Estimation of fluorescent Donaldson matrices using a spectral imaging system

Tominaga, Shoji; Hirai, Keita; Horiuchi, Takahiko

doi:10.1364/oe.26.002132

Cited by 10 publications

(6 citation statements)

References 25 publications

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“…Then we tested our system for indoor scene archiving. In addition, we relighted an omnidirectional indoor scene, since spectral imaging is useful for illumination simulation [42,44,63,64].…”

Section: Gigapixel Image Relighting Of Indoor Arichived Scenementioning

confidence: 99%

High-Dynamic-Range Spectral Imaging System for Omnidirectional Scene Capture

et al. 2018

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Omnidirectional imaging technology has been widely used for scene archiving. It has been a crucial technology in many fields including computer vision, image analysis and virtual reality. It should be noted that the dynamic range of luminance values in a natural scene is quite large, and the scenes containing various objects and light sources consist of various spectral power distributions. Therefore, this paper proposes a system for acquiring high dynamic range (HDR) spectral images for capturing omnidirectional scenes. The system is constructed using two programmable high-speed video cameras with specific lenses and a programmable rotating table. Two different types of color filters are mounted on the two-color video cameras for six-band image acquisition. We present several algorithms for HDR image synthesis, lens distortion correction, image registration, and omnidirectional image synthesis. Spectral power distributions of illuminants (color signals) are recovered from the captured six-band images based on the Wiener estimation algorithm. In this paper, we present two types of applications based on our imaging system: time-lapse imaging and gigapixel imaging. The performance of the proposed system is discussed in detail in terms of the system configurations, acquisition time, artifacts, and spectral estimation accuracy. Experimental results in actual scenes demonstrate that the proposed system is feasible and powerful for acquiring HDR spectral scenes through time-lapse or gigapixel omnidirectional imaging approaches. Finally, we apply the captured omnidirectional images to time-lapse spectral Computer Graphics (CG) renderings and spectral-based relighting of an indoor gigapixel image.

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Section: Gigapixel Image Relighting Of Indoor Arichived Scenementioning

confidence: 99%

High-Dynamic-Range Spectral Imaging System for Omnidirectional Scene Capture

et al. 2018

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“…The spectral imaging system used for spectral image acquisition consisted of a monochrome CCD camera with Peltier cooling, 12-bit dynamic range, 1280-by-1024 pixel resolution, a VariSpec liquid crystal tunable filter, an IR cut filter, and a personal computer (see 13 ). The spectral images of fluorescent objects were captured at 5 nm intervals in the visible wavelength range (400-700 nm); thus, each captured image was represented in an array of 61-dimensional vectors.…”

Section: Equipment and Data Acquisitionmentioning

confidence: 99%

“…Several approaches have been proposed for estimating the Donaldson matrix using various types of imaging systems, such as RGB cameras, 17 multiband imaging systems, 18,19 and spectral imaging systems. 4,13 Let us represent the Donaldson matrix as a twovariable function D λ em , λ ex ð Þof the excitation wavelength λ ex and the emission/reflection wavelength λ em . The excitation wavelength for many fluorescent materials starts from approximately 330 to 350 nm (see 16 ).…”

Section: Bispectral Model Of a Fluorescent Objectmentioning

confidence: 99%

“…However, these measurement methods were inconvenient and impractical in ordinary scenes using an imaging system. Several approaches have been proposed for estimating the Donaldson matrix using various types of imaging systems, such as RGB cameras, 17 multiband imaging systems, 18,19 and spectral imaging systems 4,13 …”

Section: Data Acquisition and Appearance Modelingmentioning

confidence: 99%

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Appearance synthesis of fluorescent objects with mutual illumination effects

Tominaga

Guarnera

2021

Color Research & Application

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We propose an approach for the appearance synthesis of objects with matte surfaces made of arbitrary fluorescent materials, accounting for mutual illumination. We solve the problem of rendering realistic scene appearances of objects placed close to each other under different conditions of uniform illumination, viewing direction, and shape, relying on standard physically based rendering and knowledge of the three‐dimensional shape and bispectral data of scene objects. The appearance synthesis model suggests that the overall appearance is decomposed into five components, each of which is expanded into a multiplication of spectral functions and shading terms. We show that only two shading terms are required, related to (a) diffuse reflection by direct illumination and (b) interreflection between two matte surfaces. The Mitsuba renderer is used to estimate the reflection components based on the underlying Monte Carlo simulation. The spectral computation of the fluorescent component is performed over a broad wavelength range, including ultraviolet and visible wavelengths. We also address a method for compensating for the difference between the simulated and real images. Experiments were performed to demonstrate the effectiveness of the proposed appearance synthesis approach. The accuracy of the proposed approach was experimentally confirmed using objects with different shapes and fluorescence in the presence of complex mutual illumination effects.

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“…Databases of such measurements are available online, see for instance [May19, The19]. Tominaga et al [THH18] estimate reradiation matrices from images. Hullin et al [HHA∗10] capture high dimensional bidirectional bispectral reflectance and reradiation distribution functions (BBRRDF) both in the wavelength and angular domains.…”

Section: Background and Related Workmentioning

confidence: 99%

Spectral Mollification for Bidirectional Fluorescence

Jung

Hanika

Dachsbacher

2020

Computer Graphics Forum

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Fluorescent materials can shift energy between wavelengths, thereby creating bright and saturated colors both in natural and artificial materials. However, rendering fluorescence for continuous wavelengths or combined with wavelength dependent path configurations so far has only been feasible using spectral unidirectional methods. We present a regularization‐based approach for supporting fluorescence in a spectral bidirectional path tracer. Our algorithm samples camera and light sub‐paths with independent wavelengths, and when connecting them mollifies the BSDF at one of the connecting vertices such that it reradiates light across multiple wavelengths. We discuss arising issues such as color bias in early iterations, consistency of the method and MIS weights in the presence of spectral mollification. We demonstrate our method in scenes combining fluorescence and transport phenomena that are difficult to render with unidirectional or spectrally discrete methods.

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Estimation of fluorescent Donaldson matrices using a spectral imaging system

Cited by 10 publications

References 25 publications

High-Dynamic-Range Spectral Imaging System for Omnidirectional Scene Capture

High-Dynamic-Range Spectral Imaging System for Omnidirectional Scene Capture

Appearance synthesis of fluorescent objects with mutual illumination effects

Spectral Mollification for Bidirectional Fluorescence

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