Page 133 - DCAP504_Computer Graphics

Computer Graphics

8.4 Summary

• The three-dimensional representation of data is stored in the computer. It is used for calculation
and rendering purposes.
• The 3-D graphics and 2-D graphics rely on the same algorithms.
• A spline is mathematically described with a piecewise cubic polynomial function.

• A Bezier curve is one of the approaches to construct a curve. It is determined by defining a
polygon.
• The creation of 3-D graphics can be divided into content creation, scene layout and rendering.
• Spline is defined as a parametric curve that can be well-defined by control points. The control
points were adjusted by the user to regulate the shape of curve.
• A solid surface is obtained by merging infinite number of curves without allowing any gap
between any two curves.
• Polygon surface is also referred to as “standard graphics object.” A polygon surface is specified
with a set of vertex coordinates and associated attribute parameters.
• The polygon mesh representation is common in design and solid modeling applications.
• The Bezier surface is defined by a set of control points. A B–spline surface is obtained by the
Cartesian product resulting from the extension of B-spline curve.
• Images that are 3-D in nature require the implementation of polygon rendering. It consists of three
types of shading namely, flat shading, gouraud shading and interpolation shading.

• Transformations are used in mapping spaces along the graphics pipeline. The three major types of
transformations are translation, scaling and rotation.
• The other transformations are shear, reflection and composite.
• Clipping is the process of removing objects that are not visible from the scene.

• In 3-D viewing, a viewing volume is specified with projection methods in the world coordinates
and a view port on the display.
8.5 Keywords

Application Programming Interface (API): It is a particular set of rules and specifications that a
software program can follow to access and make use of the services and resources provided by another
particular software program that implements that API.
Cartesian Product: It is the product two number sets. Example, product of two points coordinates.

Modeling: It is the mathematical representation of any 3-D image.
Open GL: It is a cross platform API used to write applications that develop graphic images.
Perspective Projection: It is an approximate representation of an object seen through naked eye on a flat
surface.
Raster: It represents grid of pixels on a display medium or screen.

Rendering: It refers to the creation of an image from a model with the help of computer programs.
Texturing: It is the addition of extra details or color to a 3-D graphic.
Wire Frame Model: It is the visual representation of 3-D model.
World Coordinates: They are real coordinates of an object.

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