Computer Graphics Visible Surface Detection – Learn about Computer Graphics in simple and easy terms starting from trends in Computer Graphics, Basics, Line Generation Algorithm, Circle Generation Algorithm, Polygon Filling Algorithm, viewing and Clipping, 2D Transformation, 3D Computer Graphics, 3D Transformation, Computer Graphics Curves, Computer Graphics Surfaces, Visible Surface Detection, Fractals, Computer Animation. Computer Graphics, Tutorial, beginners, Basics, Line Generation Algorithm, Circle Generation Algorithm, Polygon Filling Algorithm, viewing and Clipping, 2D Transformation, 3D Computer Graphics, 3D Transformation, Computer Graphics Curves, Computer Graphics Surfaces, Visible Surface Detection, Fractals, Computer Animation. When z buffer algorithm in computer graphics pdf view a picture containing non-transparent objects and surfaces, then we cannot see those objects from view which are behind from objects closer to eye. We must remove these hidden surfaces to get a realistic screen image.
The Object-space method is implemented in physical coordinate system and image-space method is implemented in screen coordinate system. When we want to display a 3D object on a 2D screen, we need to identify those parts of a screen that are visible from a chosen viewing position. This method is developed by Cutmull. It is an image-space approach. In this method each surface is processed separately one pixel position at a time across the surface. It is applied very efficiently on surfaces of polygon.
Surfaces can be processed in any order. The z-coordinates are usually normalized to the range . The 0 value for z-coordinate indicates back clipping pane and 1 value for z-coordinates indicates front clipping pane. It is easy to implement. It reduces the speed problem if implemented in hardware. It processes one object at a time. It is time consuming process.
It is an image-space method to identify visible surface. This method has a depth information for only single scan-line. In order to require one scan-line of depth values, we must group and process all polygons intersecting a given scan-line at the same time before processing the next scan-line. It contains coordinate endpoints of each line in the scene, the inverse slope of each line, and pointers into the polygon table to connect edges to surfaces.