Unit 66 Understand theory and applications of 3D modelling

Understand theory and applications of 3D

What is a 3D model?

In 3D computer graphics, 3D modelling (or three-dimensional modelling) is the process of developing a mathematical representation of any three-dimensional surface of an object, either inanimate or living. 

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. 

What would you use 3D modelling for?
3D models are widely used anywhere in 3D graphics and CAD. Actually, their use predates the widespread use of 3D graphics on personal computers. Many computer games used pre-rendered images of 3D models as sprites before computers could render them in real-time.
3D models nowadays are used in a wide variety of fields. The medical industry uses detailed models of organs or any equipment that they are creating. Video game industries use them as assets for computer and video games. The science sector uses them as highly detailed models of chemical compounds. The architecture industries use them to demonstrate proposed buildings and landscapes in lieu of traditional, physical architectural models. The engineering community uses them much more as they create new devices such as engines to a new vehicle or structures. Engineers use 3D modelling to create most of their equipment and for that reason they depend on 3D models.
Artists have also been likely to be found using software to create 3D models as a way of designing their own style of art. Artists have moved on from Photoshop and are using 3D modelling as a way to make their art more realistic.
3D modelling is very likely to be used in most creative industries, and even those that you dont expect. This is due to the 3D model allowing a perspective on all sides and angles of the object.

Modelling Process:

Polygonal Modelling:
Points in 3D space, called vertices, are connected by line segments to form a polygon models, because they are flexible and because computers can render them so quickly. However, polygons are planar and can only approximate curved surfaces using many polygons.

Curve Modelling: 
Surfaces are defined by curves, which are influenced by weighted control points. The curve follows the points. Increasing the weight for a point will pull the curve closer to that point.

Digital Sculpting:
3D sculpting has become very popular in the few years it has been around. There are three types of digital sculpting Displacement, which is the most widely used among applications at this moment, uses a dense model (Often generated by subdivisions surfaces of a polygon control mesh) and stores new locations for the vertex positions through use of a 32-bit image map that stores the adjusted locations.
Volumetric, loosely based 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 is similar to voxel but 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 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.

Animation:
An example of a 3D Modelling software is "Maya" This offers a range of tools for you to create 3D objects. In Maya you are able to animate the chosen object to do what you like for example; a ball that bounces. This is created by using frames, in each frame is a time difference which you move the objects arms or legs depending on what you want the animation to act like. The bouncing ball would gradually go up and down in each frame so that when you play it, it will act in that way. Animations are used in many industries such as games, TV, film, education, etc. These rely on the object behaving in this way either to advertise what they have created or to make a clip. For example a movie may need special effects which could be created in a variety of ways. A 3D model of a helicopter could be used in a film to act like its been destroyed. I.e "World War Z" contained a Maya created helicopter which was used to act as if it got destroyed, this was created as it would be safer and would cost less money than an actual helicopter.
Animation can also be used to show people the function of the object for example, a design of a weapon (shooting/reloading etc.) people would like to see an example of the gun in action if the gun is completely been made by scratch (hasn't been created) such as an alien weapon.
Animations can also be used for trailers for games or movies. A video game such as "Call of Duty" uses animations to create its trailers, this is usually used to show off the new graphics in the game. Having people act out in a games trailer will usually not work well when the game is released, when popularity nowadays are involved.

Art:
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.
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 Printing:
3D printing is a form of addictive manufacturing technology where a three dimensional object is created by laying down or build from successive layers of material.
In recent years, there has been an upsurge in the number of companies offering personalised 3D printed models of objects that have been scanned, designed in CAD software, and then printed to the customers requirements. As previously mentioned, 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.



Game Designers require 3D models to make 3D games. An example is the circus that's in the image. The circus was created using Maya which was moved into Unreal. Without 3D models the game Designers will have nothing to use for the game.
3D models are used to create a range of objects such as house-hold items to environments.

Textures and Shading:

Texture Maping:
To create a surface that resembles real life you need to turn to texture mapping. This process is similar to adding decorative paper to a white box. In 3D, texture mapping is the process of adding graphics to a polygon object. These graphics to a polygon object. These graphics can be anything from photographs to original designs. Textures can help age your object, and give them more of an appeal and realism.
Shading: A shader describes the entire material on an object, how the light is reflected, how its absorbed. Shaders and textures are similar as they make the 3D model have detail, however a texture is something that gets connected to a shader to give the 3D object its particular look.

