In this Blender tutorial, we’ll take a look at how simple it is to drastically effect the look and feel of your renders by applying textures to lighting. Applying a texture to a light is generally the same as applying a texture to an object. The only difference is that we’ll be projecting the texture into the scene based on the light settings.

Although not a lighting tutorial that goes into great details of the lighting setups, we will take a look at the basic function of the lights within the different scenes. We’ll also cover how to create your own simple textures for the lighting. The last example will show how simple it is to use a video as a light texture.

These techniques will allow you to create interesting light and shadow patterns that can help frame the “story” and context of your scene; thus helping you to create scenes that no longer appear to exist within the all too common CG vacuum. They will also allow you to add subtle variations to your lighting instead of the ultra-clean lighting often seen when using very basic lighting techniques.

This tutorial requires a knowledge of the basics of applying a texture to an object in Blender.

(To help control the length of this tutorial, the blend file for each example in the tutorial will be available for download. This will allow you to get complete details on the scenes and lighting setups.)

Origins

The idea of using artificial light and shadow patterns comes from lighting practices used in live theatre. These practices are also prevalent in cinematography and still photography.

Terminology

In a non-CG environment, the use of these techniques involves the use of gobos and cookies.

A gobo is a template or pattern cut into a circular plate used to create patterns of projected light. The name may be derived from go between, or from Goes Before Optics. Go between refers to its position between the lamp and the lens. Another origin may be: Graphical optical blackout. Gobos are similar in use to cookies (see cucoloris), and flags, which are placed farther from the lighting instrument between the lens and subject. (from Wikipedia: Gobo (lighting) )

In lighting for film, theatre and still photography, a cuculoris (occasionally also spelled cucoloris, kookaloris or cucalorus) is a device for casting shadows or silhouettes to produce patterned illumination. The word is sometimes shortened to cookie or coo-koo. The cookie is used to create a more natural look by breaking up the light from a man made source. It can be used to simulate movement by passing shadows or light coming through a leafy canopy. (from Wikipedia: Cucoloris)

These terms carry over into CG, but are also known as throw, throw patterns, light textures, projected textures, and probably a few other names as well. I’ll be referring to this as a light “texture” because it relates directly to what you have to do in Blender to achieve the same results.

Let’s Begin!

First, let’s take a look at the basic scene and its lighting.

The lighting is a very basic setup consisting of Area lights. The Area lights underneath the Suzanne (monkey) model and the Sphere were added to provide a small amount of bounce light underneath the objects. All of the lights have rather low Energy values.

The scene is also set to render with Approximate Ambient Occlusion (AAO) using the settings as shown. The Sky Color option is selected so that the World color can be used to add a subtle warmth to the overall lighting effect created by the AAO.

Example 1

This first example really doesn’t use a texture light, but I thought it fit well into the same purpose of using a light texture. This was created using an additional Spotlight slightly angled toward the back wall. It’s purposes are to help direct the viewer’s eye toward the subject(s), create more interest, add more contrast between the foreground objects and the background, and to give a better sense of there being a “world” that exists off-camera by giving the illusion of light entering through an opening.

The actual lighting setup can be seen below. The lights described are highlighted in green. Number 1, is the Spotlight already mentioned. Number 2, is an Area light that was added to allow me to control the brightness of the “window” effect at its beginning, independent of the Spotlight. Number 3, is another Area light that’s scaled to cover the area where light cast by the Spotlight meets the floor. This light serves as bounce lighting. Number 4, is a Spotlight serving a dual purpose of bounce lighting and as a rim light for the Sphere and Suzanne objects.

Also, the two original bounce lights on the floor were brightened a very small amount.

Example 2

This example was created using one additional Spotlight, textured with a rendered image from Blender.

The lighting setup is very simple, as seen below. Number 1, is a Spotlight added to the basic scene and it serves as both the key light and the means for projecting the light’s texture into the scene. Number 2, is an Area light used for adding bounce lighting coming from the wall.

As mentioned earlier, the light’s texture was created from a Blender render. The setup was a very basic model of a window structure (Number 3, above) with the Camera (Number 4) set to render Orthographic. The new Camera and window model reside on Layer 3. This technique can be used to create light textures from any model(s). The trick is to be sure to add a Shadeless black material to your object(s) and set the output format to PNG with RGBA enabled, as shown below. Also note that the color black will block light while any other color values will offer degrees of opacity. The white aspect of the light texture will be completely transparent, allowing all light to enter the scene.

After creating the texture image, you’ll need to apply it to the light just as you would apply a texture to a mesh object. However, be sure to set it to use view coordinates for the texture coordinates so that it gets projected correctly.. You can do this by enabling the “View” option as shown below. You can make adjustments to the scale of the texture by using the sizeX and sizeY controls.

You can control the softness of both the projected light texture and the shadows created by the Spotlight by adjusting the controls highlighted below. Adjusting the Filter parameter of the light’s texture controls the blurring of the projected texture.

Here’s a render of the same scene with softened shadows.

Example 3

Just about any material or texture can be applied to a light, including images and any of the procedural textures available in Blender. The exception would be uv-mapped textures because, obviously, you would need actual geometry for that type of mapping. In this next example, we’ll look at the results of using a simple leaf pattern texture created in Photoshop.

The lighting setup consists of two extra lights added to the basic setup. Number 1, is a Spotlight serving both as a key light and as the projector of the leaf pattern. Number 2, is an Area light that’s used to simulate extra bounce lighting from a particularly bright area on the floor.

This is the leaf pattern created for the light texture. It took less than a minute to create this using a custom brush in Photoshop. However, it still functions well as a light texture to add some extra visual appeal to a render. This is a good example of how the different color values (or gray values in this instance) translate to different degrees of opacity when used for a light texture.

In this render, the shadows have been softened using the same techniques covered in the previous example.

Example 4

This final example demonstrates the results of using a video for a light texture. This opens up a whole world of creative opportunities for animated lighting effects! The video used for the texture is a low-res shot of disco lights (not included in the download).

The lighting setup for this scene involves modifications to just about all of the basic lights, and some additions. The AAO setting has been adjusted from Add mode to Sub mode. This causes the AAO to subtract light from the scene. The colors of the original lights have been changed to give more of a nightclub feel, and the single overhead Area light has been replaced with three smaller Area lights. Number 1, is set to a blue color. Number 2, is set to a green color. Number 3, is set to a yellow color. Numbers 4 and 5, are both projecting the same video clip into the scene. Number 6, is an Area light functioning as a fill light to help bring out a little more detail at the floor-level.

To apply a movie as a texture, load it as an Image texture. Then, be sure that the Movie option is set so Blender will recognize it as a movie and not just an image of the first frame in the movie. For this example, I also used different Starting Frames (StartFr) for each of the two lights so they wouldn’t be projecting the same imagery into the scene. I also set the Cyclic option so that the video would automatically loop if the number of rendered frames happened to be more than the number of frames in the movie file.

This concludes this tutorial on using light textures in Blender. I hope this will spur your creative juices to experiment with enhancing your Blender scenes with interesting lighting effects.