復(fù)雜幾何對象高精度數(shù)字化重建理論與方法

楊必勝　張帆　方莉娜　臧玉府　王晏民　侯妙樂　趙仁亮

摘 要：該研究的目標(biāo)：研究多源、異構(gòu)數(shù)據(jù)特征感知與融合的技術(shù)與方法，針對文化遺產(chǎn)的數(shù)字化復(fù)原需求，研究多源數(shù)據(jù)融合的文化遺產(chǎn)高精度重構(gòu)方法，建立文化遺產(chǎn)的多尺度高精度表達(dá)模型，為文化遺產(chǎn)數(shù)字化存檔、虛擬修復(fù)、個性化展示等提供科學(xué)依據(jù)。為此，我們提出了一種基于空間曲率特征和形狀特征的高精度點云自動配準(zhǔn)方法。在曲率特征點的計算基礎(chǔ)上利用點云聚類傳播和脊線提取技術(shù)，提取出信息量豐富的三維脊線，融合形變能量模型和最小二乘匹配方法，全面地描述空間曲線的形狀特征，同時利用曲線間的空間關(guān)系和最佳轉(zhuǎn)換參數(shù)篩選策略，完成高精度點云自動配準(zhǔn)。通同時提出了一種基于興趣邊緣優(yōu)化的壁畫影像與激光掃描數(shù)據(jù)非剛性配準(zhǔn)和高精度紋理映射方法。利用激光掃描數(shù)據(jù)的強度信息生成強度影像，以壁畫彩色影像的興趣邊緣和強度影像的梯度場作為配準(zhǔn)基元，在影像剛性配準(zhǔn)基礎(chǔ)上，對每條興趣邊緣進(jìn)行優(yōu)化配準(zhǔn)，然后以優(yōu)化后邊緣的特征點為控制，構(gòu)造影像之間的非剛性變換模型，完成壁畫影像與激光掃描數(shù)據(jù)的配準(zhǔn)。針對缺失的幾何部件，該課題主要研究基于拉普拉斯算子的石質(zhì)文物點云模型骨架線提取方法、不同尺度空間曲線相似度的分析方法來進(jìn)行文物虛擬修復(fù)，提高交互式文物虛擬修復(fù)的可靠性。通過對敦煌莫高窟159號洞窟佛像的激光掃描數(shù)據(jù)（共22.4G，點云精度1 mm）和紋理數(shù)據(jù)的多次自動配準(zhǔn)實驗表明該課題在文化遺產(chǎn)高精度數(shù)字重建的效果顯著。

關(guān)鍵詞：點云配準(zhǔn) 三維重建 紋理映射 虛擬修復(fù)

Abstract：Digital heritage and archaeology have attracted a lot of attention of researchers in the world. Capturing digital representation of heritage objects can be used for the preservation， restoration， access， and scholarly study. The pipeline of 3D digitization includes 3D data capturing， 3D registration， geometric modeling and texture mapping. For capturing 3D data， we can use different methods to obtain the lidar data or imagery data from several views. The multi-views and multi-sources need to be registered and merged. Therefore， based on the curvature feature points， the three-dimensional crestlines with rich information are extracted by using the point cloud clustering method and ridge line extractiontechnology. The shapes of space curves are accurately described by merging deformation energy modeland least square matching method. In order to complete the high precision point cloud automatic registration， the spatial relationship between the space curves and the optimal selection strategy oftransformation parameters are explored. For realistic rendering， texture mapping is needed to map high resolution photos onto the geometric models. Texture reconstruction of 3D sculpture is explored by using non-rigid transformation. A method of cultural relic virtual restoration is proposed based on 3D fine model. Experiments using the laser scanning data and image data of the Buddha of DunhuangMogao grottoes 159 cave （22.4 G totally， the accuracy of point clouds with 1 mm）. Multiple automatic registration and texture mapping experiments show that our methods are able to reconstruct the cultural heritage with high precision.

Key Words：Point clouds registration；3D reconstruction；Virtual restoration；Texture mapping

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