2. CS 111.01Chapter 11.5 – Computer GraphicsPage 145 Computer Graphics Recent advances in processor power, display technology, memory capacity, and rendering algorithms have made it possible to produce dazzling images using relatively inexpensive computers. Image from Ringling School of Art & Design

3. CS 111.01Chapter 11.5 – Computer GraphicsPage 146 Drawing Lines & Circles Pixel-based display technologies cause inherent problems when displaying circles or non-vertical/non-horizontal lines. Images from 1993 SIGGRAPH Educators’ Slide Set

4. CS 111.01Chapter 11.5 – Computer GraphicsPage 147 AntialiasingAntialiasing Complex scenes lose their integrity when using single-colored pixels. Images from 1993 SIGGRAPH Educators’ Slide Set Jagged Profiles Loss Of Detail Disintegrating Textures A common way to address this problem is with antialiasing algorithms, which combine the colors affecting a particular pixel into a “blended” color that will minimize these negative effects.

5. CS 111.01Chapter 11.5 – Computer GraphicsPage 148 3D Shading The easiest way to store information about most 3D objects is as a set of polygons. Unfortunately, smooth objects aren’t necessarily polyhedral, so the resulting image looks bad. The easiest way to store information about most 3D objects is as a set of polygons. Unfortunately, smooth objects aren’t necessarily polyhedral, so the resulting image looks bad. The common solution to this problem is to use a shading algorithm, which progressively blends the shading of adjacent polygons to smooth out the reflection of the virtual light across the surface.

6. CS 111.01Chapter 11.5 – Computer GraphicsPage 149 Lighting Effects In order to accurately model lighting effects, the shading algorithm must take into account the position of the graphical scene’s virtual light source and the rendered objects’ locations with respect to it. More sophisticated lighting models take into account radiosity, the fact that light reflects off the surface of some objects and, in turn, illuminates other objects.

7. CS 111.01Chapter 11.5 – Computer GraphicsPage 150 Ray Tracing While expensive, ray tracing produces great photorealistic effects. Images from University of Waterloo A ray is cast through each pixel “into” the scene, and the pixel is painted the color of the first object hit by the ray. Shadows can be calculated by casting a new ray from the point of intersection to the light source. Reflections are calculated by casting a new ray from the intersection point at the reflective angle from the viewer’s position.

8. CS 111.01Chapter 11.5 – Computer GraphicsPage 151 Texture Mapping To give a greater sense of realism to 3D graphical objects, texture mapping provides an inexpensive means of placing 2D “wallpaper” around the objects. Bump mapping can make the results even more visually striking, by adding a displacement factor across the surface of the objects, giving the illusion of 3D texture in the resulting lighting effects.

9. CS 111.01Chapter 11.5 – Computer GraphicsPage 152 Fractals & Particle Systems Some 3D objects don’t lend themselves to the polyhedral approach. Fractals use elaborate mathematical patterns from chaos theory, probability theory, and complex analysis to produce natural-looking visual effects. An alternative approach has the graphics program keep track of thousands of small “particles” that are set up to behave in a similar, though not identical, manner.

10. CS 111.01Chapter 11.5 – Computer GraphicsPage 153 Virtual Reality Recent advances in input and output devices have made it possible to become “immersed” in an interactive virtual environment. Head-mounted displays, haptic gloves, and body exoskeletons have been developed to react to the user’s actions, yielding the appropriate visual, audio, and tactile feedback.

11. CS 111.01Chapter 11.5 – Computer GraphicsPage 154 StereoscopyStereoscopy To give the viewer a sense of depth, it’s necessary to provide each eye with a slightly different perspective. By letting the left eye see the entire sunset, while the right eye’s view is obscured by the lamppost, the viewer’s brain is fooled into perceiving depth in the image. Head-mounted displays provide a separate viewing screen for each eye, while “shutter” glasses alternate blocking each eye in synchronization with displaying the correct perspective.

12. CS 111.01Chapter 11.5 – Computer GraphicsPage 155 CAVE Environments To facilitate the sharing of a virtual environment, a CAVE-like alternative to individualized VR paraphernalia has been developed. A 3D wand is used to virtually propel the user into the environment, thus preventing the user from walking into a wall. Shuttered eyewear gives the user the illusion of three dimensions.

13. CS 111.01Chapter 11.5 – Computer GraphicsPage 156 Future Display Technology: Two Extremes Virtual Retinal Displays Projecting images directly onto the retina, these devices can literally “immerse” the viewer in the virtual environment, without a cumbersome helmet or elaborate room projection systems. Virtual Retinal Displays Projecting images directly onto the retina, these devices can literally “immerse” the viewer in the virtual environment, without a cumbersome helmet or elaborate room projection systems. Augmented Reality Rather than rendering an entire artificial environment, these systems overlay specific virtual objects on a transparent display of reality. Augmented Reality Rather than rendering an entire artificial environment, these systems overlay specific virtual objects on a transparent display of reality.