Obtaining the Bidirectional Texture Reflectance of Human Skin by means of a Kaleidoscope Jude Radloff Research Project Presentation Supervised by Shaun Bangay and Adéle Lobb. Part of the Virtual Reality Special Interests Group (VRSIG). Computer Science Honours – Rhodes University 28 July 2004
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Obtaining the Bidirectional Texture Reflectance of Human Skin by means of a Kaleidoscope Jude Radloff Research Project Presentation Supervised by Shaun.
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Obtaining the Bidirectional Texture Reflectance of Human
Skin by means of a Kaleidoscope
Jude Radloff
Research Project Presentation
Supervised by Shaun Bangay and Adéle Lobb.
Part of the Virtual Reality Special Interests Group (VRSIG).
Computer Science Honours – Rhodes University28 July 2004
Today’s Presentation
• Objective• Background to reflectance measurement• Introduction to the Kaleidoscope technique• Investigation of various configurations –
simulated• Practical implementation• Next step in research process• Questions
Objective :Increased realism of simulated real-world surfaces.
Ultimately human skin, being a highly complex surface.Currently focusing on preparation.
Bidirectional Texture Function (BTF) describes how INCOMING light is REFLECTED OFF a
surface, and how this VARIES over the surface
BTF ( θi, Φi, θo, Φo, u, v )
NBlight’s interaction with a surface
Han and Perlin, 2003
Proposed a novel technique in measuring reflectance by means of a kaleidoscope
Kaleidoscope’s reflective properties allow a sample to be viewed from a variety of directions - without the need for mechanical movement.
Potentially:» More economical (time / finance)» More accurate, because of less calibration» Simpler» Easier to use
Kaleidoscope System Setup
Investigation of configurations- by simulation
Considerations :
• Field of View
• Levels of Reflection
• Number of Sides
• Angle of Taper
• Alternative Configurations– Non-tapered– Additional mirror(s) beneath sample
Taper causes interreflections, which results in a virtual sphere
In a non-tapered configuration, the
result is a tiled sample image
Experimental configuration:
Tapered cylinder – each level of
reflection containing a
single distorted image
Recent development :Physical implementation of selected configurations
based on our findings in the AFRIGRAPH paper
On display today :
• 3-sided non-tapered kaleidoscope
• 4-sided tapered kaleidoscope• 4-sided tapered kaleidoscope with
extended reflective base – this novel configuration is expected to result in an even richer BTF measurement
Next Step…
• Set up camera and projector as described in the Han and Perlin paper (2003).
• Build up BTF database of view-illumination pair digital images.