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3D computer graphics 3D computer graphics, or “3D graphics,” sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for th ...
, 3D modeling is the process of developing a mathematical coordinate-based representation of any surface of an object (inanimate or living) in
three dimensions Three-dimensional space (also: 3D space, 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called '' parameters'') are required to determine the position of an element (i.e., point). This is the inform ...
via specialized software by manipulating edges, vertices, and polygons in a simulated 3D space. Three-dimensional (3D) models represent a physical body using a collection of points in 3D space, connected by various geometric entities such as triangles, lines, curved surfaces, etc. Being a collection of data (
points Point or points may refer to: Places * Point, Lewis, a peninsula in the Outer Hebrides, Scotland * Point, Texas, a city in Rains County, Texas, United States * Point, the NE tip and a ferry terminal of Lismore, Inner Hebrides, Scotland * Points ...
and other information), 3D models can be created manually,
algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
ically ( procedural modeling), or by scanning. Their surfaces may be further defined with texture mapping.


Outline

The product is called a 3D model. Someone who works with 3D models may be referred to as a 3D artist or a 3D modeler. A 3D Model can also be displayed as a two-dimensional image through a process called 3D rendering or used in a computer simulation of physical phenomena. 3D Models may be created automatically or manually. The manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting. The 3D model can be physically created using 3D printing devices that form 2D layers of the model with three-dimensional material, one layer at a time. Without a 3D model, a 3D print is not possible. 3D modeling software is a class of
3D computer graphics 3D computer graphics, or “3D graphics,” sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for th ...
software used to produce 3D models. Individual programs of this class, such as SketchUp, are called modeling applications.


History

3D models are now widely used anywhere in  3D graphics and 
CAD Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve c ...
but their history predates the widespread use of 3D graphics on 
personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or te ...
s. In the past, many  computer games used pre-rendered images of 3D models as  sprites before computers could render them in real-time. The designer can then see the model in various directions and views, this can help the designer see if the object is created as intended to compared to their original vision. Seeing the design this way can help the designer or company figure out changes or improvements needed to the product.


Representation

Almost all 3D models can be divided into two categories: * Solid – These models define the volume of the object they represent (like a rock). Solid models are mostly used for engineering and medical simulations, and are usually built with constructive solid geometry * Shell or boundary – These models represent the surface, i.e. the boundary of the object, not its volume (like an infinitesimally thin eggshell). Almost all visual models used in games and film are shell models. Solid and shell modeling can create functionally identical objects. Differences between them are mostly variations in the way they are created and edited and conventions of use in various fields and differences in types of approximations between the model and reality. Shell models must be manifold (having no holes or cracks in the shell) to be meaningful as a real object. In a shell model of a cube, the bottom and top surface of the cube must have a uniform thickness with no holes or cracks in the first and last layer printed. Polygonal meshes (and to a lesser extent subdivision surfaces) are by far the most common representation. Level sets are a useful representation for deforming surfaces which undergo many topological changes such as fluids. The process of transforming representations of objects, such as the middle point coordinate of a
sphere A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is the c ...
and a point on its
circumference In geometry, the circumference (from Latin ''circumferens'', meaning "carrying around") is the perimeter of a circle or ellipse. That is, the circumference would be the arc length of the circle, as if it were opened up and straightened out ...
into a polygon representation of a sphere, is called
tessellation A tessellation or tiling is the covering of a surface, often a plane, using one or more geometric shapes, called ''tiles'', with no overlaps and no gaps. In mathematics, tessellation can be generalized to higher dimensions and a variety of ...
. This step is used in polygon-based rendering, where objects are broken down from abstract representations (" primitives") such as spheres, cones etc., to so-called ''
meshes A mesh is a barrier made of connected strands of metal, fiber, or other flexible or ductile materials. A mesh is similar to a web or a net in that it has many attached or woven strands. Types * A plastic mesh may be extruded, oriented, exp ...
'', which are nets of interconnected triangles. Meshes of triangles (instead of e.g. squares) are popular as they have proven to be easy to rasterize (the surface described by each triangle is planar, so the projection is always convex); . Polygon representations are not used in all rendering techniques, and in these cases the tessellation step is not included in the transition from abstract representation to rendered scene.


