Lighting concepts

15 Feb

Cinema 4d includes a default light every time you open a new scene. If illuminating a scene were the only function of lighting, there would never be a need to create or edit a light. Artistically, however. light can be used to invoke mood or drama, enhance modelling and spatial depth, paint the scene with colour, influence textures, focus attention, invent magic, and much more. Time spent studying different types f lights and their settings and investigating resources on photographic or theatrical lighting will pay big dividends in the look of your work.

Types of lights:

Omni

Omni light casts light rays evenly in all directions. Placing an omni light in the center of your scene will illuminate your scene evenly. Omni light acts like a real life light bulb.

Spot

Spotlight casts its rays in just one direction, which is along the z-axis by default. The spotlight light source can produce a round or a square cone of light. They can be easily moved and rotated to light individual objects and specific areas of a scene. Spotlight can be used for car headlights and torches amongst other things. They are also ideal for the simulation of a square picture to be cast onto a wall.

Infinite

The Infinite light type is so called because it mimics light that is cast from an infinite distance. Using a Infinite light would, for example, evenly illuminate the whole of a floor (provided the floor is flat). Since a Infinite light is infinite, the light has no actual origin. Thus the exact position of a Infinite light, near or far, has no effect on your scene’s objects. Only the actual direction in which the light is facing is important with this light source. Infinite light sources are suitable for simulating sunlight. The infinite light source itself cannot radiate visible light.

Area

The light rays from an Area light expand from all points on its surface outwards in all directions. A rectangular computer screen is a good example of such a light. The resultant lighting and specular effects are somewhat different from those of an Omni light; specular highlights are more angular and the surface illumination is richer. The closer the light source is to the object, the more apparent this becomes. An area light cannot be rendered as a visible light source.

Parallel

Parallel lights resemble a very distant light source. Unlike the Distant light source however, the Parallel light has an origin and simulates a large, single axis wall of light. By default, all Parallel lights will radiate light rays along the Z axis. These lights take the appearance of an infinitely large surface, radiating parallel light in a single direction; anything behind the point of origin will not be illuminated. Parallel lights cannot be rendered as a visible light. Parallel spotlights resemble the regular spotlight but do not have light cones to define falloff or distance. Instead, light rays are cast along cylinders and/or bars. The origin is important in defining which objects in a scene will be affected by this light. The radius of the spotlight can also be modified using the adjustment handles.

Any of these light sources can be created as a light with a target for easier positioning.

Types of shadow

Shadow Maps (Soft)

In reality all objects — whether they are trees growing in the wild, or a vase in a room — are lit by several partial light sources. The result of this is a gradual transition of light to shadow. This soft edge, or umbra, can be simulated in CINEMA 4D by using a shadow map. A shadow map is a grayscale picture of the scene as viewed from the light source. Contained in this are all the objects lit by the light source. During the render calculation the renderer will determine exactly which objects will fall into this shadow of the light source. The major advantage of this method is the high computing speed and the soft shadow’s natural appearance.
However, the one downside to soft shadows is the memory needed. Depending on the size of the shadow map, a great deal of additional memory may be needed. So be careful in your allocation of shadow maps or you may find your scenes wasting precious memory.By default, a standard size of 250×250 is used. Shadow map size can be increased substantially if needed. In order to keep your shadow sharp and smoothly defined, your shadow map will need to increase in size. If you simply need to keep your shadow edge soft, you can increase the Sample Radius. Again, this will increase render time.

Raytraced (Hard)

Traditionally in raytracers, genuinely raytraced scenes contained hard shadows. As this technique needed to compute many more additional rays, this method increases the render time dramatically. Hard shadows, because of their abrupt, sharp appearance, are of particular interest for technical illustrations. However, in other more natural pictures they look rather unrealistic because such hard, sharp shadow borders are rarely found in real world environments.

Area

Although Soft shadows are more natural than Hard shadows, they are still not perfectly natural. On careful examination you can see that the soft edge always has the same width. In nature this does not happen; the closer an object is to a surface on which it casts its shadows, the sharper this edge will be. Area shadows simulate this effect. Area shadow is the result of a virtual Area light source that simulates the overlay of several light sources. This provides the natural scattering of light. However, as usual, this method comes with a price: it adds to the render time. Carefully assigned Area shadows, however, can produce very realistic shadows.

 

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