Lighting, Rendering, Composting
Lights bring life to an object, scene, characters. It plays a pivotal role in defining the look of a scene. It adds visual depth and complexity to a scene, thereby heightening its dramatic impact. It has two purposes which help differentiate 2D models from 3D models.
- It produces shadow which causes the 3D model to appear to be anchored to the ground.
- It adds depth to the model through the use of advanced shading techniques.
When a scene is rendered, modeling, texturing and the whole appearance of the scene is only visible due to lighting. There are various standard lighting options available. Some of them are:
- Point / Omni Light – This is like a normal household light bulb which casts lights in all directions from a single source & has no specific shape & size.
(Point Light, n.d)
- Directional Light – It is the opposite of omni light. It presents a very distant source of light & the rays often go parallel in a single direction eg: sunlight.
(Directional Light, 1997)
- Spot Light – It is a light designed to direct a narrow intense beam of light on a small area. They can be targeted spot light or free spot lights, those which have not specific target object. Eg: desk lamp or a street light.
(Spot Light, 2015)
- Area Light – This is a light that simulates the size of a physical light source in real life. With other types of light, scaling up the light in your scene only scales up the icon, and doesn’t change the illumination whereas if you scale up an area light, it accurately simulates illumination from a larger panel of light. It emits light within a set boundary of a certain size and shape (rectangular or circular). It produces soft-edged shadows that make rendering look more realistic. It is the opposite of directional light as it goes in all directions and do not emit parallel rays.
(Area Light, 2013)
- Volume Light – It is similar to omni light as it casts rays in all directions from a certain point but it has a specified shape and size & illuminates surfaces only within the set volume. It tends to provide the effect of smoke, fog etc.
(Volume Light, 2014)
3D Rendering is the process of producing a 2D image based on three-dimensional data stored within a computer. They are calculations performed by the software’s render engine to translate the scene from a mathematical approximation to a finalized 2D image. During the process, the entire scene’s spatial, textural, and lighting information is combined to determine the color value of each pixel in the flattened image. There are 2 types of rendering, based on the speed at which images are computed & finalized.
- Real-Time Rendering: used most prominently in gaming and interactive graphics, where images are to be computed at a very high speed. The key features are:
- Interactivity: as it’s not possible to predict a player’s actions, the resultant images have to be rendered real-time .
- Speed: Just so there is no break in the fluid motion of the images, the rendering speed required is a minimum of 20 FPS.
- Method: Having a dedicated graphics hardware as well as pre-compiling as much information as possible helps improve render speed. Eg: Pre-baking lighting information into the environment’s texture file helps to render faster in real-time.
- Offline or Pre-Rendering: Offline rendering is used in situations where speed is less of an issue & hence the a dedicated graphics hardware is not required for the same. Some of the key points to be considered are:
- Predictability: There is not unpredictability on what is expected in each frame eg in an animated film. Hence, it can be pre-rendered.
- Photorealism: Since there is no major time limits to rendering, a higher level of photorealism can be achieved as higher resolution textures etc can be use.
Compositing is the creative process of assembling and combining filmed or rendered elements from multiple sources, to create a final lifelike illusion or fantastical visual effect, delivered as a set of still or moving pictures. There are two types:
- Node-based Composting: Shows the composite as a ‘tree’ structure. The media objects and effects are linked together in a procedural map that sets out the process from raw input to the finished product. This is the preferred method for complex composites involving 3D.
- Layer-based Compositing: Each media object in the composite is a separate layer within a timeline. These layers are then progressively rendered one on top of the other.
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