RENDERING THE PHENOMENA OF VOLUME ABSORPTION IN HOMOGENEOUS TRANSPARENT MATERIALS
|
|
- Irene Strickland
- 6 years ago
- Views:
Transcription
1 RENDERING THE PHENOMENA OF VOLUME ABSORPTION IN HOMOGENEOUS TRANSPARENT MATERIALS YINLONG SUN, F. DAVID FRACCHIA, AND MARK S. DREW School of Computing Science, Simon Fraser University, Burnaby, BC, Canada V5A 1S6 {sun, fracchia, ABSTRACT Volume absorption is a crucial factor to the appearance of transparent objects such as colored glass and liquids. Due to the involvement of the spectral absorptivities of materials and path lengths of lights, volume absorption can generate interesting color variations. In this paper, we model volume absorption for homogeneous transparent materials using Bouguer-Lambertian law, and render its phenomena using a spectrum-based ray tracer. Our rendered images successfully display the subtle variations of colors due to volume absorption. We also compare our approach to an RGB-based one which assigns color tristimulus values for three monochromatic wavelengths, and show that the latter approach has significant errors and is thus inadequate for rendering volume absorption. This work expands the capability of rendering natural phenomena and can be used to improve the realism of computer generated imagery. Keywords: Volume absorption, natural phenomena, transparent materials, colors, ray tracing. 1 INTRODUCTION In realistic image synthesis we deal with two essential categories of objects: opaque and transparent (including translucent). Generally speaking, rendering transparent objects is much more complicated than opaque ones, as it involves not only all the factors for opaque objects such as illumination and surface properties, but also those specific to transparent objects such as particle scattering and volume absorption. Particle scattering (e.g., Rayleigh scattering) attenuates lights by redistributing them into all possible spatial directions related optical phenomena have been modeled and rendered [1,7,9,11]. Volume absorption also attenuates lights, but the attenuation does not modify the direction of light propagation within transparent materials. Although volume absorption is crucial to the appearance of transparent objects, to our knowledge no research has considered it to date. An important property of volume absorption is its dual characteristic: absorption depends not only on spectral absorptivities of materials, but also on the path lengths over which lights travel inside transparent objects. Due to this property, volume absorption can cause continuously varying but closely related colors across transparent objects. Because of the involvement of light paths, which depend on object boundaries as well as illumination directions, we cannot associate or describe transparent objects with fixed colors as we do for opaque ones. This implies that the common RGB-based approach does not suffice to render volume absorption and therefore we need to adopt an approach based on full spectral information [5,6,10,12,13]. In this paper, we apply a spectrum-based approach to modeling and rendering volume absorption in homogeneous transparent objects. Here homogeneous has two implications. First, transparent objects are clear and specular so that particle scattering is negligible. Second, refractive indices are uniform within transparent objects this ensures that lights still travel in straight lines inside the objects. Colored glass, gemstones, and liquid solutions (dye or chemical) are all examples of homogeneous transparent objects. The principle that governs volume absorption in homogeneous transparent materials is well known, viz., Bouguer-Lambertian law. Based on this law, the rendering of volume absorption can be easily carried out using ray tracing, as lengths of light paths inside transparent objects can be computed from the intersections between light rays and object boundaries, and these are readily available in any ray tracer. The resulting images successfully demonstrate the characteristics of volume absorption, including subtle variation of colors over transparent objects. We have also explored the possibility of rendering volume absorption with an RGB-based ray tracer by approximately associating color tristimulus values to three monochromatic wavelengths. However, the results have significant errors and prove inadequate in comparison to our spectrum-based approach. 2 PRINCIPLES OF VOLUME ABSORPTION Bouguer-Lambertian law [2,8,14] rigorously states that the internal transmittance for light traveling from one point to another inside a homogeneous transparent material is given by T internal a( λ) l ( λ) = 10, (1) where a(λ) is the spectral absorptivity of the material and l is the length of the light path. Note that internal transmittance applies only to one material and is therefore
2 Spectral absorptivity (1/m) Fig. 1: Examples of spectral absorptivities. Internal transmittance red glass light blue glass Wavelength (nm) Wavelegnth (nm) Fig. 2: Curves of internal transmittances for light path lengths of 1, 2, 4, 6, 8, 10 and 12 mm from top to bottom (cf. [8]). conceptually different from transmittance which applies to an interface of two materials or an entire transparent object [14]. Spectral absorptivity can be interpreted as the ratio between the absorbed and incident spectral power distributions (SPDs) of light over a unit propagation length, thus its dimension is inverse meters. Like spectral reflectance for opaque materials, spectral absorptivity is a characteristic of transparent materials; that is, it is independent of illumination and can be determined by experimental measurement. Fig. 1 shows two typical spectral absorptivity curves: the curve for light blue glass is fairly smooth, while the one for red glass has an abrupt change. This can cause significant difference in the appearance of objects made of light blue glass and red glass, as will be shown below. According to Bouguer-Lambertian law, internal transmittance, and thus the corresponding color, is very sensitive to the light path length l. In fact, increasing l not only decreases color intensity and deepens color saturation, but can also change the hue (the trace in color space as a function of l is not linear, as shown on pages in [2]). Qualitatively, these relationships can be seen from the curves in Fig. 2, which are the internal transmittances of light blue glass with l equal to 1, 2, 4, 6, 8, 10 and 12 mm from top to bottom (cf. [8]). For liquid solutions, it is important to also consider the dependence of the internal transmittance on liquid concentration. From Beer s law [2,8,14] we have T interal a ( λ) cl ( λ) = 10, (2) where c is concentration and a (λ) is the absorption per unit concentration per unit light path length. Note, however, that Beer s law is an approximation, especially at high concentrations. 