What’s an Octree?

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Octrees are digital tree structures used in 3D and polygonal creations, such as video games. Each internal node has either no children or eight children, holding color information for the RGB color profile. Empty inner cubes are used for collision information. The structure is memory efficient, with each child holding a small amount of data. The octree has parent and child nodes, with each parent including eight nodes or none. Empty cubes are important for collision information. The structure uses memory efficiently due to the small amount of color and texture information and unnecessary data that can be trimmed.

An octree is a digital tree structure used to create three-dimensional (3D) and polygonal creations, primarily for the gaming industry. In the octree structure, each internal node has either no children or eight children – nothing in between – and each child node is capable of holding color information for the red-blue-green (RGB) color profile. The whole structure starts as a cube and the empty inner cubes are used for collision information. This structure is very memory efficient because each child holds a relatively small amount of data, and the tree can be limited in size.

When a model is made for a video game, it needs to have texture and color information, and it needs to be able to collide with other models. One of the structures used in this area is the octopus. Sometimes called the October tree, this name indicates the importance of the number eight in this tree structure. Like make trees, the octree has parent and child nodes. Unlike other trees, there is little variety in the number of child nodes that can be created by the parent.

Each parent can include eight nodes or none. Both types of cube are important in creating a fully rendered model. The most intensive cubes are those with eight nodes. Each internal node includes color and texture information, so the model can have a complex look. For example, if the model is a tree, each of the internal nodes should include a brown color for the trunk and shading information to create a realistic texture.

While cubes with eight nodes are important to an octree, empty cubes are just as important. The entire structure begins as a large empty cube, which other smaller cubes can inhabit. This cube, along with other empty cubes, is mainly used for collision information. For example, if a model collides with this model, the empty cubes will tell the model that it cannot move forward, because it creates a collision.

Building a proper model with an octree is challenging and contains a lot of information, but the structure itself uses memory very efficiently. One reason for this is that, while there is a lot of coding, the information is just color and texture information and, therefore, quite small. Another reason is that the tree has several levels that contain unnecessary data, and if trimmed, the memory can be further reduced.




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