Editing Volume rendering (section)

===Volume segmentation===
{{Anchor|Bone removal}}[[File:CT angiography of the head without and with bone removal.jpg|thumb|Volume segmentation include automatic bone removal, such as used in the right image in this [[Computed tomography angiography|CT angiography]].]]
[[File:3D CT of thorax.jpg|thumb|Volume segmentation of a 3D-rendered [[CT scan]] of the [[thorax]]: The anterior thoracic wall, the airways and the pulmonary vessels anterior to the root of the lung have been digitally removed in order to visualize thoracic contents: <br>- {{color|blue|blue}}: [[pulmonary arteries]] <br>- {{color|red|red}}: [[pulmonary veins]] (and also the [[abdominal wall]])<br>- {{color|yellow|yellow}}: the [[mediastinum]] <br>- {{color|violet|violet}}: the [[Thoracic diaphragm|diaphragm]] ]]
[[File:Visible-human-leonardo-1.jpg|thumb|Visualization of the inner organs from the segmented [[Visible Human Project|Visible Human]] data set rendered by [[Voxel-Man]], aside with a drawing of [[Leonardo da Vinci]] (1998)]]
[[Image segmentation]] is a manual or automatic procedure that can be used to section out large portions of the volume that one considers uninteresting before rendering, the amount of calculations that have to be made by ray casting or texture blending can be significantly reduced. This reduction can be as much as from O(n) to O(log n) for n sequentially indexed voxels. Volume segmentation also has significant performance benefits for other [[ray tracing (graphics)|ray tracing]] algorithms. Volume segmentation can subsequently be used to highlight or expose<ref>Tiede U., Schiemann T., Hoehne K.:  ''High quality rendering of attributed volume data'' In Proceedings of [[IEEE]] Visualization (1998), pp.&nbsp;255-262.</ref> structures of interest.