3 ALGORITHMS It is straightforward to render light absorption phenomena with ray tracing, which requires only adding two new features to a regular ray tracer (cf. p. 780 in [3]). First, we should provide spectral absorptivities for all transparent objects so that the data can be conveniently retrieved when needed. (A simple implementation is to let every transparent object have a pointer pointing to the data of its spectral absorptivities.) Second, at the end of the computation for light shading (i.e., before returning the shade value), we should apply the attenuation according to Bouguer-Lambertian law. Fig. 3 displays pseudocode for a ray tracing function which is extended to handle volume absorption. This pseudocode is the same as a regular ray tracer except that a new code block has been added at the end of the function to handle the attenuation due to volume absorption. Note that the computation for attenuation (the last line of the new code block) should be applied to all components of SPDs. If we represent spectral functions by sampling, the computation becomes T a( λ ) l internal i = for all sampled wavelengths λ i. i ( λ ) = 10, i 1,..., N (3) As mentioned above, a color-based approach is not appropriate for rendering volume absorption because spectral absorptivities cannot be effectively described in terms of colors. If we do use an RGB-based ray tracer to render volume absorption, then the question is how to compute absorption attenuation for RGB triplets. A possible approach is that, for the red, green and blue components, we use the values of spectral absorptivity at the wavelengths corresponding to red, green and blue, respectively. For instance, we could use wavelengths nm, nm and nm, which are the values used in measuring the CIE color matching functions [14]. However, this approach will introduce significant errors because the three sampled values are strongly affected by the local peaks or valleys of spectral curves. Finally, we emphasize that the extension for volume absorption can be applied to any ray tracers. In other words, an extended ray tracer provides the new capability for volume absorption while retaining all the capabilities of the original one. For instance, if the original ray tracer handles Fresnel reflectance, the extended one does as well.
3 // Ray tracing shading function extended to include volume absorption attenuation SPD getshade( const Ray& incidray, // incident ray, input int depth // recursive trace depth, input ) { depth++; SPD lightshade = 0; // empty SPD bool hasintersection = getclosestintersection ( // function call incidray, // incident tracing ray, input interspoint, // the closest intersection point, to return surfnormal // surface normal direction, to return ); if (! hasintersection) { return lightshade; } compute contributions of reflection, refraction, light sources as in a regular ray tracer // detailed steps are ignored, refer to page 780 of Ref. [3] add the contributions to lightshade } // code block for absorption attenuation if (incidray is inside a transparent object) { // incidray has a pointer to the transparent object in which it propagates get spectralabsorptivity from the transparent object get raystartpoint from incidray; // raystartpoint is attribute of incidray double lightpathlength = distance between interspoint and raystartpoint lightshade *= exp(-spectralabsorptivity*lightpathlength); // attenuation } return lightshade; Fig. 3: Pseudocode for the ray tracing function extended with light absorption attenuation. 4 RESULTS AND DISCUSSION We present and discuss the full spectral results generated using an extended ray tracer as described in Fig. 3 (with consideration of Fresnel reflectance). The images in Fig. 4 demonstrate the typical phenomena associated with volume absorption. The objects in the two images are the same geometrically: each is a hexagonal pyramid (the bottom face is a regular hexagon), but the materials are red glass and light blue glass. The camera is directed toward the object from above and a white light source is located below the pyramid. Thus white lights from the light source transmit through the object and become colored due to selective volume absorption. For both objects in Fig. 4, the colors near the hexagonal edges appear less saturated (whiter) because the corresponding light paths within the glass are short and thus little light is absorbed. Considering the extreme case of zero path length, no light is absorbed and therefore the colors should be the same as those radiated from the light source. On the other hand, when approaching the axial center the colors appear more saturated and also lose intensity. This is because the All the images in this paper can be viewed at URL: corresponding light paths within the material are lengthened. Interestingly, the colors on the red object vary abruptly while on the blue one they vary smoothly. This is a consequence of the different shapes of the corresponding spectral absorptivities (see Fig. 1). Due to multiple internal reflections, transparent polygonal objects typically demonstrate colors with piecewise variations in intensity and saturation. This phenomenon is clearly seen in both the truncated cube of red glass and the brilliant cut diamond of light blue glass in Fig. 5. The images in Fig. 6 are used to compare the results generated using the full spectral approach (left column) and the RGB-triplets approach (right column). The images in the top row are bottles of red wine and the bottom row is white wine. The spectral absorptivities for the red and white wines are given in Fig. 7. We can see that the results from the RGB-based approach significantly differ from those of the spectrum-based approach, especially for the white wine case. The unreliable three-point sampling of spectral absorptivities is the source of error in the RGB approach. For the white wine, the values of the spectral absorptivity at the red and blue sampling wavelengths (700.0 nm and nm) are much larger than the average in their corresponding color regions, resulting in over-absorption of the red and blue
