• Generally used for CT, MR imaging and
Ultrasounds
• 2D image is rendered from a 3D set of data or array
• Mostly used in medical applications but is also used in:
– Car Part manufacturing
– Scientific rendering: chemistry, entomology, rtc.

• Early approaches really had some problems:
– Distance between sections created faulty rendering
– Branching sections caused distortion
• Researchers sought to eliminate this by
– Cuberille technique
– Marching Cubes
– Dividing Cubes

How many ways can you do it? (cont’d)
• After finding these methods had problems too researchers sought to find a way to directly render the data.
– Additive re-projection technique
– Source-attenuation re-projection technique
– Depth shading algorithms
– Radiation transport equations
– Low-albedo/single scattering approximations

• After seeing that Direct Volume Rendering was the way to go researchers found various ways to achieve it.
• Main idea is the volume rendering integral
• Evaluated based on a certain simplification

Direct Volume Rendering Techniques
• Volume ray casting
• Splatting
• Shear warping
• Texture mapping
• Combinations (combining techniques to achieve better results)

Direct Volume Rendering Techniques
(cont’d)
• Other miscellaneous:
– Gaze-directed volume rendering
– Level-of-detail volume rendering
– Non-photorealistic volume rendering
– Interactive translucent volume rendering

• Different from ray casting
• Derived from graphic rendering equation
• Begins just as with regular volume rendering
• Good, but slow
• Has been combined with the Shear warp to produce better resulting images

• Does just what it says……
• Uses pre-shaded scheme
• Projected as a fuzzy ball
• Its 2D screen projection is called a “splat”, or a
“footprint” splat vs VRC

• One of the fastest techniques
• Three steps:
– The “shear”
– The intermediate image
– The “warp”
• That “warp” might not be such a great idea after all……. (full-image is bettteeerrrr!!!)

• Another class of volume ray casting
• More complex with data handling and buffering
• More multiplications to achieve the interpolations needed

• Similar to full image order
• Applied to the surface of a shape or polygon
• Used with texture mapping hardware

• Gaze-directed volume rendering
– Allowed generation of images with varying resolution
• Interactive translucent volume rendering
– Rendered volumetric shadows as well as the appearance of translucency
• Non-photorealistic rendering using stippling
– Simulate stipple drawing

• Level of detail volume rendering
– Similar to texture mapping
• Examples: Translucency and stippling

Applications: Is there anything else other than medical ones?
• Computed Tomography (CT scans)
– Shaded image
– Un-shaded image
• Magnetic Resonance imaging (MRI)
– Better at tissue stuff……
• Navigation through someone’s colon
– Hopefull not mine……

Applications: Is there anything else other than medical ones?
• Ultrasounds 3D/4D
– Fetal examinations
– Puncture procedures
– Can be limited if there isn’t enough amniotic fluid