A 3D object has many sides and a computer doesn't know how to correctly put a 2D texture onto a 3D object. A UV map is basically the 3D model stretched out into a flat 2D image to help place the textures in the wanted place.

Polygon Count: (The less the Poly-count the better the quality of play)
The Polygon count is the number of faces on your object. The higher the polygon count the more the game needs to keep the quality which in results you in needing to use tools to make less polygon counts. Most 3D models will contain high polygon counts, that will need to be turned down so that the quality of the 3D model is better. Usually polygon counts can just be a waste of usage on the 3D model and usually the designer wont tell the difference in design.

Specularity is basically the textures reflection of the light source on the object and how it shines. This is to help the idea of what the object material is made from such as metal would be shiny, wood would be solid.

Industries that use 3D modelling:

1. Entertainment:
3D modelling is in the entertainment field. There's no big film or popular television shows that dont uses extensive amounts of 3D modelling. The entertainment field usually is focused on designing 3D models when special effects are involved. Usually a real image is used and then the 3D models are used to make the environment different in someway such as; a eroding bridge or road. Its also good to place in objects that wouldn't be seen in that country if it was wanted. It could also be used to remove objects for that same reason.


2. Gaming:
3D modelling is evident in this area of gaming. This is needed to make everything such as; the weapons, the characters and even the environment. If the Game is a 3D game there needs to be 3D modelling involved or that game would be empty.

3. Architecture:
People would use plans and blueprints into a drawing (usually realistic), that was essentially the first "picture" of the future. The computer allows them to add motion and depth, so that clients can "fly-by" that illustrates all angles of vision. That is used so that the client knows exactly what they're in for on their project. An example is a client wanting a house made by his imagination, the designer would then use 3D modelling software which would show them in and out on what the house looks like due to it allowing to show each angle.

4. Geology and science:
Geology and scientists can use 3D modelling to create models that simulate earthquakes and land-forms, such as ocean trenches, that let them see the effects of stresses. Additionally, they can simulate motion, like flight patterns including various factors that affect them.


5. Advertising and marketing:
3D modeling artists can help advertisers and marketers depict their products in the ideal state. This allows companies to create new products and prototypes at drastic savings. And if the product fails the company will be able to fix the problem by fixing the problem in 3D modelling software. Additionally, once they have developed the right rendering, they can use that to sell the item before they have to invest capital in production

Representation: Almost all 3D models can be categorised into two categories.

Solid: These models define the volume of an object they represent (like a rock). These are more realistic, but more difficult to build. Solid models are mostly used for non-visual simulations such as medical and engineering simulations, for CAD specialised visual application such as ray tracing and constructive solid geometry
Shell/Boundary: These models represent the surface, e.g. the boundary of the object, not its volume (like an infinitesimally thin eggshell). These are easier to work with than solid models. Almost all visuals models used in games and film are shell models, due to that you are able to see the different angles of the object without needing to rotate the image.

Mesh Construction:
Mesh Construction is the process of creating objects with polygon meshes; these polygons are different forms of elements. The elements are vertices, edges, polygons and surfaces.
Models are usually used through pre-made 3D shapes such as; Cubes, Pyramids, Cylinders and spheres.
These shapes are then formed to create other shapes and sizes for the object. Usually a cube will be used for a house or a building, while a sphere can simply be a football. The 3D software also allows the designers to use other tools that can allow you to make a 3D model without actually making the pre-made shapes.

Faces and Edges: 

When designing the object the faces and edges are considered. They can be either enlarged, get smaller or make multiple, This can determine what the shape looks like due to the shape being reformed. A face is a closed set of edges, in which a triangle face has three edges and a quad has four. A polygon is a set of faces, In systems that support multi-sided polygons and faces are equivalent.

Rendering: 
3D rendering is the 3D computer graphics process of automatically converting 3D wire frame models into 2D images with 3D photo-realistic effects or non-photo-realistic rendering on a computer.
A renderer may support only 3-sided faces, so polygons must be constructed of many of these; however, many renders either support quads and higher-sided polygons, or are able to triangulate polygons to triangles on the fly, making it unnecessary to store a mesh in a triangulated form. In addition, in certain applications like head modelling it is desirable to be able to create both 3 and 4 sided polygons

Previews:
When designing a shape different previews are available which can give different effects and help the designer such as; the light effect can show the effects of light on your shape, and a "Wireframe" vision allows you to see all angles of the object without needing to check all sides. These are some examples of what the 3D softwares can offer.