4 components and thus making the wine appear green. This example demonstrates the inadequacy of an RGB-based approach for rendering volume absorption. Spectral absorptivity (1/m) red wine Fig. 7: Spectral absorptivities of red and white wines. 5 FUTURE DIRECTIONS AND CONCLUSIONS In realistic image synthesis there has been increasing interest in full spectrum rendering, driven by the goals of achieving better accuracy [6,12,13], handling fluorescent illumination [10,12,13], and rendering spectrum-sensitive phenomena such as light interference [5] and fluorescence and phosphorescence [4]. This paper shows that volume absorption is another important reason for adopting a spectrum-based approach. As future research, our work can be extended to render liquid solutions with varying concentrations according to Beer s law. This is especially interesting in situations where the solution concentration changes with height (due to gravity), resulting in gradually varying colors. Furthermore, we can combine volume absorption with particle scattering or light dispersion to generate comprehensive phenomena associated with transparent objects. In conclusion, we have modeled volume absorption for homogeneous transparent materials based on Bouguer- Lambertian law and rendered the associated phenomena using a spectrum-based ray tracer. The rendered images successfully demonstrate the interesting and detailed characteristics of the phenomena. This work can be used to enhance rendering of natural phenomena and thus improve the realism of computer generated imagery. ACKNOWLEDGEMENTS white wine Wavelength (nm) We would like to thank Thomas Calvert, Alain Fournier, and John Dill for useful discussions. This research was supported by research and equipment grants from Natural Sciences and Engineering Research Council (NSERC), Canada. Thanks also to the Graphics and Multimedia Research Lab and the School of Computing Science at Simon Fraser University. REFERENCE [1] J. F. Blinn, Light Reflection Functions for Simulation of Clouds and Dusty Surfaces, Computer Graphics, Proc. of ACM SIGGRAPH 82, 1982, [2] R. M. Evans, An Introduction to Color (New York: John Wiley & Sons, 1961). [3] J. D. Foley et al., Computer Graphics Principles and Practice (Reading MA: Assison-Wesley, 1996). [4] A. S. Glassner, A Model of Fluorescence and Phosphorescence, Proc. of the Fifth Eurographics Workshop on Rendering, 1994, [5] J. S. Gondek et al., Wavelength Dependent Reflection Functions, Computer Graphics, Proc. of ACM SIGGRAPH 94, 1994, [6] R. A. Hall and D. P. Greenberg, A Testbed for Realistic Image Synthesis, IEEE Computer Graphics & Appl., 3(6), 1983, [7] P. Hanrahan and W. Krueger, Reflection from Layered Surfaces due to Subsurface Scattering, Computer Graphics, Proc. of SIGGRAPH 93, 1993, [8] D. L. MacAdam, Color Measurement Theme and Variations (Berlin: Springer-Verlag, 1985), [9] T. Nishita et al., Display of Clouds Taking into Account Multiple Anisotropic Scattering and Sky Light, Computer Graphics, Proc. of ACM SIGGRAPH 96, 1996, [10] M. S. Peercy, Linear Color Representations in Full Spectral Rendering, Computer Graphics, Proc. of SIGGRAPH 93, 1993, [11] H. Rushmeier and K. Torrance, The Zonal Method for Calculating Light Intensities in the Presence of a Participating Medium, Computer Graphics, Proc. of ACM SIGGRAPH 87, 1987, [12] Y. Sun, M. S. Drew, and F. D. Fracchia, Representing spectral functions by a composite model of smooth and spiky components for efficient full-spectrum photorealism, IEEE Workshop on Photometric Modeling for Computer Vision and Graphics, 1999, [13] Y. Sun, F. D. Fracchia, and M. S. Drew, A Composite Model for Representing Spectral Functions, Simon Fraser University, Technical Report SFU CMPT TR , This report can be found at ftp://fas.sfu.ca/pub/cs/tr/1998/ CMPT ps.gz. [14] G. Wyszecki and W. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulas (New York: Wiley, 1982).
5 Fig. 4: Continuous color variations generated by volume absorption. The objects in the two images are identical hexagonal pyramids, but the materials are red glass and light blue glass (see Fig. 1). The camera is directed toward the object from above and a white light source is located below the pyramid. White lights from the light source transmit through the object and become colored due to volume absorption. Fig. 5: A truncated cube of red glass (left) and a brilliant cut diamond of light blue glass (right) demonstrate colors with piecewise variations in both intensity and saturation due to the effect of volume absorption.
6 Fig. 6: Bottles of red (top row) and white (bottom row) wine rendered with the spectrum-based approach (left column) and the RGB-based approach (right column). The significant color differences demonstrate the inadequacy of the RGB-based approach for rendering volume absorption.
RENDERING LIGHT DISPERSION WITH A COMPOSITE SPECTRAL MODEL
RENDERING LIGHT DISPERSION WITH A COMPOSITE SPECTRAL MODEL Yinlong Sun, F. David Fracchia, and Mark S. Drew School of Computing Science, Simon Fraser University, Burnaby, BC, Canada V5A 1S6 {sun, fracchia,
More informationCh. 22 Properties of Light HW# 1, 5, 7, 9, 11, 15, 19, 22, 29, 37, 38
Ch. 22 Properties of Light HW# 1, 5, 7, 9, 11, 15, 19, 22, 29, 37, 38 Brief History of the Nature of Light Up until 19 th century, light was modeled as a stream of particles. Newton was a proponent of
More information4.5 Images Formed by the Refraction of Light
Figure 89: Practical structure of an optical fibre. Absorption in the glass tube leads to a gradual decrease in light intensity. For optical fibres, the glass used for the core has minimum absorption at
More informationLight. Electromagnetic wave with wave-like nature Refraction Interference Diffraction
Light Electromagnetic wave with wave-like nature Refraction Interference Diffraction Light Electromagnetic wave with wave-like nature Refraction Interference Diffraction Photons with particle-like nature
More informationPhysics-based Vision: an Introduction
Physics-based Vision: an Introduction Robby Tan ANU/NICTA (Vision Science, Technology and Applications) PhD from The University of Tokyo, 2004 1 What is Physics-based? An approach that is principally concerned
More informationVisual cues to 3D geometry. Light Reflection and Advanced Shading. Shading. Recognizing materials. size (perspective) occlusion shading
Visual cues to 3D geometry Light Reflection and Advanced Shading size (perspective) occlusion shading CS 4620 Lecture 17 1 2 Shading Recognizing materials Variation in observed color across an object strongly
More informationLecture 1 Image Formation.