Process

There are three popular ways to represent a model: * Polygonal modeling – Points in 3D space, called ''vertices'', are connected by line segments to form a polygon mesh. The vast majority of 3D models today are built as textured polygonal models, because they are flexible, because computers can render them so quickly. However, polygons are planar and can only approximate curved surfaces using many polygons. * Curve modeling – Surfaces are defined by curves, which are influenced by weighted control points. The curve follows (but does not necessarily interpolate) the points. Increasing the weight for a point will pull the curve closer to that point. Curve types include nonuniform rational B-spline (NURBS), splines, patches, and geometric primitives * Digital sculpting – Still a fairly new method of modeling, 3D sculpting has become very popular in the few years it has been around. There are currently three types of digital sculpting: Displacement, which is the most widely used among applications at this moment, uses a dense model (often generated by
subdivision surface In the field of 3D computer graphics, a subdivision surface (commonly shortened to SubD surface) is a curved surface represented by the specification of a coarser polygon mesh and produced by a recursive algorithmic method. The curved surface, ...
s of a polygon control mesh) and stores new locations for the vertex positions through use of an image map that stores the adjusted locations. Volumetric, loosely based on voxels, has similar capabilities as displacement but does not suffer from polygon stretching when there are not enough polygons in a region to achieve a deformation. Dynamic tessellation, which is similar to voxel, divides the surface using triangulation to maintain a smooth surface and allow finer details. These methods allow for very artistic exploration as the model will have a new topology created over it once the models form and possibly details have been sculpted. The new mesh will usually have the original high resolution mesh information transferred into displacement data or normal map data if for a game engine. The modeling stage consists of shaping individual objects that are later used in the scene. There are a number of modeling techniques, including: * Constructive solid geometry * Implicit surfaces *
Subdivision surface In the field of 3D computer graphics, a subdivision surface (commonly shortened to SubD surface) is a curved surface represented by the specification of a coarser polygon mesh and produced by a recursive algorithmic method. The curved surface, ...
s Modeling can be performed by means of a dedicated program (e.g., Blender,
Cinema 4D Cinema 4D is a 3D software suite developed by the German company Maxon. Overview As of R21, only one version of Cinema 4D is available. It replaces all previous variants, including BodyPaint 3D, and includes all features of the past 'Studio' ...
, LightWave, Maya, Modo,
3ds Max Autodesk 3ds Max, formerly 3D Studio and 3D Studio Max, is a professional 3D computer graphics program for making 3D animations, models, games and images. It is developed and produced by Autodesk Media and Entertainment. It has modeling capab ...
) or an application component (Shaper, Lofter in 3ds Max) or some scene description language (as in POV-Ray). In some cases, there is no strict distinction between these phases; in such cases modeling is just part of the scene creation process (this is the case, for example, with Caligari trueSpace and
Realsoft 3D Realsoft 3D is a modeling and raytracing application created by Realsoft Graphics Oy. Originally called Real 3D, it was developed for the Amiga computer and later also for Linux, Irix, Mac OS X, and Microsoft Windows. It was initially written in ...
). 3D models can also be created using the technique of Photogrammetry with dedicated programs such as
RealityCapture RealityCapture (RC) is photogrammetry software for creating 3D models out of unordered photographs (terrestrial and/or aerial) or laser scans without seams. The most common fields of its current use are cultural heritage (art and architecture), ...
, Metashape and 3DF Zephyr. Cleanup and further processing can be performed with applications such as MeshLab, the
GigaMesh Software Framework The GigaMesh Software Framework is a free and open-source software for display, editing and visualization of 3D-data typically acquired with structured light or structure from motion. It provides numerous functions for analysis of archaeologic ...
, netfabb or MeshMixer. Photogrammetry creates models using algorithms to interpret the shape and texture of real-world objects and environments based on photographs taken from many angles of the subject. Complex materials such as blowing sand, clouds, and liquid sprays are modeled with particle systems, and are a mass of 3D coordinates which have either
points Point or points may refer to: Places * Point, Lewis, a peninsula in the Outer Hebrides, Scotland * Point, Texas, a city in Rains County, Texas, United States * Point, the NE tip and a ferry terminal of Lismore, Inner Hebrides, Scotland * Points ...
,
polygon In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed '' polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the two ...
s, texture splats, or sprites assigned to them.


Human models

The first widely available commercial application of human virtual models appeared in 1998 on the Lands' End web site. The human virtual models were created by the company My Virtual Mode Inc. and enabled users to create a model of themselves and try on 3D clothing. There are several modern programs that allow for the creation of virtual human models ( Poser being one example).


3D clothing

The development of cloth simulation software such as Marvelous Designer, CLO3D and Optitex, has enabled artists and fashion designers to model dynamic 3D clothing on the computer. Dynamic 3D clothing is used for virtual fashion catalogs, as well as for dressing 3D characters for video games, 3D animation movies, for digital doubles in movies as well as for making clothes for avatars in virtual worlds such as SecondLife.


