Usability of Digital Cameras for Verifying Physically Based ...

More documents

Recommendations

Info

struction algorithms have been developed to implement the process of reconstruct- ing a 3-dimensional object from these images. Bergner et al. [BDCM05] used a physically based rendering toolkit to simplify the programming of tomography algorithms in order to speed up the development and testing processes of novel algorithms. As the quality of the diagnosis relies heavily on the accuracy of the reconstruction algorithm, the correctness of the rendering toolkit again has to be guaranteed. 1.3.4 Safety Checks Physically based rendering is also useful when it comes to safety relevant applications. In car industry, for example, the design of a car interior has to fulfill certain safety relevant issues. One of these issues is e.g. that the reflections in the windshield are to be minimized in a way that they do not distract the driver. Under daylight conditions these reflections are mainly caused by glossy materials in the upper part of a cockpit mirroring in the windshield. Under night light conditions, ambient light sources or illuminated switches can cause a similar effect. A real- istic rendering of the car interior helps the designer to select suitable materials and to position the light sources in an appropriate way. 1.4 Thesis Contribution The main contribution of this thesis is to find as many meaningful ways of using a digital camera for verifying a physically based rendering system as possible in order to provide a practicable method for any development environment. The methods were taken from the field of color management. Additionally another method was developed as part of this thesis. We compared the usability and prac- ticability of all the methods, focusing on required equipment and cost. We also investigated the factor of improvement that methods requiring expensive equipment bring. Using a photograph for verifying the results of a rendering system seems obvious and some developers may have started to use it already, but as far as we know no exhaustive analysis apart from our work has been published, yet. In our rendering system, we use spectral values for internal calculations. Some of the verification methods are based on XYZ color space though, which raises the question why we do not use XYZ as internal color space from the first. The reason is that we found a severe problem that can occur when interactions of light and 4
matter are calculated in XYZ space. The details of this work are explained in [UW06]. Verification in general is quite often neglected in the development process. We composed an extensive state of the art report on the topic of “Verification of Physically Based Rendering Algorithms” (see [UWP05] and [UWP06]) in order to call attention to the importance of this field. 1.5 Thesis Outline This thesis is organized as follows: Chapter 2 presents an overview on verification techniques, from the well-known Cornell Box to recent developments. A short introduction to the field of colorimetry is given in chapter 3. Chapters 4 and 5 describe the internal functionalities of a digital camera and a physically based rendering system as far as they are used in this thesis, respectively. The procedure of data acquisition and processing is outlined in chapter 6. Chapter 7 is dedicated to the main topic of this thesis – various approaches of using a digital camera for verifying a physically based rendering system. The question of why we rely on spectral rendering instead of using XYZ space as internal color space is answered in chapter 8. Conclusions are drawn in chapter 9 along with a discussion of future work. Appendix A explains photometric and radiometric quantities that are used throughout the thesis, whereas appendix B describes various types of measurement devices. Several instruments that were used for data acquisition are illustrated in appendix C. Appendix D gives a number of websites that contain publicly available validation data. Detailed results of the tests made in conjunction with this thesis are listed in appendix E. 5