Lecture 1 Image Formation peimt@bit.edu.cn 1 Part 3 Color 2 Color v The light coming out of sources or reflected from surfaces has more or less energy at different wavelengths v The visual system responds
More informationA spectrally based framework for realistic image synthesis
1 Introduction A spectrally based framework for realistic image synthesis Yinlong Sun 1, F. David Fracchia 2, Mark S. Drew 3, Thomas W. Calvert 4 1 Department of Computer Sciences, Purdue University, 1398
More informationLocal Illumination. CMPT 361 Introduction to Computer Graphics Torsten Möller. Machiraju/Zhang/Möller
Local Illumination CMPT 361 Introduction to Computer Graphics Torsten Möller Graphics Pipeline Hardware Modelling Transform Visibility Illumination + Shading Perception, Interaction Color Texture/ Realism
More informationCS 348B Project Report Mingyu Gao, Jing Pu
CS 348B Project Report Mingyu Gao, Jing Pu mgao12@stanford.edu, jingpu@stanford.edu Introduction In this project, we plan to render silicon wafers with the signature of rainbow colors on the reflecting
More informationSynthesis of Facial Images with Foundation Make-Up
Synthesis of Facial Images with Foundation Make-Up Motonori Doi 1,RieOhtsuki 2,RieHikima 2, Osamu Tanno 2, and Shoji Tominaga 3 1 Osaka Electro-Communication University, Osaka, Japan 2 Kanebo COSMETICS
More informationLecture 4: Reflection Models
Lecture 4: Reflection Models CS 660, Spring 009 Kavita Bala Computer Science Cornell University Outline Light sources Light source characteristics Types of sources Light reflection Physics-based models
More informationA Survey of Modelling and Rendering of the Earth s Atmosphere
Spring Conference on Computer Graphics 00 A Survey of Modelling and Rendering of the Earth s Atmosphere Jaroslav Sloup Department of Computer Science and Engineering Czech Technical University in Prague
More informationRepresenting and Computing Polarized Light in a Ray Tracer
Representing and Computing Polarized Light in a Ray Tracer A Technical Report in STS 4600 Presented to the Faculty of the School of Engineering and Applied Science University of Virginia in Partial Fulfillment
More informationCS 5625 Lec 2: Shading Models
CS 5625 Lec 2: Shading Models Kavita Bala Spring 2013 Shading Models Chapter 7 Next few weeks Textures Graphics Pipeline Light Emission To compute images What are the light sources? Light Propagation Fog/Clear?
More informationLecture 7 Notes: 07 / 11. Reflection and refraction
Lecture 7 Notes: 07 / 11 Reflection and refraction When an electromagnetic wave, such as light, encounters the surface of a medium, some of it is reflected off the surface, while some crosses the boundary
More informationPhysics 202, Lecture 23
Physics 202, Lecture 23 Today s Topics Lights and Laws of Geometric Optics Nature of Light Reflection and Refraction Law of Reflection Law of Refraction Index of Reflection, Snell s Law Total Internal
More informationShading. Brian Curless CSE 557 Autumn 2017
Shading Brian Curless CSE 557 Autumn 2017 1 Reading Optional: Angel and Shreiner: chapter 5. Marschner and Shirley: chapter 10, chapter 17. Further reading: OpenGL red book, chapter 5. 2 Basic 3D graphics
More informationLECTURE 37: Ray model of light and Snell's law
Lectures Page 1 Select LEARNING OBJECTIVES: LECTURE 37: Ray model of light and Snell's law Understand when the ray model of light is applicable. Be able to apply Snell's Law of Refraction to any system.
More informationØ Sampling Theory" Ø Fourier Analysis Ø Anti-aliasing Ø Supersampling Strategies" Ø The Hall illumination model. Ø Original ray tracing paper
CS 431/636 Advanced Rendering Techniques Ø Dr. David Breen Ø Korman 105D Ø Wednesday 6PM 8:50PM Presentation 6 5/16/12 Questions from ast Time? Ø Sampling Theory" Ø Fourier Analysis Ø Anti-aliasing Ø Supersampling
More informationspecular diffuse reflection.
