Scan-line method, Computer Graphics

In contrast to depth-buffer method, here we identify one surface at one time, scan-line method deals along with multiple surfaces. Since it processes each scan-line at one time, all polygons intersected from that scan-line are examined to find out that surfaces are visible. The visibility test includes the comparison of depths of all overlapping surfaces, to find out that one i.e. closer to the view plane. It is declared like a visible surface and the intensity values at the positions beside the scan- line are entered in the refresh-buffer, if it is determined.

Assumptions:

a)      Plane of projection is Z=0 plane.

b)      Orthographic parallel projection.

c)      Direction of projection as: d = (0,0, -1)

d)      Objects made up of polygon faces.                     

 Scan-line algorithm resolves the hidden-surface issue, one scan-line at one time, generally processing scan lines starting the bottom to the top of the display.

 The scan-line algorithm is a one-dimensional version of the Z-Buffer. We need two arrays, intensity [x] and depth [x] to hold values for a particular scan-line.

 

                                          1519_Scan-line method.png

This time at Q1and Q2 both polygons are active that called sharing

Compare the z-values at Q1 for both the planes (P1 and P2). Let z1(1),z1(2) be the z-value at Q1 ,consequent to P1and P2 polygon correspondingly.

As the same z2(1), z2(2) be the z-value at Q2, consequent to P1and P2 polygon correspondingly.

Case1: z1(1)< z1(2)                         

             z2(1) < z2(2)  

In this case Q1, Q2 is filled along with the color of P2.

Case2: z1(2) < z1(1)

             z2(2) < z2(1)  

In this case Q1, Q2 is filled along with the color of P2.

Case3: Intersection is taking place.

In this condition we have to return to pixel by pixel and find out which plane is closer. After that choose the color of pixel

 

 

Posted Date: 3/22/2013 8:44:18 AM | Location : United States







Related Discussions:- Scan-line method, Assignment Help, Ask Question on Scan-line method, Get Answer, Expert's Help, Scan-line method Discussions

Write discussion on Scan-line method
Your posts are moderated
Related Questions
a__________of a scene is apart of a scene by which relate one part of the scene with the other parts of the scene

what is zooming and panning in computer graph please explan??

Types of Bitmap Images Bitmap images can include any number of colours but we distinguish among four main categories as: 1)      Line-art: These are images that include

State whether the following statements are true or false. Give reasons/examples to justify your answer.  a)  Cavalier projection is a parallel projection. b)  Angles are not

PIXEL PAINT: The pixel paint file format permits a document to be opened in the pixel paint and pixel paint professional graphics application. Such format permits you to identify

Chemistry: Computer animation is a very helpful tool in chemistry. Several things in chemistry are too small to see, and handle or do experiments on like, molecules and atoms for

Steps for clip a line segment-PQ Initially, find all the points of intersections of the line segment PQ along with the edges of the polygonal window and describe them eith

Phong Specular Reflection Model or Specular Reflection This model of local illumination is frequently termed as the Phong specular reflection model. Here we discuss the matter

Write a C program to create a window of specified size and position and draw the following objects with dimensions of your choice, to fit within the window.   (a) A point  (b) A

What are the advantages of rendering by patch splitting?  i. It is fast-especially on workstations with a hardware polygon-rendering pipeline.  ii. Its speed can be varied b