Comparison with 2D methods

3D photorealistic effects are often achieved without wire-frame modeling and are sometimes indistinguishable in the final form. Some graphic art software includes filters that can be applied to 2D vector graphics or 2D raster graphics on transparent layers. Advantages of wireframe 3D modeling over exclusively 2D methods include: * ''Flexibility,'' ability to change angles or animate images with quicker rendering of the changes; * ''Ease of rendering,'' automatic calculation and rendering photorealistic effects rather than mentally visualizing or estimating; * ''Accurate photorealism,'' less chance of human error in misplacing, overdoing, or forgetting to include a visual effect. Disadvantages compare to 2D photorealistic rendering may include a software learning curve and difficulty achieving certain photorealistic effects. Some photorealistic effects may be achieved with special rendering filters included in the 3D modeling software. For the best of both worlds, some artists use a combination of 3D modeling followed by editing the 2D computer-rendered images from the 3D model.


3D model market

A large market for 3D models (as well as 3D-related content, such as textures, scripts, etc.) still exists – either for individual models or large collections. Several online marketplaces for 3D content allow individual artists to sell content that they have created, including TurboSquid, CGStudio, CreativeMarket, MyMiniFactory,
Sketchfab Sketchfab is a 3D modeling platform website to publish, share, discover, buy and sell 3D, VR and AR content. It provides a viewer based on the WebGL and WebXR technologies that allows users to display 3D models on the web, to be viewed on ...
,
CGTrader CGTrader is a 3D model marketplace for VR/AR and CG projects, and professional 3D designer community. It was founded in 2011 and is headquartered in Vilnius, Lithuania. CGTrader has attracted funding from Practica Capital, a seed and venture fund b ...
and Cults. Often, the artists' goal is to get additional value out of assets they have previously created for projects. By doing so, artists can earn more money out of their old content, and companies can save money by buying pre-made models instead of paying an employee to create one from scratch. These marketplaces typically split the sale between themselves and the artist that created the asset, artists get 40% to 95% of the sales according to the marketplace. In most cases, the artist retains ownership of the 3d model while the customer only buys the right to use and present the model. Some artists sell their products directly in its own stores offering their products at a lower price by not using intermediaries. Over the last several years numerous marketplaces specializing in 3D rendering and printing models have emerged. Some of the 3D printing marketplaces are a combination of models sharing sites, with or without a built in e-com capability. Some of those platforms also offer 3D printing services on demand, software for model rendering and dynamic viewing of items. 3D printing file sharing and model rendering platforms include
Shapeways Shapeways, Inc. is a global, 3D printing marketplace and service, publicly traded company. Users design and upload 3D printable files, and Shapeways prints the objects for them or others. Users can have objects printed in over 55 materials and f ...
,
Sketchfab Sketchfab is a 3D modeling platform website to publish, share, discover, buy and sell 3D, VR and AR content. It provides a viewer based on the WebGL and WebXR technologies that allows users to display 3D models on the web, to be viewed on ...
,
Pinshape Pinshape Inc. is an online 3D printing community and marketplace with headquarters in Vancouver, British Columbia, Canada. It allows designers to share and sell their 3D printable designs. People with 3D printers to print those designs on their o ...
, Thingiverse, TurboSquid,
CGTrader CGTrader is a 3D model marketplace for VR/AR and CG projects, and professional 3D designer community. It was founded in 2011 and is headquartered in Vilnius, Lithuania. CGTrader has attracted funding from Practica Capital, a seed and venture fund b ...
,
Threeding Threeding is an online 3D printing marketplace and community for trading and free exchange of files ready for 3D printing. The website gives sellers personal storefronts where they list their 3D-printable models and make them available for a glob ...
,
MyMiniFactory MyMiniFactory is a file distribution platform founded in 2013 and headquartered in London, United Kingdom. The online platform hosts digital creators with a primary focus on hobbyists with an interest in 3D printing. MyMiniFactory have partnere ...
, and
GrabCAD GrabCAD, Inc. is a Cambridge, Massachusetts-based startup that created a free cloud-based collaboration environment that helps engineering teams manage, view and share CAD files. History GrabCAD was founded in Estonia in 2009 by current CEO, ...
.


3D printing

The term 3D printing or three-dimensional printing is a form of additive manufacturing technology where a three-dimensional object is created from successive layers material. Objects can be created without the need for complex expensive molds or assembly with multiple parts. 3D printing allows ideas to be prototyped and tested without having to go through a production process. In recent years, there has been an upsurge in the number of companies offering personalized 3D printed models of objects that have been scanned, designed in CAD software, and then printed to the customer's requirements. 3D models can be purchased from online marketplaces and printed by individuals or companies using commercially available 3D printers, enabling the home-production of objects such as spare parts and even medical equipment—.


