Question

How much memory is required to implement z-buffer algorithm for a 512 × 512 × 24 bit-plane image
1. 768 KB
2. 1 MB
3. 1.5 MB
4. 2 MB

Answer 1

Correct Answer - Option 3 : 1.5 MB

Answer Option 3

Explanation: 

Z-buffer: 

• Z-buffer is generally used for hidden surface detection. It is also known as the Depth-buffer method.
• The time complexity is the number of pixels times the number of objects and the space complexity is two times the number of pixels because two arrays of pixels are required, one for the frame buffer and the other for the depth buffer.
• These two buffers are used to store depth values and intensity of color respectively.

CALCULATION:

Memory required = 2 × 512 × 512 × 24 = 2 × 2⁹ × 2⁹ × 8 × 3 bits

= 2 × 2 × 3 × 2²⁰ bits = 12 M bits = 1.5 MB

Since 1 M = 2²⁰  and 1 byte = 8 bits