ISRO2014-34

Question

How much memory is required to implement $z$-buffer algorithm for a $512 \times 512 \times 24$ bit-plane image?

• A. $768$ KB
• B. $1$ MB
• C. $1.5$ MB
• D. $2$ MB

Comments

plz provide correct solution...

Answer 1

In Z-buffer algorithm 2 buffers are used:

1. Frame Buffer

2. Depth Buffer

Depth buffer is used to store depth values for (x, y) position, as surfaces are processed (0 ≤ depth ≤ 1).

The frame buffer is used to store the intensity value of color value at each position (x, y).

total space required= depth buffer + frame buffer space

=>512 * 512 * 24 + 512 * 512 * 24 = 6291456 + 6291456 bits.

=> 12582912 bits

=> 1572864 Bytes

=>1.5 MB

Comments

space required=  depth buffer + frame buffer space

                         = 512 x 512 x 24bit + 512 x 512 x 24bit

                         =  2⁹ x 2⁹ x 3 Bytes  + 2⁹ x 2⁹ x 3 Bytes 

                         =  3/4 x 2²⁰ Bytes   +  3/4 x 2²⁰ Bytes 

                         =0.75 MB + 0.75 MB  = 1.5 MB

                               

Answer 2

The Z-buffer is a technology used in almost all contemporary computers, laptops and mobile phones for performing 3D graphics, for example for computer games. The Z-buffer is implemented as hardware in the silicon ICs (integrated circuits) within these computers. The Z-buffer is also used (implemented as software as opposed to hardware) for producing computer-generated special effects for films.

Furthermore, Z-buffer data obtained from rendering a surface from a light's point-of-view permits the creation of shadows by the shadow mapping technique.

Comments

but ITS ANSWER IS 1.5 MB

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Haha

Answer 3

512 X 512 X 24= 6291456 bits.

in KB= 6291456/ 1024 x 8 = 768 KB.

Comments

But the right answer is 1.5 MB.

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Please provide correct answer with relevant expalnation

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Please provide correct answer with relevant expalnation