Backface elimination is a 3D modeling technique that reduces memory requirements by making one side of each polygon disappear. The user selects a direction to restrict and depending on the camera or player’s movement, some polygons may alternate between invisible and visible. This technique reduces the number of polygons needed to run 3D movies and games, making it easier to play on consumer-grade projectors or computers.
Backface elimination is a rendering technique used in three-dimensional (3D) modeling for movies and games to reduce memory requirements. When polygons are used, they point clockwise or counterclockwise and the user must select which direction they want to restrict. After selecting this option, the backface deletion will take effect and make the other side of each polygon disappear, as they are not needed. Depending on how the player moves in a 3D game or through a 3D program, polygons can alternate between invisible and visible. Overall fewer polygons will be needed, so the amount of memory and processing requirements for the movie or game will be much less.
Polygons in a 3D game or movie often have a certain direction and wrap, and for backface culling to work, the user must select a direction to constrain. For example, if clockwise polygons are limited, all clockwise polygons will become invisible. Direction is normally selected based on the player’s common location, where the camera is located, and how the overall scenario is constructed.
Depending on what the user chooses and how the camera or player moves, some or many of the polygons will disappear from the program. If polygons are still needed to render an object, the back will become invisible, but it won’t completely disappear from the program. For example, if the camera is looking at an object from the front, the front and sides will be needed to compose the image, but since the back is not visible, that corner will disappear.
In early 3D movies and games, the camera or player rarely saw the back of polygonal objects, so there was no need to rotate the viewing angle. More advanced 3D graphics often have an adjustment camera, so backface culling doesn’t just make the polygons invisible. Invisible polygons will rotate based on where the user is moving. For example, if someone moves from the front to the back of a 3D object, the polygons in the back will load as the user gets closer to the back.
The purpose of backface culling is to reduce the amount of polygons needed to run a 3D movie or game. Memory is often high for many 3D projects and this makes viewing and processing media more difficult. By reducing the number of polygons required, it becomes much easier to play movies and games in consumer-grade projectors or computers.
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