Three-dimensional computer graphics

three-dimensional computer graphics (3D computer graphics) are works created with the help of computers and special three-dimensional software. Generally speaking, the term can refer to the process of creating these graphics, or three-dimensional computer graphics technology research field, and related technologies.

The difference between three-dimensional computer graphics and two-dimensional computer graphics is that computer memory stores three-dimensional representations of geometric data, which are used to calculate and draw the final two-dimensional images.

Generally speaking, the three-dimensional computer graphics for the preparation of geometric data modeling the art and sculpture and photography similar, and two-dimensional computer graphics similar to the art and painting. However, three-dimensional computer graphics rely on many of the same algorithms for two-dimensional computer graphics.

In computer graphics software, the distinction is sometimes blurred: some two-dimensional applications use three-dimensional techniques to achieve specific effects, such as lighting, while some applications that are primarily used for three-dimensional application use two-dimensional visual techniques. Two-dimensional graphs can be considered as a subset of three-dimensional graphs.

Technology

OpenGL and direct three-dimensional are two popular APIs for generating real-time images. (Real-time representation of the image is generated in "real time", or "anytime"). Many modern graphics cards provide a certain level of hardware acceleration based on these APIs, often making complex three-dimensional images real-time. However, the real three-dimensional scene does not have to use any one of them.

the creation of three-dimensional computer graphics

The process of creating a three-dimensional computer graphic can be divided into three basic stages:

• Modeling
• Scene layouts and animations
• Draw

Modeling

The modeling stage can be described as "determining the shape of the object to be used in a later scene." There are many modeling techniques that they include (but not just):

• Constructing solid geometry
• NURBS Modeling
• Polygon Modeling
• Subdivision surface
• implicit function surfaces

The modeling process may also include editing an object's surface or material properties (for example, color, fluorescence, diffuse and specular components-often called roughness and finish, reflective properties, transparency or opacity, or refractive index), adding textures, bump maps, and other features.

Modeling may also include various activities related to the three-dimensional model of preparing animations, sometimes in complex task modeling, which will itself become a stage called rigging (rigging). Objects may be propped up with a ' skeleton ', a central frame of an object that can affect the shape or movement of an object. This is useful for the animation construction process, and the skeleton can automatically determine the relevant parts of the model. See positive motion animations and inverse motion animations. In the rigging phase, the model can also be given a specific control, making movement control easier and more intuitive, such as facial expression control and mouth-shaped (phoneme) for voice lip synchronization. Modeling can be used for this purpose-designed program (e.g. Lightwave modeling software, rhinoceros three-dimensional, Moray), applied modules (Shaper, three-dimensional Studio max Lofter) or some scenario description language (such as Pov-ray). In some cases, there is no strict distinction between these phases, in which case the modeling is only part of the scene creation process (for example, Caligari truespace is the case).

Triangulation and grids

Converting an object's representation (such as a spherical surface represented by a point on the center of a sphere) to a polygonal representation of (a spherical polygon), called a split (tesselation). This step is used for polygon-based drawing, where objects from such abstract representations as spherical, conical, and so forth ("voxel"), are decomposed into so-called "meshes", which are interconnected triangles of the network.

Triangular meshes, rather than squares, are popular because they are easy to draw with scan lines.

Polygon representations are not required for all drawing techniques, and in these cases the transformations from the abstract representation to the plotted scene do not include the split step.

Scene Layout Settings

Before rendering into an image, the model must be placed in a scene. This defines the location and size of the model.

Scene settings involve arranging virtual objects, lights, cameras, and other entities within a scene, which will be used to make a static picture or a piece of animation.

Illumination is an important aspect in the layout of the scene. As in the actual scene layout, lighting is one of the key factors in the aesthetic and visual quality of the final work. Thus, it is a difficult art to master. Lighting factors can make a significant contribution to the mood and emotional reflection of a scene, a fact that is familiar to photographers and stage lighting artists.

Set Animation

Main article: Computer animation

Animation is a description of the change in the model over time. Common methods include setting keyframes, motion snapping, skeletal animation, and inverse kinematics (IK), which are often used in conjunction with these techniques.

Rendering

Rendering is the final stage of creating an actual two-dimensional scene or animation from a prepared scene. This can be compared to the real-world process of photographing or filming scenes after a scene has been completed.

