Bidirectional texture function

Bidirectional texture function (BTF) ^[1][2][3] is a 6-dimensional function depending on planar texture coordinates (x,y) as well as on view and illumination spherical angles. In practice this function is obtained as a set of several thousand color images of material sample taken during different camera and light positions.

The BTF is a representation of the appearance of texture as a function of viewing and illumination direction. It is an image-based representation, since the geometry of the surface is unknown and not measured. BTF is typically captured by imaging the surface at a sampling of the hemisphere of possible viewing and illumination directions. BTF measurements are collections of images. The term BTF was first introduced in ^[1][2] and similar terms have since been introduced including BSSRDF^[4] and SBRDF (spatial BRDF). SBRDF has a very similar definition to BTF, i.e. BTF is also a spatially varying BRDF.

To cope with a massive BTF data with high redundancy, many compression methods were proposed.^[3][5]

Application of the BTF is in photorealistic material rendering of objects in virtual reality systems and for visual scene analysis,^[6] e.g., recognition of complex real-world materials using bidirectional feature histograms or 3D textons.

Biomedical and biometric applications of the BTF include recognition of skin texture.^[7]

See also

• BSDF == BRDF + BTDF, a 4+1 dimensional function of the scattering distribution from a single point/pixel/vertex.
• Columbia Utrecht Reflectance and Texture Database
• BTF Database Bonn and Measurement Lab
• CVPR 2010 BTF Modeling Tutorial
• BTFbase - BTF compression based on a multi-level vector quantization (free BTF shader)
• UTIA BTF Database - a new source of publicly available bidirectional texture function measurements

References

1. Kristin J. Dana; Bram van Ginneken; Shree K. Nayar; Jan J. Koenderink (1999). "Reflectance and texture of real world surfaces". ACM Transactions on Graphics. 18 (1): 1–34. doi:10.1145/300776.300778. S2CID 622815.
2. Kristin J. Dana; Bram van Ginneken; Shree K. Nayar; Jan J. Koenderink (1996). "Reflectance and texture of real world surfaces". Columbia University Technical Report CUCS-048-96. {{cite web}}: Missing or empty |url= (help)
3. Jiří Filip; Michal Haindl (2009). "Bidirectional Texture Function Modeling: A State of the Art Survey". IEEE Transactions on Pattern Analysis and Machine Intelligence. 31 (11): 1921–1940. doi:10.1109/TPAMI.2008.246. PMID 19762922. S2CID 9283615.
4. Jensen, H.W.; Marschner, S.R.; Levoy, M.; Hanrahan, P. (2001). "A practical model for subsurface light transport". ACM SIGGRAPH. pp. 511–518. {{cite web}}: Missing or empty |url= (help)
5. Vlastimil Havran; Jiří Filip; Karol Myszkowski (2009). . Computer Graphics Forum. 29 (1): 175–190. Archived from the original on 2010-08-04.
6. Michal Haindl; Jiří Filip (2013). Visual Texture: Accurate Material Appearance Measurement, Representation and Modeling. Advances in Computer Vision and Pattern Recognition. Springer-Verlag London 2013. p. 285. ISBN 978-1-4471-4901-9.
7. Oana G. Cula; Kristin J. Dana; Frank P. Murphy; Babar K. Rao (2005). "Skin Texture Modeling". International Journal of Computer Vision: 97–119.