Lesson 8 Light and Optics The Nature of Light Properties of Light: Reflection Refraction Interference Diffraction Polarization Dispersion and Prisms Total Internal Reflection Huygens s Principle The Nature
More informationOutline Radiometry of Underwater Image Formation
Outline - Introduction - Features and Feature Matching - Geometry of Image Formation - Calibration - Structure from Motion - Dense Stereo - Radiometry of Underwater Image Formation - Conclusion 1 pool
More informationHot Sync. Materials Needed Today
Chapter 11 Lesson 2 Materials Needed Today Please take these materials out of your backpack. Pencil Blank sheet of paper for a lab! Hot Sync Thursday 3/27/14 After learning how light acts. Write a new
More informationReal-time Rendering of Soap Bubbles Taking into Account Light Interference
Real-time Rendering of Soap Bubbles Taking into Account Light Interference Kei Iwasaki Keichi Matsuzawa Tomoyuki Nishita The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan Phone: +81.3.5841.4096
More informationSimple Lighting/Illumination Models
Simple Lighting/Illumination Models Scene rendered using direct lighting only Photograph Scene rendered using a physically-based global illumination model with manual tuning of colors (Frederic Drago and
More informationCS354 Computer Graphics Ray Tracing. Qixing Huang Januray 24th 2017
CS354 Computer Graphics Ray Tracing Qixing Huang Januray 24th 2017 Graphics Pipeline Elements of rendering Object Light Material Camera Geometric optics Modern theories of light treat it as both a wave
More informationCENG 477 Introduction to Computer Graphics. Ray Tracing: Shading
CENG 477 Introduction to Computer Graphics Ray Tracing: Shading Last Week Until now we learned: How to create the primary rays from the given camera and image plane parameters How to intersect these rays
More information782 Schedule & Notes
782 Schedule & Notes Tentative schedule - subject to change at a moment s notice. This is only a guide and not meant to be a strict schedule of how fast the material will be taught. The order of material
More informationw Foley, Section16.1 Reading
Shading w Foley, Section16.1 Reading Introduction So far, we ve talked exclusively about geometry. w What is the shape of an object? w How do I place it in a virtual 3D space? w How do I know which pixels
More informationC101-E137 TALK LETTER. Vol. 14
C101-E137 TALK LETTER Vol. 14 Diffuse Reflectance Measurement of Powder Samples and Kubelka-Munk Transformation ------- 02 Application: Measuring Food Color ------- 08 Q&A: What effect does the scan speed
More informationRules for Deviation of Light Rays During Refraction
REFLECTION OF LIGHT Refraction of light is the phenomenon due to which a ray of light deviates from its path, at the surface of separation of two media, when the ray of light is travelling from one optical
More informationDispersion (23.5) Neil Alberding (SFU Physics) Physics 121: Optics, Electricity & Magnetism Spring / 17
Neil Alberding (SFU Physics) Physics 121: Optics, Electricity & Magnetism Spring 2010 1 / 17 Dispersion (23.5) The speed of light in a material depends on its wavelength White light is a mixture of wavelengths
More informationLight: Geometric Optics
Light: Geometric Optics The Ray Model of Light Light very often travels in straight lines. We represent light using rays, which are straight lines emanating from an object. This is an idealization, but
More informationRecall: Basic Ray Tracer
1 Recall: Ray Tracing Generate an image by backwards tracing the path of light through pixels on an image plane Simulate the interaction of light with objects Recall: Basic Ray Tracer Trace a primary ray
More informationChapter 35. The Nature of Light and the Laws of Geometric Optics
Chapter 35 The Nature of Light and the Laws of Geometric Optics Introduction to Light Light is basic to almost all life on Earth. Light is a form of electromagnetic radiation. Light represents energy transfer
More informationThe Rendering Equation. Computer Graphics CMU /15-662
The Rendering Equation Computer Graphics CMU 15-462/15-662 Review: What is radiance? Radiance at point p in direction N is radiant energy ( #hits ) per unit time, per solid angle, per unit area perpendicular
More informationLecture 1. Computer Graphics and Systems. Tuesday, January 15, 13
Lecture 1 Computer Graphics and Systems What is Computer Graphics? Image Formation Sun Object Figure from Ed Angel,D.Shreiner: Interactive Computer Graphics, 6 th Ed., 2012 Addison Wesley Computer Graphics
More informationLight and Electromagnetic Waves. Honors Physics
Light and Electromagnetic Waves Honors Physics Electromagnetic Waves EM waves are a result of accelerated charges and disturbances in electric and magnetic fields (Radio wave example here) As electrons
More informationSpectral Estimation of Skin Color with Foundation Makeup
Spectral Estimation of Skin Color with Foundation Makeup M. Doi 1, R. Ohtsuki, and S. Tominaga 3 1 Department of Telecommunications and Computer Networks, Faculty of Information and Communication Engineering,
More informationChapter 32 Light: Reflection and Refraction. Copyright 2009 Pearson Education, Inc.
