Principles and Conventions in 3D for Film and Game Design

3D animation is the process involving creation of moving 3D computer-generated imagery (CGI). 3D animators are responsible for the description of behavior and movement. It is most often applied to give life of characters such as human beings or creatures. 3D animations could also be applied to elements such as objects, environments, scenery and vegetation. Depending on the technology, 3D animators make best use of it in order to create the animation in an efficient way. They, also, maximize the opportunities for interactivity for a particular platform.

There are different 3D software such as Autodesk 3ds Max, Maya, AutoCAD, Cinema 4D and Softimage.  Autodesk 3ds Max software is used by game developers, visual effects artists, and motion graphics artists along with other professionals working in the media design industry. AutoCAD is used by architects, designers, engineers and project managers in building and manufacturing industries. Maya software is used especially in film, television and game industries. Cinema 4D software is suitable for professionals. It is used in the fields such as films, television, architecture, which requires professional results. In comparison to Maya, it is faster and more power. Softimage software is predominantly used in film, TV and game industries with high 3d and visual effects performance. File formats of the software are accordingly .3ds, .mb, .dxf, .c4d and .obj.

3D models of objects are created in three-dimensional space through specialised software. Polygonal modelling is an approach for creating 3D objects by representing their surfaces, using polygons. A polygon mesh incorporates vertices, edges and faces which represent solid objects. Vertex is the basic object used in mesh. Two vertices connected by a straight line form an edge.  Three vertices connected to each other by three straight lines form a basic polygon or face. More complex polygons consist of four and more vertices and edges. Triangles and four sided polygons are the most common polygons used in polygonal modelling. A group of polygons connected to each other form a mesh. Surfaces or smoothing groups are the group of polygons in polygon mesh which create a smooth surface.

Three-dimensional space consists of three coordinate axes, which are commonly labeled as x, y and z. They are, also, perpendicular to each other. Every point in three-dimensional space is described by the coordinates x, y and z. Two-dimensional space consists only from the coordinates x and y. It does not have the z coordinate which represents the depth of the object.

There are several ways of creating a mesh such as box modelling, extrusion modelling, spline modelling and common primitives. Box modelling is a technique in 3D modelling where a primitive shape is modified in order to be created the final object. This technique is utilised in combination with extrude and subdivide functions. Extrude function create a new primitive from the face of a model with the same shape and size of that face. Subdivide function creates more vertices on a model. Therefore, it is split into more face and can be easily modified. Extrusion modelling is a technique where a 3D modeller creates a 2D shape, commonly created with the line tool, which traces outline of a drawing. Then, the 2D shape is extruded into 3D shape. This process applies to all of the sides of the drawing. Spline modelling is a technique where you use splines with various functions such as lofting and lathing. Splines can be easily created and manipulated due to its curve design. These functions convert a spline into a 3D shape. Primitives are predefined polygonal meshes created by the 3D software. They can be easily created by the modeller and be a starting point of the modelling process.

Wireframe is a method in 3D computer graphics which present a mesh with its characteristics such as vertices and edges. There are a great number of reasons to use this method. Firstly, it reduces rendering time. Eventually, if you want to achieve fully detailed model, you have to switch to a solid mode of it. Also, it is very useful method when you present a few concept ideas. Therefore, you will safe your time not to design fully composed 3D models. Wireframe allows seeing through the object and easier to modify it. It is, also, useful when you want to reduce the number of polygons of the object in order to simplify it and reduce rendering time.

OpenGL is a cross-language and multi-platform application programming interface (API) for rendering 2D and 3D images. It incorporates a great number of functions which implement processes such as rendering, texture mapping and visual effects. The PlayStation 3 game console has an OpenGL implementation. OpenGL’s competitor, Direct3D is an API available for Microsoft Windows operating systems. Also, it can be implemented on other platforms using an open source software Wine. Direct3D is used for rendering 3D graphics. It has embedded versions used in the Xbox family of video game consoles.

Computer graphics pipeline is the process that goes from an idea to the fully realised 3D model. This process incorporates six phases: pre-production, 3D modelling, shading and texturing, lighting, animation and rendering and post-production. Pre-production phase includes all of the sketches, paintings, colour palette and details of the 3D model. When the model concept is ready, a 3D modeller translates a 2D drawing into 3D model. There are two major techniques for modellers: polygonal modelling and digital sculpting. Polygonal modelling is suited for architectural modelling, while digital sculpting for organic modelling. The next step in the pipeline is the shading and texturing phase where colours, materials and textures are added to the 3D model. In the lighting phase, digital light is added to the 3D scene to illuminate models. Then, animators have to bring to life 3D characters and environment. There are two animation techniques: Rigged for Motion and Pose-to-Pose. The first technique incorporates virtual skeleton which controls the motion of the model. The second one incorporates a set of key-frames with different poses of the model which will create the illusion of motion. The final phase incorporates finalising shadows, adjusting colours, brightness or contrast as well as integrating special effects to the scene.

A rendering process is performed by 3D software package’s render engines. It translates a mathematical representation of a 3D object to a 2D image. The colours of the image are determined by the lighting, spatial and textural information of the scene. There are two major types of rendering: Real-time rendering and Pre-rendering. Real-time rendering is suitable for interactive graphics and gaming where visualisation of 3D models is unpredictable. Its speed of computing a 3D object or environment in “real-time” is rapidly fast. Pre-rendering is most frequently seen in animations and visual effects where the speed is not so important. It can achieve a high level of photorealism and visual complexity.

There are three rendering techniques: Scanline, Raytracing and Radiosity. Scanline technique produce a very fast rendering which is a best choice for real-time rendering. It renders polygon by polygon instead of pixel by pixel. Raytracing is slower than Scanline, but produce an image with higher photorealism. It is based on pixel by pixel rendering. Radiosity is a surface oriented rendering technique. It is known with soft shadow, colour bleeding and subtle lighting effects.

There are two most common rendering engines: Mental Ray and V-Ray. Mental Ray is packaged with Autodesk Maya. It uses combination of both radiosity and raytracing rendering techniques. It is characterised with its relatively fast speed and producing scattering light on a surface. V-Ray is packaged with Autodesk 3ds Max. It is suitable for architectural and environment rendering.

Level of detail is reducing complexity of the object and increasing efficiency of rendering process. The change of the model is unnoticeable and can be hidden by the motion of the object.