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Kamlesh Lakhwani, Lovely Professional University Unit 11: Hidden Surfaces

Unit 11: Hidden Surfaces

CONTENTS
Objectives
Introduction
11.1 Z-Buffer
11.2 Binary Space Partitioning
11.3 Painter’s Algorithm

11.4 Warnock Algorithm
11.5 Ray Tracing vs. Rasterization
11.6 Determination
11.7 Removal
11.8 Summary
11.9 Keywords
11.10 Self Assessment

11.11 Review Questions
11.12 Further Readings

Objectives
After studying this unit, you will be able to:

• Discuss the different types of buffers - Z-Buffer, C-Buffer, S-Buffer
• Explain the concept of binary space partitioning
• Discuss Painter’s algorithm
• Provide overview about Warnock algorithm
• Comprehend Ray tracing vs. Rasterization

• Explain the concept of determination
• Define removal
Introduction
In a 3-dimensional (3-D) objects, only the front surfaces and edges are visible to the viewer. In other
words, the surfaces and edges which are at the rear end are not visible. Moreover, this can also be
observed in an overlapping 2-dimensional (2-D) object. These surfaces and edges which are not visible
to the viewer are known as hidden surfaces and hidden edges respectively. The viewing parameters
such as rear view, side view, top view and bottom view decide the visibility of an object. In case an
object hides the other object or a part of an object hides another part of the same object, you will find
that only the object in front is visible.
The most important question here is to determine which lines or surfaces of the objects should be
visible. This process is termed as hidden surfaces, hidden line elimination, or visible surface
determination. The hidden line or hidden surface algorithm determines the lines, edges, surfaces that
are visible or invisible to a viewer. These algorithms are classified into two categories. One category is
the one that deals with the object definitions directly and the other category is the one that deals with
the object definitions through projected images. These two algorithms are called object space and image
space methods respectively.

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