Chapter 32 Light: Reflection and Refraction Units of Chapter 32 The Ray Model of Light Reflection; Image Formation by a Plane Mirror Formation of Images by Spherical Mirrors Index of Refraction Refraction:
More informationEstimation of Reflection Properties of Silk Textile with Multi-band Camera
Estimation of Reflection Properties of Silk Textile with Multi-band Camera Kosuke MOCHIZUKI*, Norihiro TANAKA**, Hideaki MORIKAWA* *Graduate School of Shinshu University, 12st116a@shinshu-u.ac.jp ** Faculty
More informationIntroduction to color science
Introduction to color science Trichromacy Spectral matching functions CIE XYZ color system xy-chromaticity diagram Color gamut Color temperature Color balancing algorithms Digital Image Processing: Bernd
More informationLighting. Figure 10.1
We have learned to build three-dimensional graphical models and to display them. However, if you render one of our models, you might be disappointed to see images that look flat and thus fail to show the
More informationSESSION 5: INVESTIGATING LIGHT. Key Concepts. X-planation. Physical Sciences Grade In this session we:
SESSION 5: INVESTIGATING LIGHT Key Concepts In this session we: Explain what light is, where light comes from and why it is important Identify what happens when light strikes the surface of different objects
More information2/26/2016. Chapter 23 Ray Optics. Chapter 23 Preview. Chapter 23 Preview
Chapter 23 Ray Optics Chapter Goal: To understand and apply the ray model of light. Slide 23-2 Chapter 23 Preview Slide 23-3 Chapter 23 Preview Slide 23-4 1 Chapter 23 Preview Slide 23-5 Chapter 23 Preview
More informationLecture 14: Refraction
Lecture 14: Refraction We know from experience that there are several transparent substances through which light can travel air, water, and glass are three examples When light passes from one such medium
More informationLocal Reflection Models
Local Reflection Models Illumination Thus Far Simple Illumination Models Ambient + Diffuse + Attenuation + Specular Additions Texture, Shadows, Used in global algs! (Ray tracing) Problem: Different materials
More informationChapter 24. Geometric optics. Assignment No. 11, due April 27th before class: Problems 24.4, 24.11, 24.13, 24.15, 24.24
Chapter 24 Geometric optics Assignment No. 11, due April 27th before class: Problems 24.4, 24.11, 24.13, 24.15, 24.24 A Brief History of Light 1000 AD It was proposed that light consisted of tiny particles
More informationMethod of determining the optical properties of ceramics and ceramic pigments: measurement of the refractive index
Method of determining the optical properties of ceramics and ceramic pigments: measurement of the refractive index A. Tolosa (1), N. Alcón (1), F. Sanmiguel (2), O. Ruiz (2). (1) AIDO, Instituto tecnológico
More informationShading. Reading. Pinhole camera. Basic 3D graphics. Brian Curless CSE 557 Fall Required: Shirley, Chapter 10
Reading Required: Shirley, Chapter 10 Shading Brian Curless CSE 557 Fall 2014 1 2 Basic 3D graphics With affine matrices, we can now transform virtual 3D objects in their local coordinate systems into
More informationCOMPUTER GRAPHICS AND INTERACTION
DH2323 DGI17 COMPUTER GRAPHICS AND INTERACTION INTRODUCTION TO RAYTRACING Christopher Peters CST, KTH Royal Institute of Technology, Sweden chpeters@kth.se http://kth.academia.edu/christopheredwardpeters
More informationLighting. To do. Course Outline. This Lecture. Continue to work on ray programming assignment Start thinking about final project
To do Continue to work on ray programming assignment Start thinking about final project Lighting Course Outline 3D Graphics Pipeline Modeling (Creating 3D Geometry) Mesh; modeling; sampling; Interaction
More informationMACHINING SURFACE FINISH QUALITY USING 3D PROFILOMETRY
MACHINING SURFACE FINISH QUALITY USING 3D PROFILOMETRY Prepared by Duanjie Li, PhD Morgan, Ste1, Irvine CA 91 P: 99.1.99 F: 99.1.93 nanovea.com Today's standard for tomorrow's materials. 1 NANOVEA INTRODUCTION
More informationEffective Medium Theory, Rough Surfaces, and Moth s Eyes
Effective Medium Theory, Rough Surfaces, and Moth s Eyes R. Steven Turley, David Allred, Anthony Willey, Joseph Muhlestein, and Zephne Larsen Brigham Young University, Provo, Utah Abstract Optics in the
More informationVisual Appearance and Color. Gianpaolo Palma
Visual Appearance and Color Gianpaolo Palma LIGHT MATERIAL Visual Appearance Color due to the interaction between the lighting environment (intensity, position, ) and the properties of the object surface
More informationWavefronts and Rays. When light or other electromagnetic waves interact with systems much larger than the wavelength, it s a good approximation to
Chapter 33: Optics Wavefronts and Rays When light or other electromagnetic waves interact with systems much larger than the wavelength, it s a good approximation to Neglect the wave nature of light. Consider
More informationThe exam begins at 2:40pm and ends at 4:00pm. You must turn your exam in when time is announced or risk not having it accepted.
CS 184: Foundations of Computer Graphics page 1 of 12 Student Name: Student ID: Instructions: Read them carefully! The exam begins at 2:40pm and ends at 4:00pm. You must turn your exam in when time is
More informationHW Chapter 20 Q 2,3,4,5,6,10,13 P 1,2,3. Chapter 20. Classic and Modern Optics. Dr. Armen Kocharian
HW Chapter 20 Q 2,3,4,5,6,10,13 P 1,2,3 Chapter 20 Classic and Modern Optics Dr. Armen Kocharian Electromagnetic waves and matter: A Brief History of Light 1000 AD It was proposed that light consisted
More informationWhat s Missing? Brian Budge 5/31/04
What s Missing? Brian Budge budge@cs.ucdavis.edu 5/31/04 Institute for Data Analysis and Visualization : University of California, Davis What s wrong with these images? Slide 2 of 20 What can we do? More
More informationChapter 36. Diffraction. Copyright 2014 John Wiley & Sons, Inc. All rights reserved.
