3.1 - Describing Virtual Worlds¶
From Chapter 1:
The field of computer graphics
uses computational devices to create images from geometric descriptions of 3D objects or from algorithmically created data.
This chapter explains the modeling required to create a 3D virtual world.
The description of a 3D computer graphics scene is virtual because it does not actually exist. A virtual world is composed of a group of 3D objects, a virtual camera, and virtual light sources. 3D objects are modeled by describing their:
- location – where is an object in reference to the entire scene?
- orientation – which way is the object turned or facing?
- volume – what 3-dimensional space does the object take up?
- surface properties – what color is the object? Is the object smooth or rough? Etc.
In addition to the objects in a virtual scene, we must describe a virtual camera which determines the location and direction of the scene’s view, and virtual light sources that illuminate the objects in the scene.
The description of a virtual world must be in mathematical values, symbols and operations that a computer is capable of manipulating. This means you need to understand some basic math! To make the math understandable it will be introduced slowly in 2-dimensional (2D) space and then extended into 3-dimensional (3D) space.
Glossary¶
- virtual
- Something that does not physically exist but is created by software to appear real. A virtual world is a simulated, artificial, imitation of the real world – or a make-believe world that exists only in your mind.
- object
- A single entity in a virtual world that has a location, takes up some volume of space, and can be moved, scaled, and rotated.
- model
- A mathematical description of an object.
- scene
- A collection of objects that make up a virtual world. A scene contains objects that we want to visualize.
- rendering
- The process of creating an image from a collection of virtual objects based on how virtual lights illuminate them and which objects are in the view of a virtual camera.
Self-Assessments¶
-
Q-61: What mathematical descriptions are needed to create a rendering of a 3D virtual world? (Select all that apply.)
- virtual objects
- Correct.
- virtual camera
- Correct.
- virtual lights
- Correct.
- virtual scene
- Incorrect. The word "scene" is a generic description of the contents of a rendering.
- virtual microphones
- Incorrect. 3D computer graphics could include sounds, but traditionally it does not.