ABOUT Z-BUFFER ALGORITHM

2. 7
Z-BUFFER
• Z-BUFFER METHOD
• Z-BUFFER ALGO
• IMPORTANT POINTS
• Uses
• Advantages:
• Disadvantages:
• Disadvantages:
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3. Z-BUFFER METHOD
• Also known as depth-buffer method
• Proposed by Catmull in 1974
• Easy to implement
• Z-buffer is like frame buffer , contain depths
• Two buffers are used –
-Frame Buffer
-Depth Buffer

4. Z-BUFFER ALGO
• Initialize all d[I,j]=1.0(max depth),c[I,j]=background color
For(each polygon)
For(each pixel in polygon projection)
{
Find depth-z of polygon at (x,y) corresponding to pixel (I,j)
If z<d[I,j]
C[I,j]=color;
End
}

5. IMP POINTS
• Z buffer method does not require pre-sorting of
polygons.
• This method can be executed quickly even with
many polygons.
• This can be implemented in hardware to
overcome the speed problem.
• No object to object comparison is required.
• This method can be applied to non-polygonal
objects.
• Hardware implementation of this algorithm are
available in some graphics workstations.
• The z-value of a polygon can be calculated
incrementally.

6. Uses:
The Z-buffer is a technology used in almost all
contemporary computers, laptops, and mobile phones for
performing 3D computer graphics.
The primary use now is for video games, which require fast
and accurate processing of 3D scenes
The Z-buffer is implemented in hardware within consumer
graphics cards.
The Z-buffer is also used (implemented as software as
opposed to hardware) for producing computer-generated
special effects for films.

7. Advantages:
A. It is simple to use.
B. Any kind of opaque surface
can be handled/removed.
C. It displays complex surface
intersections easily.
D. No depth storing of
objects is needed and
hence computational
complexity is linear.

8. Disadvantages:
A. Storage requirements are higher.
B. Since depth storing is not done, a location
in the z-buffer may have to be changed
many times depending on the number of
surfaces representing the scene.
C. It is a time-consuming process as it
needs to scan and convert every
polygon.
D. The space involved is very large. At
least it requires X*Y size of the
buffers.

9. THANK YOU