Page 1 and 2: DISSERTATION Usability of Digital C
Page 3 and 4: Kurzfassung Physically Based Render
Page 5 and 6: Acknowledgements I want to thank We
Page 7 and 8: 3 Colorimetry 32 3.1 Color Spaces .
Page 9 and 10: E.5 Treating the Camera as a Black
Page 11 and 12: 20 The CIE 1931 chromaticity diagra
Page 13 and 14: 53 (a) Density plot for using the c
Page 15 and 16: List of Tables 1 Camera settings th
Page 17 and 18: 1 Introduction In recent years, a l
Page 19: 1.3 Applications of Physically Base
Page 23 and 24: Figure 2: A photograph of the real
Page 25 and 26: (a) Photo (b) Default (c) 2 Bounces
Page 27 and 28: y a light source on top of the cube
Page 29 and 30: Figure 7: Points A to F were select
Page 31 and 32: Figure 9: A difference image of pho
Page 33 and 34: Figure 12: From top to bottom: a hi
Page 35 and 36: (a) Figure 13: (a) Left side: measu
Page 37 and 38: Figure 14: Six photocells were posi
Page 39 and 40: Figure 16: The left image shows a r
Page 41 and 42: (a) (b) Figure 18: (a) The validati
Page 43 and 44: shape of the caustic. 2.3 Analytica
Page 45 and 46: two test cases, but instead of the
Page 47 and 48: segments of the sphere and its actu
Page 49 and 50: of luminance [GJB80]. In XYZ color
Page 51 and 52: where L ∗ � � Y m = 903.3 Yn
Page 53 and 54: (a) (b) Figure 21: Chromaticity dia
Page 55 and 56: 4 Digital Cameras Pattanaik et al.
Page 57 and 58: Figure 23: The RAW image data is co
Page 59 and 60: 5 Physically Based Rendering System
Page 61 and 62: see section 7.4. By avoiding XYZ sp
Page 63 and 64: Figure 27: The sensor plane marking
Page 65 and 66: (a) (b) Figure 30: (a) ColorChecker
Page 67 and 68: available on MAC systems. We chose
Page 69 and 70: (a) (b) (c) Figure 34: Standard dev
Page 71 and 72:
Figure 35: Eighty measurement spots
Page 73 and 74:
(a) (b) (c) (d) Figure 37: (a) Lumi
Page 75 and 76:
(a) (b) Figure 40: (a) Luminance di
Page 77 and 78:
i \ j 0 1 2 3 4 5 6 7 8 9 10 11 12
Page 79 and 80:
(a) (b) (c) (d) Figure 43: (a) Lumi
Page 81 and 82:
(a) (b) Figure 46: Standard deviati
Page 83 and 84:
(a) (b) Figure 49: (a) The measurem
Page 85 and 86:
of each patch using a spectrophotom
Page 87 and 88:
Figure 51: L ∗ a ∗ b ∗ differ
Page 89 and 90:
(a) (b) Figure 53: (a) Density plot
Page 91 and 92:
(a) (b) (c) Figure 55: Histograms o
Page 93 and 94:
Using an ICC profile obviously impr
Page 95 and 96:
(a) (b) (c) (d) Figure 58: Histogra
Page 97 and 98:
5 6 7 8 9 10 11 Min 0.50 0.49 0.13
Page 99 and 100:
in the light transport simulation o
Page 101 and 102:
the internal data of a camera and w
Page 103 and 104:
etter results: One can measure the
Page 105 and 106:
Figure 62: A Mathematica generated
Page 107 and 108:
their internal color space. This mi
Page 109 and 110:
Figure 66: Surface reflectance valu
Page 111 and 112:
as bad compared to other methods. S
Page 113 and 114:
in sufficient detail. The approach
Page 115 and 116:
A Radiometric and Photometric Quant
Page 117 and 118:
B.6 Goniophotometer A goniophotomet
Page 119 and 120:
C.3 Color Chart Figure 68: A Konica
Page 121 and 122:
D Web Resources of Validation Data
Page 123 and 124:
8 bit jpg 16 bit 29 11.58 11.52 11.
Page 125 and 126:
8 bit jpg 16 bit 91 17.21 17.11 17.
Page 127 and 128:
E.2 Using an ICC Profile 8 bit jpg
Page 129 and 130:
8 bit jpg 16 bit 62 16.10 16.08 16.
Page 131 and 132:
8 bit jpg 16 bit 124 11.08 10.89 11
Page 133 and 134:
1 2 3 4 31 9.10 3.61 4.26 5.96 32 8
Page 135 and 136:
1 2 3 4 93 6.25 4.11 4.05 8.69 94 4
Page 137 and 138:
E.4 Adaptive Mapping - Higher Order
Page 139 and 140:
5 6 7 8 9 10 11 62 3.42 2.52 2.51 2
Page 141 and 142:
5 6 7 8 9 10 11 124 2.10 2.14 2.96
Page 143 and 144:
R G B 31 -38.94 -25.49 29.26 32 -9.
Page 145 and 146:
R G B 93 103.86 109.28 55.06 94 31.
Page 147 and 148:
References [3dS06] 3D Studio Max: w
Page 149 and 150:
[HLR00] Guowei Hong, M. Ronnier Luo
Page 151 and 152:
Color Imaging Conference, pages 250
Page 153:
[VMKK00] V. Volevich, K. Myszkowski
show all

Usability of Digital Cameras for Verifying Physically Based ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?