gap between SpotBL and SpotSi remains constant for changes to Dist:.

SpotBL and SpotSi only control the Spotlight cone’s softness or falloff, they do not control the shadow’s softness as shown below.

Render showing the Soft Edge Spotlighted area and the Sharp/Hard Object Shadow.

Notice in the picture above that the “Object’s shadow” is sharp as a result of the raytracing, whereas the Spotlights edges are soft. If you want other items to cast soft shadows within the Spotlights area you will need to alter other settings described below.

Square: The Square button makes a Spotlight cast a square light area, rather than the default circular one.

Spotlight with a Square light area.

[edit] Shadows and Halos

The other options in this panel are about shadows and volumetric effects. The Spot light source supports raytraced and buffered shadows, along with halos, follow these links for in-depth descriptions of these topics.