Monday, March 21, 2011

Lighting Research Essay

Three-point lighting

Three-point lighting is the customary lighting technique used in most visual media. It consists of three lights “called the key light, the fill light and the back light” (

The key light “represents the most dominant light source, such as the sun, a window, or ceiling light – although the Key does not have to be positioned exactly at this source” (3D Therefore the key light will create “the subjects main illumination, and defines the most visible lights and shadows… and creates the darkest shadows” (3D

Jeremy Birn suggests that one uses a spot light for the key light and that you offset the Key Light 15 to 45 degrees to the side of your camera, from the top view. From a side view, he says, that you should raise the Key Light above the camera also 15 to 45 degrees (3D

The purpose of the Fill light is to soften and extend “the illumination provided by the key light, and makes more of the subject visible” (3D While the key light creates the most dominant light source the Fill light will create any secondary light source such as “the sky (other than the sun)… table lamps or reflected and bounced light in your scene” (3D According to Birn the best choice of light for a Fill light is a spot light however one could use a point light (3D

In terms of the placement of the Fill Light, one should place it on the opposite side to the Key Light, however one should not place them exactly symmetrical to each other (3D

Because the Key Light is the predominant light in the setup the “Fill Lights can be about half as bright as your Key (a Key-to-Fill ratio of 2:1), [however if one wanted to create] a more shadowy environment, use only 1/8th of the Key’s brightness (a Key-to Fill ratio of 8:1) (3D

However when it comes to creating shadows from a Fill light they are optional and predominantly not used. Yet to “simulate reflected light, tint the fill colour to match the colours from the environment. Fill lights aare sometimes set to diffuse-only (set not to cast specular highlights)” (3D

Finally there is the Back Light, which is also known as the Rim Light, “creates a bright line around the edge of an object, to help visually separate the object from the background” (3D

When placing the Back Light, from the top view, “position it behind your subject, opposite from the camera. From the right view, position [it] above your subject” (3D

How bright one decides to make a Back Light is dependant on how strong one wants the highlight on an object. Usually a Back Light will cast shadows. A Back Light will often be linked to the object which one is lighting so that it seperates it from the background (3D

This lighting rig is the most commonly used one as it can be used to light almost any scene or object. Furthermore due to the use of the three light all placed at different angles one has absolute control of how the light will look from each angel.

Creating Reflective Studio Light Set up (Taken from Digital Tutors tutorial on “Creating a Studio Light Setup in Softimage)

This Light set up is made up of 2 lights, a Key and a Fill Light. Additionally there are 3 reflectors, one of which acts as a skydome for added indirect illumination.

Initially one will create the Key light, for this light setup a Box Light is the best choice. As a Box Light allows one to create soft shadows. In order to create the desired soft shadows set the umbra value to 0 and then adjust the Area Transformation scaling to 30, for both the x and the Y values. It is through increasing this scaling that one can create softer shadows. For this particular light set up the Key light will be placed behind the object. As this light is our main light source the light intensity can be set to 0.75.

Next one will create the Fill Light, which will have the same settings as the Key Light in terms of the umbra and Area Transformation scaling. However as the Fill Light is a secondary light source the light intensity will be set to 0.5. The Fill light will be placed in front of the object.

Although there are two light sources in the scene, which are responsible for creating shadows, there is no evidence of direct light sources, which are creating reflections. This can be achieved through creating reflectors/diffusers.

To create the reflectors simply draw it using the ‘Draw Cubic by CV tool’. Duplicate the curve, move the duplicate along and create a loft surface mesh. It may be necessary to raise the U subdivisions as to create a smoother surface. The best material to mimic the effect of a light-emitting surface is a constant. Therefore one will apply this material to the object and set the colour to white.

Depending on the object, which you are lighting, and how you would like the reflections to be positioned, one can move the reflector around until it looks right. Additionally a secondary reflective source may be necessary to achieve the required results. In order to adjust the brightness of the diffuser one must change the HSV V component to a higher value, in this case to 3.

At this point the object possesses both shadows and reflections. However the over all lighting of the object is still quite dark. As seen, in the screen shot, bellow.

This can be overcome by adding some secondary illumination. In order to do this one must initially enabling final gather. While this will lighten the object significantly it lights it in an overall manner. Therefore if one creates a dome around all of the objects and applies a graded constant material, which grades from white to black, the secondary illumination to reflect mainly from the bottom part of the dome therefore only effecting the bottom section of the object and leave the top of the object to be light by the two diffuses and light previously set up in the scene.

Works Cited

3d Three-Point Lighting for 3D Renderings. Jeremy Birm. Web. 17 March 2011

Digital Tutors. Creating a Studio Light Set Up in Softimage. PL Studios. 2009. 21 March 2011.

Media The Standard 3-Point Lighting Technique. Np. Web. 17 March 2011

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