Hemispherical Confocal Imaging Using Turtleback Reflector

Mukaigawa, Yasuhiro; Tagawa, Seiichi; Kim, Jae-Won; Raskar, Ramesh; Matsushita, Yasuyuki; Yagi, Yasushi

doi:10.1007/978-3-642-19315-6_26

Cited by 17 publications

(30 citation statements)

References 27 publications

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“…It is technically difficult to realize an instrument capable of acquiring thousands of images with different illumination and observation directions of the sample surface within reasonable time, so there is only few realized BTF setups. Portable BTF measurement setups are rare, but a few can be found that could be realized as portable ones [5,6,7,8,9,10,11]. Our instrument for BTF on site measurement was designed as a compact and portable system which tackles the dimension issues and acquisition speed enhancement by a combination of the parallelization of the illuminators and cameras with their mutual motions regarding the sample surface [1].…”

Section: The Btf Measurement Instrumentmentioning

confidence: 99%

Laser Imaging Approach for Portable BTF Measurement System Automatic Alignment

2018

IJOMAM

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The paper presents a new alignment sensing possibility for automation of BTF instrument with regards to the sample surface. We have developed a portable bidirectional texture function (BTF) measurement instrument allowing for on-site measurement outside the laboratory. It is a newly emerging technique enabling data acquisition of the real objects without the necessity of their extraction from the environment. A practical issue of the sample measurement is the instrument alignment against the measured surface. The system is provided with five degrees of freedom to be able to set the right position of the instrument to the sample surface without the necessity of the sample manipulation. We used a laser auto-collimation principle to provide feedback information for the system alignment. Now we propose a new approach for acquisition of the feedback information for the system alignment based on laser-imaging approach. We present theoretic relations of the proposed system and technical demands to reach the desired uncertainty of the system misalignment to the sample surface of less than 0.1°.

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Section: The Btf Measurement Instrumentmentioning

confidence: 99%

Laser Imaging Approach for Portable BTF Measurement System Automatic Alignment

2018

IJOMAM

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“…Mukaigawa et al . [MTK*11] designed a polyhedral mirror based on the geometric properties of ellipsoids for a design that allows the placement of objects at one focal point and a camera at the other to perform hemispherical confocal imaging.…”

Section: Basics and Related Workmentioning

confidence: 99%

“…In contrast to Mukaigawa et al . [MTK*11], we provide a user guided optimization pipeline for the derivation of the geometric configuration.…”

Section: Basics and Related Workmentioning

confidence: 99%

Design and Fabrication of Faceted Mirror Arrays for Light Field Capture

Fuchs

Kächele

Rusinkiewicz

2013

Computer Graphics Forum

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The high resolution of digital cameras has made single-shot, single-sensor acquisition of light fields feasible, though considerable design effort is still necessary in order to construct the necessary collection of optical elements for particular acquisition scenarios. This article explores a pipeline for designing, fabricating, and utilizing faceted mirror arrays which simplifies this task. The foundation of the pipeline is an interactive tool that automatically optimizes for mirror designs while exposing to the user a set of intuitive parameters for light field quality and manufacturing constraints. We investigate two manufacturing processes for automatic fabrication of the resulting designs: one is based on CNC milling, polishing, and plating of one solid work piece, while the other involves assembly of precision cut mirror facets. We demonstrate results for refocusing in a macro photography scenario.

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“…The measurement is usually made in a laboratory under well-controlled conditions. The widely used method relies on imagebased bidirectional reflectance distribution function (BRDF) measurement [2,10,12,13] by capturing many images of the material sample with different known light directions. Moreover, joint shape and reflectance recovery using images is even more challenging, particularly under uncontrolled illuminations.…”

Section: Introductionmentioning

confidence: 99%

Reflectance and Shape Estimation with a Light Field Camera under Natural Illumination

Ngo

Nagahara

Nishino

et al. 2017

Procedings of the British Machine Vision Conference 2017

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Reflectance and shape are two important components in visually perceiving the real world. Inferring the reflectance and shape of an object through cameras is a fundamental research topic in the field of computer vision. While three-dimensional shape recovery is pervasive with varieties of approaches and practical applications, reflectance recovery has only emerged recently. Reflectance recovery is a challenging task that is usually conducted in controlled environments, such as a laboratory environment with a special apparatus. However, it is desirable that the reflectance be recovered in the field with a handy camera so that reflectance can be jointly recovered with the shape. To that end, we present a solution that simultaneously recovers the reflectance and shape (i.e., dense depth and normal maps) of an object under natural illumination with commercially available handy cameras. We employ a light field camera to capture one light field image of the object, and a 360-degree camera to capture the illumination. The proposed method provides promising results in simulation and real-world experiments.

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Hemispherical Confocal Imaging Using Turtleback Reflector

Cited by 17 publications

References 27 publications

Laser Imaging Approach for Portable BTF Measurement System Automatic Alignment

Laser Imaging Approach for Portable BTF Measurement System Automatic Alignment

Design and Fabrication of Faceted Mirror Arrays for Light Field Capture

Reflectance and Shape Estimation with a Light Field Camera under Natural Illumination

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