Rendering of interactive media such as games or simulations requires real-time computation and display at speeds of approximately 20 to 120 frames per second. Non-interactive media (such as video or movie), renders much slower. Non-real-time rendering allows limited computing power to be amplified for high-quality images. A single frame of a complex scene can render at speeds from a few seconds to one hours or more. The rendered frame is stored on the hard disk and can then be transcribed into other media, such as a film roll or disc. These frames are then played at a high frame rate, usually 24, 25, or 30 frames per second to achieve the illusion of movement.

The final work will often need to achieve a realistic graphics quality, to achieve this goal, many different and specialized rendering technology has been developed. These technologies range from fairly non-photorealistic wireframe model rendering techniques to polygon-based rendering to more advanced techniques such as scanline rendering, ray tracing, or radiation coloring.

Rendering software can simulate visual effects such as lens flares, depth of field, or motion blur. These techniques attempt to simulate the visual phenomena caused by the optical properties of the lens and the human eye. These techniques can increase the realism of the scene, although the effect may be just a man-made simulation of the lens.

Various techniques for simulating other naturally occurring effects have been developed, such as the interaction of light and different forms of matter. Examples of these techniques include a particle system (which simulates rain, smoke, or fire), body sampling (used to simulate fog, dust, or other atmospheric effects), caustics (used to simulate a phenomenon in which light is focused on a surface that is not uniformly refracted, such as a ripple of light at the bottom of the pool), There is also a secondary surface scattering (subsurface scattering) (used to simulate the phenomenon of light reflecting inside a body object such as a human skin).

The rendering process is computationally expensive, especially when the physical processes being simulated are complex and diverse. The ability of the computer to handle the process has risen every year, making the quality of realistic rendering progressively improved. Movie studios that produce computer animations may use render farms to render in a timely manner. However, the decline in hardware costs has made it possible to produce a small number of three-dimensional animations on a home computer system.

Renderers are often included in three-dimensional packages, but some render systems are used as plug-ins for popular three-dimensional applications. These rendering systems include Final-render,brazil R/s,v-ray,mental Ray,pov-ray, and Pixar Renderman.

The output from these renderers is often used for a fraction of the final movie scene. Many layers of material can be rendered separately and then integrated into the final picture using synthetic software.

reflection and Shading models

Modern three-dimensional computer graphics are heavily dependent on a simplified reflection model called the Phong reflection Model , which is a completely different subject than the Phong, and cannot be confused.

In the refraction of light, there is an important concept called refractive index. In most three-dimensional programming implementations, the value "Index of refraction" (refractive index) is usually abbreviated as "IOR".

An example of a straight coloring, a three-dimensional painting of the Dunkirk battleship

Popular reflection rendering techniques in three-dimensional computer graphics include:

• Straight coloring (Flat shading): a technique that uses the method vectors and positions of polygons and the position and intensity of the light source to give a shading value to each polygon of an object.
• Gouraud coloring: H. Invented in 1971, Gouraud is a fast coloring technique based on vertex-and light-source relationships for simulating smooth-shaded surfaces.
• Texture mapping: A technique for simulating a large amount of detail of a surface by mapping an image (texture) to a polygon.
• Phong coloring: Invented by Bui Tuong Phong, used to simulate the specular highlight effect of smooth shaded surfaces.
• Concave-convex texture mapping: Invented by Jim Blinn, the use of the perturbation technique to simulate a wrinkled surface.
• CEL coloring: A technique for simulating the look and feel of hand-drawn animations.

Three-dimensional Graphics application interface (API)

Three-dimensional graphics are very popular, especially in video games, which allows specialized application interfaces (APIs) to be created to simplify the processing of all phases of computer graphics generation. These APIs are also extremely important for computer graphics hardware vendors, because they provide programmers with a way to use hardware abstractions, while still being able to leverage the strengths of the specific hardware of that video card.

These three-dimensional computer graphics APIs are quite popular:

• OpenGL and OpenGL coloring languages
• Three-dimensional API for OpenGL es embedded devices
• Direct three-dimensional (subset of DirectX)
• RenderMan
• RenderWare
• Feekood

There are also high-level, three-dimensional scenario map APIs that provide additional functionality on top of the underlying drawing API. Such libraries, which are in active development, include:

• Qsdk
• Quesa
• Java three-dimensional
• JSR 184 (M3G)
• NVidia Scene Graph
• OpenSceneGraph
• Opensg
• Wooyoo
• Ogre
• Irrlicht

Three-dimensional computer graphics