Computer Graphics
Computer graphics are visual objects created by computers and designed to be displayed either on a TV screen, movie screen, or computer. These images are created by a range of specialized software.
This story was created for the Google Expeditions project by Vida Systems, now available on Google Arts & Culture.
Talented artists can use computers to create fantastical worlds that look as real as the world outside our window. These scenes are shaped using imagination, a keen eye for detail, and a methodical step–by–step process.
History of Computer Graphics
Computer graphics technology has evolved remarkably quickly. Realistic 3–D models were possible only 30 years after the first graphic display was introduced. This is due to the rapid development of computer memory technology, processor speed, and graphic design software.
Right from the outset computer graphics has been based on mathematical models.
Spacewar!
One of the first computer games with graphics was produced in 1962. Called Spacewar!, it allowed 2 players to pilot rocket ships. The aim was to try and shoot the other player out of the sky.
Raster Graphics
Games like Space Invaders, which was released in 1978, used raster graphics. These graphics use pixels, or tiny squares of color, to make up an image. Another name for this type of graphics is bitmap graphics.
Tron
In movie theaters in 1982, Tron was the first film to use computer graphics extensively. It featured vector graphics. Vector images use thin lines and curves to make up the final image, as opposed to pixels.
Dinosaurs Alive
The movie Jurassic Park, released in 1993, brought 3–D imagery to the forefront when the technology was used to recreate an extinct world. To do this, 3–D objects were scanned and turned into computer data using linear algebraic formulas.
Moving to VR
As 3–D images become more realistic when displayed on a 2–D screen, artists are now trying to create appealing 3–D images within a 3–D environment. These images are then used in virtual reality systems found in gaming, medicine, and the military.
Creating a 3–D World
3–D images can be used to tell a story, imagine new worlds, or even travel back through time. With the help of historical data, artists can recreate an event that happened before cameras were invented to give students an idea about what life was like.
Using paintings, documents, and other evidence artists can build a gladiator battle in the middle of the Colosseum, for example.
Concepting
The first step in creating any 3–D image is concepting. This is thinking about what you would like the final image to look like. There is no set way to do this; some artists sketch with stick figures while others make a detailed plan.
Research
Once the initial idea is drafted, lots of research is performed to determine all of the details needed. Primary sources are used when possible to work out items such as clothing style, building materials, and even hairstyles.
Places
Each part of the scene is carefully planned in advance. The artist decides what characters will be shown, the poses of the characters, the visual composition of the entire scene, the color palette, and the lighting.
Story
As well as looking realistic and visually interesting, the artist needs to make sure that the scene tells a story. By showing the gladiators in the middle of a battle, the viewer can start to imagine how scary and chaotic it would have been.
Modeling
After concepting, or planning what a 3–D image will look like, the next step in creating a 3–D scene is to start modeling. Specialized software uses mathematical modeling to create 3–D objects. Each object, or asset, within the scene needs to be modeled separately.
Vertices
Just like drawing a three–dimensional object by hand, computers use various geometric points called vertices, the points where 2 or more lines meet. By connecting polygons together on these vertices, the computer program creates the three–dimensional object.
Polygons
Each object in a 3–D scene is made up of polygons, which are two-dimensional shapes formed with lines, such as triangles and hexagons. The artist will create his or her 3–D image using this mesh first to ensure a realistic three–dimensional shape.
Shapes
Polygon meshes use different shapes to achieve different results. The mesh may include triangles, polygons, and types of quadrilaterals. Using a mix of shapes can create a more realistic 3–D representation and give the artist more scope.
Texturing and Shading
After enveloping a 3–D scene in polygon mesh, the next step is to texture and shade each object. This will give the objects color and allow the viewer to see what kind of material makes up each object.
Every object in the scene needs to be textured and shaded separately.
Texturing
Texturing is exactly like hand painting an object. The artist will color the object as realistically as possible. This can be very detailed work, however there are some software programs that can help speed the process along.
Shading
Shading is about telling the computer graphics software what material the object is made out of. A red rock looks very different from a red cloth, so it is important that the software can shade these colors differently.
Reflections
Shading an object also takes into account how light appears when shone on objects made up of different materials. For example, light will reflect differently off of water or metal than off of a piece of wood.
Diffusion
When shading, artists also need to consider how rough or smooth a surface is. This makes a difference in how light is diffused. Material diffuses light evenly, scattering light particles across the object. Shiny metal objects reflect light mainly in 1 direction.
Ray Tracing and Light
One of the essential parts of creating a three–dimensional object that will be viewed on a two–dimensional screen is to get the lighting exactly right.
The way light hits objects and either reflects, refracts, or diffuses goes unnoticed by the majority of people but 3–D artists need to have a great understanding of how light travels and how it works.
Light Source
The artist needs to decide where the main light source needs to be located. In this scene the sun is directly in the viewer's eyes, helping the viewer feel like they are in the Colosseum on a hot day, adding to the drama.
Complex Light
In an outdoor scene like this one, it is important to remember that the sun is not like a torch in a dark room. The sky itself emits light while various objects will be reflecting and adding light, creating a rich and complex picture.
HDR Lighting
This scene is lit using high dynamic range lighting. High dynamic range is a photography technique that retains a lot of lighting information, and this can help bring realistic lighting and reflections to a 3–D scene.
Clay Render
At this stage the lighting artist might make the materials on all the surfaces look like clay. Doing this can help the artist see how light is distributed without being distracted by other details present in the scene.
Rendering
The final step in the process of creating a dynamic, three–dimensional scene is called rendering. Rendering calculates the shading of the scene using a process called ray tracing. Once rendered, the entire scene looks smoother and more realistic, ready to be viewed.
Ray Tracing
This complex mathematical process calculates where millions of light particles would land and how they would behave. As the name suggests, ray tracing traces the light from the eye to its point of origin. It adds the final lighting layer to the image.
Rendering
Rendering is very similar to taking a photograph of the scene. Once all of the elements and objects are in their correct places and the lighting is correct, the computer graphics software is directed to smooth the image.
Time
The computer renders a scene like this in 6 to 8 hours. Rendering calculates every path the light takes to reach each pixel. A standard sized image composed of several million pixels may need thousands of rays to calculate accurately, so it's very heavy to compute!
