3 d display-methods
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The document discusses different 3D display methods including parallel projection, perspective projection, depth cueing, visible line identification, visible surface identification, surface rendering, and material properties and shadows. Parallel projection preserves proportions but not realistic views, while perspective projection produces realistic views but not proportions. Depth cueing and visible surface identification are used to determine which surfaces are visible from a given viewing position. Surface rendering applies lighting effects to obscure hidden surfaces. Material properties and shadows can further enhance realism.
3 d display-methods
- 2. WELCOME TO OUR PRESENTATION OUR PRESENTATION TOPIC IS ABOUT 3D Display Methods
- 3. 3D Display Methods In this section, we focus on a subgoals of realistic picture. This co- ordinate reference defines the position and orientation for the planeof the camera, as shown in next slide.This plane must be used to display a view of the object; its description has to transferred to thecamera reference co-ordinates and projected onto the selected display plane. Then we can displayobject in wire frame form or we can apply lighting and surface rendering techniques to shade thevisible surfaces
- 5. Parallel Projection • In parallel projection, z co-ordinate is discarded and parallel ,lines from each vertex onthe object are extended until they intersect the view plane. • We connect the projected vertices by line segments which correspond toconnections on the original object.As shown in next slide a parallel projection preserves relative proportions of objects butdoes not produce the realistic views
- 8. • The perspective projection, on the other hand, produces realistic views but does not preserverelative proportions. In perspective projection, the lines of projection are not parallel.
- 9. Depth Cueing • To create realistic image, the depth information is important so that we can easily identify, for a particular viewing direction, which is the front and which is the back of displayed objects. Thedepth of an object can be represented by the intensity of the image. The parts of the objectsclosest to the viewing position are displayed with the highest intensities and objects farther awayare displayed with decreasing intensities. This effect is known as `depth cueing'.
- 11. Visible Surface Identification • The visible surface identification can be done with visible surface algorithms. They establishvisibility pixel by pixel across the viewing plane or determine surfaces for object as a whole.Once the visible, surfaces are identified we can apply surface rendering techniques onthem to obscure the hidden surfaces
- 12. Surface Rendering • Surface rendering involves setting the surface intensity of objects according to the lightingconditions in the scene and according to assigned surface characteristics. The lighting conditionsspecify the intensity and positions of light sources and the general background illuminationrequired for a scene. On the other hand the surface characteristics of objects specify the degree of transparency and smoothness or roughness of the surface; usually the surface rendering methodsare combined with perspective and visible- surface identification to generate a high degree of realism in a displayed scene.
- 13. Material Properties & Shadows • Some materials are shiny and reflect light onlyin certain directions relative to the viewer and light source, like a mirror. • We can introduce realism by reproducing shadows cast by objects on one another. Shadowsenhance realism and provide additional depth cues.