n420 d379 multimedia project development fall 2000
Download
Skip this Video
Download Presentation
N420 / D379 Multimedia Project Development Fall 2000

Loading in 2 Seconds...

play fullscreen
1 / 8

MS PowerPoint - PowerPoint PPT Presentation


  • 1232 Views
  • Uploaded on

N420 / D379 Multimedia Project Development Fall 2000 Topic 4: 3D Geometric Graphics Dr. Jeffrey Huang, Assistant Professor The School of Informatics, New Media Program, IUPUI e-mail: [email protected] 3D Graphics 3D Computer Programs

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'MS PowerPoint' - emily


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
n420 d379 multimedia project development fall 2000

N420 / D379 Multimedia Project DevelopmentFall 2000

Topic 4:

3D Geometric Graphics

Dr. Jeffrey Huang, Assistant Professor

The School of Informatics, New Media Program, IUPUI

e-mail: [email protected]

3d graphics
3D Graphics
  • 3D Computer Programs
    • Rapidly create, view, and change 3D forms without using physical 3D materials
    • Easily construct abstract 3D spaces – building and combining objects
    • Experimenting different “material properties”
      • Reflectiveness, transparency, and texture
      • Controlling lighting effects
    • Creating 3D models and looking at them from any point of view
    • Frustration:
      • Difficult to work with 3D information on a 2D screen with 2D input device
      • Unfamililiar technical terms: Primitives, polygonal meshes, sweeping a profile, Gouraud shading, ray tracing ….
slide3

3D Concepts

  • Use all concepts and methods in 2D graphics
    • 2D geometry  2D shapes  continuous 2D geometric description  reaterized  raster-based screens and printers
    • 3D geometry 2D & 3D shapes  continuous 2D geometric description  reaterized  raster-based screens and printers
      • Challenges: added dimension and effects of lighting on object surfaces
  • Modeling
    • Create 3D objects (similar to 2D in digital design and layout program)
  • Rendering
    • Rasterize the models (more complex than in 2D)
      • Project 3D information onto a 2D plane for display
      • Calculate lighting effects on object surfaces (hardware acceleration)
modeling
Modeling
  • Modeling is coping with complexity (van Dam, 1994)
    • Creating the objects, concept, or phenomenon that presents the important features
    • However, only presenting some part of a scene (feeling, experience, salient features), while leaving other parts out
    • 3D geometric modeling
      • Need not be based on physical geometric forms
      • Can be Scientific Visualization (data exploration) – creation of images based on very large sets of data. Ex: Wind Flow, NASA, …
  • Depth
    • X - and y - axes on Cartesian coordinate system + z -axis
modeling cont
Modeling (cont.)
  • 3D geometric modeling
    • Create simple model elements
    • Assemble the elements into more complex objects
    • Arrange objects in a 3D scene
    • Choose materials
    • Set up lights
    • Choose view points and rendering model
  • Behavioral modeling
    • Model objects’ behaviors
    • Animate articulated characters, facial expression, realistic skin deformation. Ex: deformable model, particle system, …
  • Real 3D world accuracy
rendering
Rendering
  • Rendering
      • Rasterize the models
      • Project 3D onto 2D plane
      • Calculate lighting effects on object surface
  • Surface Properties
    • Complexity of color in 3D
      • Color picker is not quite helpful because 3D CG model almost never appears to be a single color
        • Gradients of color value
        • Reflection and shadow from surrounding objects and lights make color change
      • Surface normal
        • Outward-facing direction of the face
      • Vector
        • A line with direction (arrow)

normal

surface properties
Surface Properties
  • Surface reflection properties
    • Diffuse reflection
      • angle of the light shining on surface
      • Light bounces equally in all directions
    • Specular reflection
      • mirror-like reflection
      • highlights
      • Material dependent, view dependent
      • Light bounces off only at an angle equal and

opposite to that of the incoming light

      • Non-perfect reflector: specular highlight is evident over a small angle and loses its coherence
    • Combination of diffuse and specular reflection: Diffuse + Specular

Incoming light

Diffuse

Perfect specular

Imperfect specular

Diffuse + Specular

surface properties cont
Surface Properties (cont.)
  • Surface Transmission properties
    • Light is absorbed
    • Light is transmitted
      • Transparency: light is not reflected
      • Refracted light: when light passes through different media it is bent
    • Refraction index: water  1.3, air  1, diamond  2.4
  • Texture
    • 3D paint-type images applied to 3D objects
    • 3D painting
ad