Grafis 3D

What is 3D?  3D Image x, y, z Tell a story, more information  2D Image x, y Communicate 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 Screen Shapes (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 tracing Different LS different effects (windows, desk lamps, candles, ceiling lamps, etc). Shadow (blur, explained later). Perspective Z-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 : to 32767

Lowest value – rendered Others – occluded Ensures 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 slomo Blur happens for fast moving objects (natural) 3D images ≠ photographs, no blur Create blur = 60 fps (game) Movie 6.5 min = 24 x 60 x 6.5 = D Image 6.5 min = 60 x 60 x 6.5 =

 Adding realism – Blur Motion blur – spatial anti-aliasing eg. 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 – Reflection Reflection on an object’s surface must be blur Different blur for different material

Rendering  Fluid Motion for Us Is Hard Work for the Computer  Lowest “high-resolution” = 1024 x 768  pixel  32 bits color =  60 fps = 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.