Uses

Today, 3D modeling is used in various industries like film, animation and gaming,
interior design Interior design is the art and science of enhancing the interior of a building to achieve a healthier and more aesthetically pleasing environment for the people using the space. An interior designer is someone who plans, researches, coordin ...
and
architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing buildings ...
. They are also used in the medical industry to create interactive representations of anatomy. The medical industry uses detailed models of organs; these may be created with multiple 2-D image slices from an MRI or CT scan. The movie industry uses them as characters and objects for animated and real-life motion pictures. The video game industry uses them as assets for computer and video games. The
science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence ...
sector uses them as highly detailed models of chemical compounds. The architecture industry uses them to demonstrate proposed buildings and landscapes in lieu of traditional, physical
architectural model An architectural model is a type of scale model made to study aspects of an architectural design or to communicate design intent. They can be made from a variety of materials such as paper, plaster, plastic, resin, wood, glass and metal. They ...
s. The archaeology community is now creating 3D models of cultural heritage for research and visualization. The engineering community utilizes them as designs of new devices, vehicles and structures as well as a host of other uses. In recent decades the earth science community has started to construct 3D geological models as a standard practice. 3D models can also be the basis for physical devices that are built with 3D printers or CNC machines. In terms of video game development, 3D modeling is one stage in a longer development process. Simply put, the source of the geometry for the shape of an object can be: # A designer, industrial engineer or artist using a 3D-CAD system # An existing object, reverse engineered or copied using a 3-D shape digitizer or scanner # Mathematical data stored in memory based on a numerical description or calculation of the object. A wide number of 3D software are also used in constructing digital representation of mechanical models or parts before they are actually manufactured. CAD- and CAM-related software is used in such fields, and with this software, not only can you construct the parts, but also assemble them, and observe their functionality. 3D modeling is also used in the field of industrial design, wherein products are 3D modeled before representing them to the clients. In media and event industries, 3D modeling is used in stage and set design. The OWL 2 translation of the
vocabulary A vocabulary is a set of familiar words within a person's language. A vocabulary, usually developed with age, serves as a useful and fundamental tool for communication and acquiring knowledge. Acquiring an extensive vocabulary is one of the ...
of X3D can be used to provide semantic descriptions for 3D models, which is suitable for indexing and retrieval of 3D models by features such as geometry, dimensions, material, texture, diffuse reflection, transmission spectra, transparency, reflectivity, opalescence, glazes, varnishes, and enamels (as opposed to unstructured textual descriptions or 2.5D virtual museums and exhibitions using Google Street View on Google Arts & Culture, for example). The RDF representation of 3D models can be used in reasoning, which enables intelligent 3D applications which, for example, can automatically compare two 3D models by volume.


Testing a 3D solid model

3D solid models can be tested in different ways depending on what is needed by using simulation, mechanism design, and analysis. If a motor is designed and assembled correctly (this can be done differently depending on what 3D modeling program is being used), using the mechanism tool the user should be able to tell if the motor or machine is assembled correctly by how it operates. Different design will need to be tested in different ways. For example; a pool pump would need a simulation ran of the water running through the pump to see how the water flows through the pump. These tests verify if a product is developed correctly or if it needs to be modified to meet its requirements.


See also

*
List of 3D modeling software Following is a list of notable 3D modeling software, computer programs used for developing a mathematical representation of any three-dimensional surface of objects, also called 3D modeling. See also * List of computer-aided design editors * L ...
* List of common 3D test models * List of file formats#3D graphics * 3D city model * 3D computer graphics software * 3D figure * 3D printing *
3D scanner 3D scanning is the process of analyzing a real-world object or environment to collect data on its shape and possibly its appearance (e.g. color). The collected data can then be used to construct digital 3D models. A 3D scanner can be based on m ...
* 3D scanning * Additive manufacturing file format * Building information modeling * Cloth modeling * Computer facial animation * Cornell box *
Digital geometry Digital geometry deals with discrete sets (usually discrete point sets) considered to be digitized models or images of objects of the 2D or 3D Euclidean space. Simply put, digitizing is replacing an object by a discrete set of its points. Th ...
* Edge loop * Geological modeling * Holography *
Industrial CT scanning Industrial computed tomography (CT) scanning is any computer-aided tomographic process, usually X-ray computed tomography, that uses irradiation to produce three-dimensional internal and external representations of a scanned object. Industrial ...
* Marching cubes *
Open CASCADE Open Cascade is an Information Technology Company of Capgemini,. Open Cascade provides services in the domain of scientific and technical computing and simulation tools. Open Cascade is primarily known to public for its Open Source platforms the ...
* Polygon mesh * Polygonal modeling * Ray tracing (graphics) * Scaling (geometry) * SIGGRAPH * Stanford bunny * Triangle mesh * Utah teapot * Voxel * B-rep


References


External links

{{DEFAULTSORT:3d Modeling 3D computer graphics 3D imaging Visual effects Video game design Computer-aided engineering ja:3Dモデリング