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Volume Rendered Images
Volume rendering provides a variety of viewing options for voxel-based images using a technique called ray tracing. A ray is a straight-line path through the object perpendicular to the display plane. Each pixel in the display has an associated ray. During ray tracing all voxels along the ray's path are inspected and a ray value assigned to the corresponding pixel. A common ray value is the maximum voxel value along the ray. Mango supports two other options; median and minimum ray value. The displayed brightness of the volume rendered image is proportional to ray values.
It would be helpful to dynamically change object orientation for viewing volume rendered objects as provided for surface viewing. However, volume rendering is much more computationally demanding than surface rendering, and without special hardware full motion dynamic control of object orientation is not practical. Alternatively, dynamic viewing is possible when the desired views are precalculated. In Mango, volume rendered views are precalculated for rotation about one of the three major 3-D axes. The volume rendered views can then be animated or dynamically rotated about the chosen axis to view the volume rendered object.