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.


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
Write short notes on Text generation.   OR Character Generation Techniques  Character Generation Techniques   Two different representations are used for storing computer fon

what is the working procedure of CRT with diagram

Advantages of the Boundary Representation (i) This format gives efficient picture generation and easy access to other geometric information. (ii) The changes produced by mos

List out the merits of Plasma panel display?  Merits  Refreshing is not needed Produce a very steady image free of Flicker Less bulky than a CRT. Demerits

Polygon Filling Algorithm - Raster Graphics and Clipping In several graphics displays, this becomes essential to differentiate between different regions by filling them along

Web Design and Editing To edit and make a website, the big three softwares are use: 1)   DreamWeaver (MacroMedia) 2)   Frontpage (MicroSoft) 3)   Go Live (Adobe) 4)

Interrupts - Event driven devices Interrupts: An option to polling is the interrupt feature. The device sends an interrupt signal to the processor while an event happens. T

Optical Character Recognition Software (OCR) Frequently, you will have printed matter and the other text to incorporate in your project although no electronic text file. Along

difference between vecgen algoritham and bresenham''s algori

What is character generation and explain it''s two method: 1> Bitmap method 2> outline method.