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ange map is always contaminated with noise. The smoothing step can be consideredto be a restoration process accomplished by local deformation in 3D space.Manytechniques developed in 2D image processing cannot be applied to surface processing.Common problems in surface smoothing are loss of details and shrinkage. A successfulsurface smoothing algorithm should be able to efficiently suppress noise while makingthe deformation faithful to the original measurement and preserving the features on thesurface.A full 3D reconstruction requires scanning from different views. The surface measuredfrom each scan is recorded in a local coordinate system centered at the scanner. Inorder to integrate different views, all the surfaces must be registered into a global coordinatesystem. Although the pose of the range scanner sometimes can be approximatelyobtained from the servo system of a carrier such as a robot, an automatic registrationfrom the measurement is still crucial. A human is capable of understanding the environmentwithout knowing the exact coordinate transformation when he is walking around.It is still not clear how to simulate this human ability on the computer. However, effortsin the field of computer vision are currently focusing on estimating the pose mathematicallyby matching the surfaces. The challenges in automatic registration are how toefficiently find correspondences from two partially overlapped surfaces and robustly dealwith the noise and different surface sampling resolutions.Integrating surfaces from different views is a fusion process that weaves a wholesurface from a set of overlapping surface patches. The integration process should be4
obust to surface noise and registration error. It should also handle other modalities suchas color images which generate a textured model. Usually, it is impossible to scan thewhole object, so holes are left at regions where the laser cannot reach. These holes canbe filled by space carving during the integration or by an automatic hole filling processafter integration. Choosing space carving or leaving holes during the integration dependson the completeness of the data. After the surface is reconstructed, post-processing isnecessary to further smooth the surface and remove the outliers. Sometimes geometriccompression is needed for a real time rendering of the reconstructed surface.The reconstructed surface may contain a number of parts. In many cases, a segmentationor decomposition of the surface gives a better interpretation of the surface.Surface segmentation is a higher level of surface processing which partitions the surfaceinto different meaningful parts. Segmenting a surface is different from segmenting a 2Dimage in that the segmentation is guided by geometric variation instead of gray levelvariation and a surface is not defined on a regular grid. However, 2D image segmentationmethods can be extended to surface segmentation. A good segmentation algorithmshould be efficient, robust to surface noise, and close to human perception.1.3 ContributionsThe contributions of this research are summarized as follows.5
Page 1 and 2: To the Graduate Council:I am submit
Page 3 and 4: Copyright c○ Yiyong Sun, 2002All
Page 5 and 6: AcknowledgmentsFirst and foremost,
Page 7 and 8: search employs an implicit surface-
Page 9 and 10: 3.2.2 Edge Preservation for Range D
Page 11 and 12: 8.2 Future Research . . . .........
Page 13 and 14: List of Figures1.1 A framework for
Page 15 and 16: 7.14 Finding corresponding points o
Page 17 and 18: Chapter 1IntroductionThis introduct
Page 19: Range ImageSmoothingRegistrationCol
Page 23 and 24: more efficient than 2D image correl
Page 25 and 26: scending path, and region merging.L
Page 27 and 28: two-dimensional (2D) image, 2D lowp
Page 29 and 30: curvatures of points on a surface i
Page 31 and 32: smoothing on the surface mesh. Shri
Page 33 and 34: with different surface representati
Page 35 and 36: center point and every surface poin
Page 37 and 38: Table 2.1: Comparison of different
Page 39 and 40: Reconstruction from Unorganized Poi
Page 41 and 42: tional. An offset of the distance f
Page 43 and 44: surement confidence. However, in or
Page 45 and 46: triangle mesh. The triangle mesh is
Page 47 and 48: mesh segmentation based on the phys
Page 49 and 50: Rettmann et al. [70] proposed a mes
Page 51 and 52: successful smoothing for both raw r
Page 53 and 54: where lim t→0 (R/t) =0,H represen
Page 55 and 56: the range r ij is estimated instead
Page 57 and 58: y minimizing the following energy f
Page 59 and 60: tions were used:r α = r i,j+1 −
Page 61 and 62: where κ represents a parameter tha
Page 63 and 64: inequality, such asI∑I∑S i ≤
Page 65 and 66: n ′ in iT ipqn ipw in ′ i−→
Page 67: The singular value decomposition is
Page 70 and 71:
a limit on sharp edges. This limit
Page 72 and 73:
of the smoothing.Surface smoothing
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fingerprint are presented. Section
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erroneously includes surface patch
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(ρ, θ)ρθT p (S)expSexp p (ρ,
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exponential map is introduced.4.2 F
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accurately than Dijkstra’s algori
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andθ = arccos ρ2 (A)+|AB| 2 −
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andy =((n × −→ pm) × n) · v
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images.4.3 Candidate Point Selectio
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(a)(b)(c)(d)Figure 4.6: Global fing
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and R ij is below a threshold. The
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If the singular-value decomposition
Page 96 and 97:
Chapter 5Surface Reconstruction fro
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Figure 5.2: Two registered and over
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Figure 5.4: Intersecting triangles.
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Figure 5.7: Gap between surfaces af
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5.2 Volume-Based Surface Integratio
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2D texture coordinate of x is set t
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ABFigure 5.9: Hole filling illustra
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are presented in Section 7.4.6.1 A
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6.3 Applying the Fast Marching Wate
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Algorithm 6.2 (Fast Marching Waters
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15: end if16: if v i.h
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6.3.2 Geodesic ErosionThis step ass
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(a)(b)(c)(d)Figure 6.3: Segmenting
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Chapter 7Experimental ResultsThis c
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no discernible improvement. For fai
Page 126 and 127:
(a)(b)(c)(d)Figure 7.4: Surface smo
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(a)(b)(c)(d)Figure 7.6: Smoothing s
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(a)(b)(c)(d)(e)(f)Figure 7.8: Adapt
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The real range images were scanned
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(a)(b)Figure 7.10: Registration of
Page 136 and 137:
(a)(b)(c)(d)(e)(f)Figure 7.12: Matc
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(a) (b) (c) (d)(e) (f) (g) (h)(i)(j
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(a)(b)ICP Registration Error (mm)21
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(a)(b)(c)(d)(e)(f)Figure 7.17: Surf
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Table 7.1: Small parts 3D reconstru
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(a)(b)(c)(d)Figure 7.21: Surface mo
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(a)(b)Figure 7.23: Automatic hole f
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(a)(b)(c)(d)(e)(f)(g)(h)Figure 7.25
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(a)(b)(c)(d)Figure 7.27: Four-view
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(a)(b)(c)(d)Figure 7.28: Segmentati
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(a)(b)(c)(d)Figure 7.30: Surface se
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Table 7.2: Performance of the fast
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surface reconstructed from the raw
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to choose a proper flowing step siz
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of interest based on the shape irre
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8.2 Future ResearchThere are many o
Page 168 and 169:
Bibliography[1] E. L. Allgower and
Page 170 and 171:
[26] G. Dziuk and J. E. Hutchinson.
Page 172 and 173:
[54] W. E. Lorensen and H. E. Cline
Page 174 and 175:
[81] M. Soucy and D. Laurendeau. A
Page 176 and 177:
[106] S. M. Yamany, A. A. Farag, an
Page 178 and 179:
Appendix ALaser Range ScannersLaser
Page 180 and 181:
(a)(b)Transmitter LensTargetDiodeLa
Page 182 and 183:
A.2 Scanners Based on Laser Triangu
Page 184 and 185:
LaserBaseline B-s0saOpticalCenter(a
Page 186 and 187:
Appendix BSimplification of theArea
Page 188:
VitaYiyong Sun was born in Beijing,
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