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Why are polygons used in 3D graphics?

Answer: As realistic as 3D graphics may appear, they are typically comprised of flat, multi-sided polygons. These polygons are placed together to create a three-dimensional mesh, which produces a 3D image. While most polygons are triangles (which have the fewest possible sides), they can also be rectangles, hexagons, or other shapes. Colors and textures can be mapped onto these polygons, giving the final image a realistic appearance.

Because polygons are flat surfaces, they can only estimate curved shapes, which many objects have. Therefore, smaller polygons can more accurately represent curved objects. Of course, using smaller polygons also means more polygons are required to create the object. So the more polygons a 3D model has, the more smooth and realistic it will look.

For example, imagine a 3D image of a round ball that is three inches in diameter. If the ball was made up of only 100 polygons, it would be easy to notice the flat surfaces, making the ball seem rather blocky. However, if 1,000 polygons were used, the shapes would be less noticeable, giving the ball a smoother look. If 100,000 polygons were used to create the surface of the ball, the ball might appear completely round. The same concept holds true for more complex models, such as three-dimensional characters and other objects.

Thanks to advances in graphics processing technology, today's video cards can render millions of polygons per second. This allows for several highly detailed 3D models to be displayed on the screen at one time. Therefore, if you want to play a 3D video game on your computer with highly realistic graphics, chances are you'll need a video card with a powerful GPU.

Published: April 2, 2009 — by Per Christensson

Answer from the PC Help Center