Chapter 36 Diffraction Copyright 36-1 Single-Slit Diffraction Learning Objectives 36.01 Describe the diffraction of light waves by a narrow opening and an edge, and also describe the resulting interference
More informationLecture 15: Shading-I. CITS3003 Graphics & Animation
Lecture 15: Shading-I CITS3003 Graphics & Animation E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012 Objectives Learn that with appropriate shading so objects appear as threedimensional
More informationVisualisatie BMT. Rendering. Arjan Kok
Visualisatie BMT Rendering Arjan Kok a.j.f.kok@tue.nl 1 Lecture overview Color Rendering Illumination 2 Visualization pipeline Raw Data Data Enrichment/Enhancement Derived Data Visualization Mapping Abstract
More informationColour Reading: Chapter 6. Black body radiators
Colour Reading: Chapter 6 Light is produced in different amounts at different wavelengths by each light source Light is differentially reflected at each wavelength, which gives objects their natural colours
More informationComputer graphics and visualization
CAAD FUTURES DIGITAL PROCEEDINGS 1986 63 Chapter 5 Computer graphics and visualization Donald P. Greenberg The field of computer graphics has made enormous progress during the past decade. It is rapidly
More informationRay Tracer Due date: April 27, 2011
Computer graphics Assignment 4 1 Overview Ray Tracer Due date: April 27, 2011 In this assignment you will implement the camera and several primitive objects for a ray tracer, and a basic ray tracing algorithm.
More informationPhilpot & Philipson: Remote Sensing Fundamentals Interactions 3.1 W.D. Philpot, Cornell University, Fall 12
Philpot & Philipson: Remote Sensing Fundamentals Interactions 3.1 W.D. Philpot, Cornell University, Fall 1 3. EM INTERACTIONS WITH MATERIALS In order for an object to be sensed, the object must reflect,
More informationSCIENCE 8 WORKBOOK. Chapter 5 Light Optics (Section 1) Ms. Jamieson This workbook belongs to:
SCIENCE 8 WORKBOOK Chapter 5 Light Optics (Section 1) Ms. Jamieson 2018 This workbook belongs to: Eric Hamber Secondary 5025 Willow Street Vancouver, BC Table of Contents A. Chapter 5.1 - The Ray Model
More informationrendering equation computer graphics rendering equation 2009 fabio pellacini 1
rendering equation computer graphics rendering equation 2009 fabio pellacini 1 physically-based rendering synthesis algorithms that compute images by simulation the physical behavior of light computer
More informationCoupling of surface roughness to the performance of computer-generated holograms
Coupling of surface roughness to the performance of computer-generated holograms Ping Zhou* and Jim Burge College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA *Corresponding author:
More informationA Simple Layered RGB BRDF Model
A Simple Layered RGB BRDF Model Xavier Granier, Wolfgang Heidrich To cite this version: Xavier Granier, Wolfgang Heidrich. A Simple Layered RGB BRDF Model. 10th Pacific Conference on Computer Graphics
More informationLecture 17: Recursive Ray Tracing. Where is the way where light dwelleth? Job 38:19
Lecture 17: Recursive Ray Tracing Where is the way where light dwelleth? Job 38:19 1. Raster Graphics Typical graphics terminals today are raster displays. A raster display renders a picture scan line
More informationAP* Optics Free Response Questions
AP* Optics Free Response Questions 1978 Q5 MIRRORS An object 6 centimeters high is placed 30 centimeters from a concave mirror of focal length 10 centimeters as shown above. (a) On the diagram above, locate
More informationRay Tracing. Kjetil Babington
Ray Tracing Kjetil Babington 21.10.2011 1 Introduction What is Ray Tracing? Act of tracing a ray through some scene Not necessarily for rendering Rendering with Ray Tracing Ray Tracing is a global illumination
More informationOptics. a- Before the beginning of the nineteenth century, light was considered to be a stream of particles.
Optics 1- Light Nature: a- Before the beginning of the nineteenth century, light was considered to be a stream of particles. The particles were either emitted by the object being viewed or emanated from
More informationVirtual Reality for Human Computer Interaction
Virtual Reality for Human Computer Interaction Appearance: Lighting Representation of Light and Color Do we need to represent all I! to represent a color C(I)? No we can approximate using a three-color
More informationOptics Test Science What are some devices that you use in everyday life that require optics?
Optics Test Science 8 Introduction to Optics 1. What are some devices that you use in everyday life that require optics? Light Energy and Its Sources 308-8 identify and describe properties of visible light
More informationLight Reflection Models
Light Reflection Models Visual Imaging in the Electronic Age Donald P. Greenberg October 21, 2014 Lecture #15 Goal of Realistic Imaging From Strobel, Photographic Materials and Processes Focal Press, 186.
More informationRay tracing based fast refraction method for an object seen through a cylindrical glass
20th International Congress on Modelling and Simulation, Adelaide, Australia, 1 6 December 2013 www.mssanz.org.au/modsim2013 Ray tracing based fast refraction method for an object seen through a cylindrical
More informationWhat is Color and How is It Measured?
