Page 114 - DCAP504_Computer Graphics

Unit 8: 3-D in Computer Graphics

Rendering
Rendering is the process of creation of actual 2-D or 3-D images from the scenes prepared in screen
layout setup stage. For interactive media the rendering is taken at a rate of 20 to 120 frames (images) per
second. It is comparatively slower in the case of non-interactive media.

Following are some of the rendering systems that can be used as plug ins to various 3-
D applications:

1. V-Ray
2. Yaf Ray
3. Indigo renderer
4. Mental ray
5. Maxwell

They are usually included in 3-D software packages

8.1.1 Splines
Spline is defined as a parametric curve that can be well-defined by set of coordinate positions called
control points. A spline is a flexible strip and the term ‘spline’ is the term taken from engineering
drawing and it is used to draw smooth curves through a specified set of points on the plane. These
points are called control points and are adjusted by the user to regulate the shape of curve. The curve
passes through all the points and it connects all the control points, this is also called interpolation. But if
the polynomials require to be fitted to the path that does not pass through the points then the curve
approximates the set of control points. The figure 8.1 displays the interpolation and approximation
spline.
Figure 8.1 : Spline

Interpolation spline Approximation spline

Source:
http://wikihelp.autodesk.com/Product_Help/Autodesk_Inventor/Autodesk_Inventor_2011/103Parts/12322-
Dsketches/1247Splines
The 3-D splines are curves whose radius keep changing constantly and pass through a series of control
points. The spline points can be restricted in a partial or complete manner. These spline points can be
added to the existing geometry while drawing the curve or at a later stage. The endpoints of a spline are
square in shape and the control points are diamond shaped to give a clear understanding. The control
points are known as ducks or knots.

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