國立虎尾科技大學 |

Photometric Stereo with Discrete Geometry Processing.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Photometric Stereo with Discrete Geometry Processing./
Author:	Xie, Wuyuan.
Description:	1 online resource (108 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 78-05(E), Section: B.
Contained By:	Dissertation Abstracts International78-05B(E).
Subject:	Mechanical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9781369410785

Photometric Stereo with Discrete Geometry Processing.
Xie, Wuyuan.

Photometric Stereo with Discrete Geometry Processing. - 1 online resource (108 pages)

Source: Dissertation Abstracts International, Volume: 78-05(E), Section: B.

Thesis (Ph.D.)

Includes bibliographical references

In this thesis, we first analyze the reconstruction problem of photometric stereo and shape from shading (SfS), and propose an efficient method to reconstruct the surface from gradients (SfG). Our method is formulated based on the framework of discrete geometry processing. Unlike the existing SfG approaches, we transfer the continuous reconstruction problem into the discrete space and efficiently solve the problem via a sequence of least-square optimization steps. Our discrete formulation brings three main advantages: 1) the reconstruction preserves sharp-features, 2) sparse/incomplete set of gradients can be well handled, and 3) domains of computation can have irregular boundaries. Our solution is direct and easy to implement, and the comparisons with the state-of-the-arts show the effectiveness of our method.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9781369410785Subjects--Topical Terms:

557493
Mechanical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

Photometric Stereo with Discrete Geometry Processing.
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035 $a (MiAaPQ)AAI10297360
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099 $a TUL $f hyy $c available through World Wide Web
100 1 $a Xie, Wuyuan. $3 1180403
245 1 0 $a Photometric Stereo with Discrete Geometry Processing.
264 0 $c 2016
300 $a 1 online resource (108 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertation Abstracts International, Volume: 78-05(E), Section: B.
500 $a Adviser: Kin Chuen Hui.
502 $a Thesis (Ph.D.) $c The Chinese University of Hong Kong (Hong Kong) $d 2016.
504 $a Includes bibliographical references
520 $a In this thesis, we first analyze the reconstruction problem of photometric stereo and shape from shading (SfS), and propose an efficient method to reconstruct the surface from gradients (SfG). Our method is formulated based on the framework of discrete geometry processing. Unlike the existing SfG approaches, we transfer the continuous reconstruction problem into the discrete space and efficiently solve the problem via a sequence of least-square optimization steps. Our discrete formulation brings three main advantages: 1) the reconstruction preserves sharp-features, 2) sparse/incomplete set of gradients can be well handled, and 3) domains of computation can have irregular boundaries. Our solution is direct and easy to implement, and the comparisons with the state-of-the-arts show the effectiveness of our method.
520 $a In the real system aspect, we improve it based on the above proposed reconstruction: We tackle the problem of photometric stereo (PS) under the near point lighting in this work. Different from the conventional photometric stereo that assumes the parallel lighting, photometric stereo under the near point lighting condition is a nonlinear problem as the local surface normals are coupled with its distance to the camera as well as the light sources. To solve this non-linear problem, a local/global mesh deformation approach is developed to determine the position and the orientation of a facet simultaneously, where each facet is corresponding to a pixel in the image captured by the camera. Unlike traditional nonlinear optimizations, the mesh deformation in our approach is decoupled into an iteration of interlaced steps of the local projection and the global blending. Experimental results verify that our method generates accurate estimation of surface shape under the near point lighting in a few iterations. Besides, this approach is robust to errors on the positions of light sources and is easy to be implemented.
520 $a Finally, to support the real system, we give a general lighting calibration method. Although several techniques have been developed for estimating the light source position in the indoor or outdoor environment, those techniques assume that the light source can be approximated by a point, which cannot be applied safely to photometric stereo reconstruction, especially when the light source is placed quite close to a target. In this case, size of the light source cannot be ignored. In this work, we present a novel approach in estimating the light source from single image of a scene that is illuminated by a near-surface source. We propose to employ a shiny sphere and a Lambertion plate to locate light source position, where albedo variance of the Lambertian plate is used to build the basis of the object function. In addition, we show the convexity of this object function and propose an efficient way to search the optimal source position. We test our calibration results on real images by photometric stereo reconstruction and image rendering, and both testing results show the accuracy of our estimation framework.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Mechanical engineering. $3 557493
655 7 $a Electronic books. $2 local $3 554714
690 $a 0548
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a The Chinese University of Hong Kong (Hong Kong). $3 1180404
773 0 $t Dissertation Abstracts International $g 78-05B(E).
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10297360 $z click for full text (PQDT)