Z- buffer algorithm, Computer Graphics

Assignment Help:

Q. Describe the z- Buffer algorithm for hidden surface removal.

Ans. Z- buffer method: This method compares surface depths at each pixel position on the projection plane. The surface depth is measured from the view plane along the z- axis of a viewing system. When object description is converted to projection coordinates (x, y, z) each pixel position on the view plane is specified by x & y coordinate, and z value gives the depth information. Thus object depth can by comparing the z- values. The z- buffer algorithm is usually implemented in the normalized coordinates, so that z- values range from 0 at the back clipping plane to 1 at the front clipping plane. Z- Buffer Algorithm  1. Initialize the depth buffer and refresh buffer so that for all buffer position (x, y), depth (x, y) =0 refresh (x, y) = 1 background. 2. For each position on each polygon surface, compare depth values to previously started values in the depth buffer to determine visibility. (a) Calculate the depth z for each (x,y) position on the polygon. (b) If z> depth (x, y) then set depth (x, y) =z refresh (x, y) = Isuff (x, y) Where I background intensity and Isuff (x, y) is the projection intensity value for the surface at pixel position (x, y). After all surface have been processed, the depth buffer contains depth values for the visible surface and the refresh buffer contains the corresponding intensity values for those surface. In the figure, among three surface, surface S1 has the smallest depth at view position (x, y) and hence highest z value. So it is visible at that position. To calculate the z- value, the plane equation Ax + By + Cz + D = 0 is used where (x, y, z) is any point on the plane, and the coefficient A, B, C and D are contents describing the spatial properties of the plane.                                                     Only one subtraction is needed to calculate z (x + 1, y) given z (x, y), since the quotient A/C is constant and ^x = 1. A similar incremental calculation cam be performed to determine the first value of z on the next scan line, decrementing by B/C for each ^y. Drawback of z- buffer (i) It requires an additional buffer and hence the large memory. (ii) It is a time consuming process as it requires comparison for each pixel instead for the entire polygon. 

 

 


Related Discussions:- Z- buffer algorithm

Area subdivision method-obscures the continuing two surface, Assume here ar...

Assume here are three polygon surfaces P,Q, R along with vertices specified by as: P: P1(1,1,1), P2(4,5,2), P3(5,2,5) And as Q: Q1(2,2,0.5), Q2(3,3,1.75), Q3(6,1,0.5) R: R1(0.5,

What are the steps to mapping artwork to an object, Question 1: (a) How...

Question 1: (a) How can you select and manipulate individual objects in a group? (b) How do you resize an object? Explain how you determine the point from which the object r

Scan conversion, State the purpose of scan conversion , along with the side...

State the purpose of scan conversion , along with the side effects

Removing polygons hidden through a surrounding polygon, Removing Polygons H...

Removing Polygons Hidden through a Surrounding Polygon: The key to capable visibility calculation lies actually a polygon is not visible whether it is in back of a surrounding

What is meant by addressability, What is meant by Addressability? Ans. ...

What is meant by Addressability? Ans. Addressability is the number of individual dots per inch (d.p.i.) that can be formed. If the address of the current dot is (x, y) then the

Determine about the liquid crystal display, Determine about the Liquid Crys...

Determine about the Liquid Crystal Display LCDs are organic molecules, naturally in crystalline state, and they get liquified when excited by heat or E field. Crystalline state

Parameterized systems - computer animation, Parameterized Systems - Compute...

Parameterized Systems - Computer Animation Parameterized Systems is the systems which permit objects motion features to be given as part of the object descriptions. The adjus

Open Gl, Write a program in C/C++ using OpenGL to create (without using bui...

Write a program in C/C++ using OpenGL to create (without using built in function) a square by implementing shear algorithm along 1. X-axis, 2.Y-axis.

Types of animation systems - computer animation, Types of Animation Systems...

Types of Animation Systems - Computer Animation We have discussed above about the sequencing of animation is helpful in developing any animation. Such sequencing is more or le

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd