3D animations are computer generated 2D images that depict 3D scenes. 3D scenes are made of objects created from polygons; polygons are made up of three components. The Vertex, the Edge and the Face. Edges connect vertexes together and when 3 or more vertexes are connected together by edges a face is made. An object that has been created using polygons is often referred to as a mesh.
There are many different ways to use polygons to model objects; industry standard packages such as 3ds max and maya have many different tools to manipulate the polygons, vertices and edges of 3D objects.
Depending on if the object you are modelling will deform, there are various different industry standard practices and rules to adhere to when modelling. Triangles should be avoid in areas of objects that will deform, this is because they give bad rendering results and don’t reflect light very well, edges should also loop around areas of 3ds objects that will deform regularly such as the shoulder of a humanoid character as shown in image A. Without the properly topology and placement of loops the character would not be able to bend its arms and fingers or rotate its shoulder. Correct topology with proper loops is only really important in organic characters, hard surfaces that do not deform can have different types of topology modeled using different techniques.
Depending on if the object you are modelling will deform, there are various different industry standard practices and rules to adhere to when modelling. Triangles should be avoid in areas of objects that will deform, this is because they give bad rendering results and don’t reflect light very well, edges should also loop around areas of 3ds objects that will deform regularly such as the shoulder of a humanoid character as shown in image A. Without the properly topology and placement of loops the character would not be able to bend its arms and fingers or rotate its shoulder. Correct topology with proper loops is only really important in organic characters, hard surfaces that do not deform can have different types of topology modeled using different techniques.
Sculpting polygons is also another way of modelling objects in 3d space, packages like Zbrush and Mudbox use hundreds of thousands if not millions of polygons to simulate clay and allow artist to sculpt characters, objects, or anything they can think of just like a traditional sculptor would. Sculpting however makes very dense meshes with allot of polygons, this means they have to be retopologised. Retopology is when a lower polygon mesh is created over a high polygon mesh to reduce the over number of polygons in the model while retaining the shape and form of the object. It is important to reduce polygon counts and optimize meshes so that they use less memory and render faster in pre rendered or real time rendering engine.
Once an artist has modelled an object they may want to add texture to it, a texture in 3D terms usually means colour and detail information on a 3D object. Before texture can be successfully applied to a 3D object, a UVW map must be created. A UV map is a set of coordinates that tell a 2D image how to wrap around a 3D object, without them the texture will appear distorted and stretched or ma not even display on a 3d object at all. Normal maps can also be applied to 3D models with UVW maps, a normal map takes sculpted detail from a high polygon version of the same mesh and uses it to add surface detail that reacts to light on the low poly mesh. Image B shows a 3D model without normal maps applied; it looks very low detail and doesn’t light very well due to the low polygon count. Image C shows that having normal maps increases the detail and lighting quality of a mesh, this is another process that would not work without a UVW map.
Once an artist has modelled an object they may want to add texture to it, a texture in 3D terms usually means colour and detail information on a 3D object. Before texture can be successfully applied to a 3D object, a UVW map must be created. A UV map is a set of coordinates that tell a 2D image how to wrap around a 3D object, without them the texture will appear distorted and stretched or ma not even display on a 3d object at all. Normal maps can also be applied to 3D models with UVW maps, a normal map takes sculpted detail from a high polygon version of the same mesh and uses it to add surface detail that reacts to light on the low poly mesh. Image B shows a 3D model without normal maps applied; it looks very low detail and doesn’t light very well due to the low polygon count. Image C shows that having normal maps increases the detail and lighting quality of a mesh, this is another process that would not work without a UVW map.
Just like our eyes need light photons to see, polygons need light photons hitting them for them to be visible, without any light shining on a polygons surface they cannot be displayed. Polygons only have one side that can be hit by light and displayed, the other side cannot be displayed in an engine, the side that can be displayed on a polygon is the “normal” side.
Lights can be created in 3D scenes or real time environments that work very similarly to how lights work in the real world. There are many different light types as well, omni lights send rays of light (photons) out in a spherical radius and light and polygons that the rays touch, spotlights mimic real world spotlights and create a cone of light that creates circularly lit areas, directional lights can be manipulated to send light in particular direction. There are also daylight systems which simulate sunlight, these systems can be controlled by geographical location as well as the time of day to give accurate lighting information to any 3d scene.
Image D shows an omni light lighting up a3D scene, Image E shows the same scene being lit by a daylight system.
Lights can be created in 3D scenes or real time environments that work very similarly to how lights work in the real world. There are many different light types as well, omni lights send rays of light (photons) out in a spherical radius and light and polygons that the rays touch, spotlights mimic real world spotlights and create a cone of light that creates circularly lit areas, directional lights can be manipulated to send light in particular direction. There are also daylight systems which simulate sunlight, these systems can be controlled by geographical location as well as the time of day to give accurate lighting information to any 3d scene.
Image D shows an omni light lighting up a3D scene, Image E shows the same scene being lit by a daylight system.
Rendering a 3D scene in a 3D package like 3ds max or Maya is the process of creating a 2D representation of a 3D scene in an image or video format. 3D packages have different rendering engines that can be tweaked and altered with different settings to give desired results. Depending on which settings are used, rendering can give varying results in quality; turning up the render quality settings also usually results in rendering taking longer. To create videos from 3d scenes, the renderer has to render each frame of an animated timeline and then convert each of those frames into a video format or image sequence.
3D objects characters and environments can also be rendered in real time, games engines are the most common form of real time rendering and they allow any user to walk around a 3d environment made up polygons and even interact with it. One of the most well-known 3D real time rendering languages used is Microsoft’s Direct 3D or DirectX. DirectX is an application programming interface, it renders 3D and 2D objects and it interacts with a PC or games console’s graphics card or graphics processing unit (GPU) to produce an image of the 3D scene on the screen.
Another very common form of application programming interface that games engines use to display their images is OpenGL. Open GL is a cross platform application programming interface. Unlike the previously mentioned Direct 3D, OpenGL is open to be used by anyone without permission and is completely none profit.
The most common industry standard software packages are Autodesks 3Ds Max, and Maya. These two packages are the most common and most intricate packages available; they are professional pieces of software that are used on the biggest blockbuster movies and video games. Pixologics Zbrush is also just industry standard and just as popular but is used for creating high detailed models through digital sculpting. It is difficult in modern times to find a movie that has been released that has not used some form of computer generated imagery, and almost always the CGI seen in movies is created in the previously mentioned packages. Advertising is also a huge industry which relies heavily on the use of 3D software, we are now in an era where the automobiles on car advertisements are almost never the real car and are almost always an extremely detailed and well rendered 3D model.
Bibliography
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Franklin Curt How Stuff Works [Online] // How 3-D Graphics Work. - 2014. - 2nd June 2014. - http://computer.howstuffworks.com/3dgraphics.htm.