Grafis 3D. What is 3D? 3D Image x, y, z Tell a story, more information 2D Image x, y Communicate something simple (ie. cheat)

GRAFIKA KOMPUTER

Grafis 3D

What is 3D? 3D Image

x, y, zTell a story, more information

2D Image x, yCommunicate something simple (ie. cheat)

3D Graphics 3 major steps

Virtual 3d world ○ (3D models, physics [mass, rigid body], animations,

lightings, etc).

Occlusion (what is shown on 2D screen). ○ Effects (distance, blur)○ Realism (movement, ragdoll)○ LOD / mipmap

Display (as realistic as possible)

Display (Rendering)Vertex, polygon on 2D

ScreenShapes (squares,

rectangles, circles and rhomboids, but most are triangles)

Smoothing (subdivide a triangle into several ones)

Display (Rendering)Viewer can only look at

the screen to get all information.

Real world (look and feel)

Surface Texture○ Color○ Texture (smooth,

bumped ?)○ Reflectance (How much

light does it reflect?)

Lighting Light sources

Ray tracingDifferent LS different effects (windows, desk

lamps, candles, ceiling lamps, etc).Shadow (blur, explained later).

PerspectiveZ-buffer (assigns to each polygon

a number based on how close an object containing the polygon is to the front of the scene.

16-bit z-buffer : -32768 to 32767

Lowest value – renderedOthers – occludedEnsures that we don’t see background items

appearing through the middle of characters in the foreground.

Depth of Field In real life far objects appear out of focus In 3D all objects are sharp Uses:

Reinforce illusion of depth Focus viewers’ attention on certain items or characters.

Anti Aliasing

Adding gradual shades of color to the pixels surrounding a line.

2x AA, 4x AA, 8xAA FSAA/SAA/MSAA Very heavy on CPU

Moving Graphics FPS

Movie = 24 fps (or picture per second)More for slomoBlur happens for fast moving objects (natural)3D images ≠ photographs, no blurCreate blur = 60 fps (game)Movie 6.5 min = 24 x 60 x 6.5 = 93603D Image 6.5 min = 60 x 60 x 6.5 = 23.400

Adding realism – BlurMotion blur – spatial anti-aliasingeg. Mouse trail. Copies of the moving object are left behind in its

wake, with the copies growing ever less distinct and intense as the object moves farther away.

Adding Realism – ReflectionReflection on an object’s surface must be blurDifferent blur for different material

Rendering Fluid Motion for Us Is Hard Work for the

Computer Lowest “high-resolution” = 1024 x 768 786.432 pixel 32 bits color = 25.165.824 60 fps = 1.509.949.440 bits of information /

second w/o color, shape, lighting, etc.

Graphic Boards Early Computers = graphic boards only translating

image processed by CPU into electrical impulses. Only part of CPU used, others = inputs, interrupts,

sound, etc. Because of everything the computer must do to make

modern 3-D games and multi-media presentations happen, it's easy for even the fastest modern processors to become overworked and unable to serve the various requirements of the software in real time. It's here that the graphics co-processor helps: it splits the work with the CPU so that the total multimedia experience can move at an acceptable speed.

Wireframe – 3D objects – texture, lighting, blur, etc – displayed.

Wireframe – 3D objects – Graphic Boards - texture, lighting, blur, etc – displayed.

Modern graphic boards, take over after wireframe. 3D Now (AMD) to add more realism. Modern Graphic features: clip High Realism Real Time Rendering: clip. Increasingly more interesting market segment.