Insight on Color Vol. 12, No. 5 What is Color and How is It Measured? The most important part of HunterLab s business is helping our customers to measure color. In this Applications Note, you will learn
More informationRetro-rendering with Vector-Valued Light: Producing Local Illumination from the Transport Equation
Retro-rendering with Vector-Valued Light: Producing Local Illumination from the Transport Equation David C. Banks and Kevin M. Beason Florida State University, Tallahassee, USA ABSTRACT Many rendering
More informationIllumination. The slides combine material from Andy van Dam, Spike Hughes, Travis Webb and Lyn Fong
INTRODUCTION TO COMPUTER GRAPHIC S Illumination The slides combine material from Andy van Dam, Spike Hughes, Travis Webb and Lyn Fong Andries van Dam October 29, 2009 Illumination Models 1/30 Outline Physical
More informationEfficient Rendering of Glossy Reflection Using Graphics Hardware
Efficient Rendering of Glossy Reflection Using Graphics Hardware Yoshinori Dobashi Yuki Yamada Tsuyoshi Yamamoto Hokkaido University Kita-ku Kita 14, Nishi 9, Sapporo 060-0814, Japan Phone: +81.11.706.6530,
More informationProperties of Light I
Properties of Light I Light definition Light Spectrum Wavelength in nm (1nm = 10-7 cm) Visible/White Light Cosmic Gamma X-Rays Ultra Violet Infra Red Micro Waves Radio Waves 1 Theory of Light Two complimentary
More informationMET 4410 Remote Sensing: Radar and Satellite Meteorology MET 5412 Remote Sensing in Meteorology. Lecture 9: Reflection and Refraction (Petty Ch4)
MET 4410 Remote Sensing: Radar and Satellite Meteorology MET 5412 Remote Sensing in Meteorology Lecture 9: Reflection and Refraction (Petty Ch4) When to use the laws of reflection and refraction? EM waves
More informationCSE 167: Introduction to Computer Graphics Lecture #6: Colors. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2013
CSE 167: Introduction to Computer Graphics Lecture #6: Colors Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2013 Announcements Homework project #3 due this Friday, October 18
More informationDispersion Polarization
Dispersion Polarization Phys Phys 2435: 22: Chap. 33, 31, Pg 1 Dispersion New Topic Phys 2435: Chap. 33, Pg 2 The Visible Spectrum Remember that white light contains all the colors of the s p e c t r u
More informationNoncontact measurements of optical inhomogeneity stratified media parameters by location of laser radiation caustics
Noncontact measurements of optical inhomogeneity stratified media parameters by location of laser radiation caustics Anastasia V. Vedyashkina *, Bronyus S. Rinkevichyus, Irina L. Raskovskaya V.A. Fabrikant
More informationChapter 26 Geometrical Optics
Chapter 26 Geometrical Optics 26.1 The Reflection of Light 26.2 Forming Images With a Plane Mirror 26.3 Spherical Mirrors 26.4 Ray Tracing and the Mirror Equation 26.5 The Refraction of Light 26.6 Ray
More informationEM Waves Practice Problems
PSI AP Physics 2 Name 1. Sir Isaac Newton was one of the first physicists to study light. What properties of light did he explain by using the particle model? 2. Who was the first person who was credited
More informationName Section Date. Experiment Reflection and Refraction
Name Section Date Introduction: Experiment Reflection and Refraction The travel of light is often represented in geometric optics by a light ray, a line that is drawn to represent the straight-line movement
More informationRay Tracing. Brian Curless CSEP 557 Fall 2016
Ray Tracing Brian Curless CSEP 557 Fall 2016 1 Reading Required: Shirley, section 10.1-10.7 (online handout) Triangle intersection (online handout) Further reading: Shirley errata on syllabus page, needed
More informationSpectral Color and Radiometry
Spectral Color and Radiometry Louis Feng April 13, 2004 April 13, 2004 Realistic Image Synthesis (Spring 2004) 1 Topics Spectral Color Light and Color Spectrum Spectral Power Distribution Spectral Color
More informationRay Tracing. CSCI 420 Computer Graphics Lecture 15. Ray Casting Shadow Rays Reflection and Transmission [Ch ]
CSCI 420 Computer Graphics Lecture 15 Ray Tracing Ray Casting Shadow Rays Reflection and Transmission [Ch. 13.2-13.3] Jernej Barbic University of Southern California 1 Local Illumination Object illuminations
More informationCOMP371 COMPUTER GRAPHICS
COMP371 COMPUTER GRAPHICS SESSION 15 RAY TRACING 1 Announcements Programming Assignment 3 out today - overview @ end of the class Ray Tracing 2 Lecture Overview Review of last class Ray Tracing 3 Local
More informationPHYS:1200 LECTURE 32 LIGHT AND OPTICS (4)
1 PHYS:1200 LECTURE 32 LIGHT AND OPTICS (4) The first three lectures in this unit dealt with what is for called geometric optics. Geometric optics, treats light as a collection of rays that travel in straight
More informationindex of refraction-light speed
AP Physics Study Guide Chapters 22, 23, 24 Reflection, Refraction and Interference Name Write each of the equations specified below, include units for all quantities. Law of Reflection Lens-Mirror Equation
More informationLab2: Single Photon Interference
Lab2: Single Photon Interference Xiaoshu Chen* Department of Mechanical Engineering, University of Rochester, NY, 14623 ABSTRACT The wave-particle duality of light was verified by multi and single photon
More informationChapter 15. Light Waves
Chapter 15 Light Waves Chapter 15 is finished, but is not in camera-ready format. All diagrams are missing, but here are some excerpts from the text with omissions indicated by... After 15.1, read 15.2
More informationRAYTRACING. Christopher Peters INTRODUCTION TO COMPUTER GRAPHICS AND INTERACTION. HPCViz, KTH Royal Institute of Technology, Sweden
DH2323 DGI15 INTRODUCTION TO COMPUTER GRAPHICS AND INTERACTION RAYTRACING HPCViz, KTH Royal Institute of Technology, Sweden http://kth.academia.edu/christopheredwardpeters Based on DGI12 notes by Carl
More informationRay Optics. Ray model Reflection Refraction, total internal reflection Color dispersion Lenses Image formation Magnification Spherical mirrors
Ray Optics Ray model Reflection Refraction, total internal reflection Color dispersion Lenses Image formation Magnification Spherical mirrors 1 Ray optics Optical imaging and color in medicine Integral
More information