本文从生成式模型的视角对三维数字人技术进行梳理, 首先整体介绍生成式三维数字人的建模流 程, 分解出其中的 3 个主要步骤 (第 2 节). 然后分别介绍数字人表示方法 (第 3 节), 数字人渲染方 法 (第 4 节), 以及模型的学习方式 (第 5 节). 之后列举了数字人的一些典型应用 (第 6 节), 最后指 出现有挑战并对未来进行展望 (第 7 节). 已有一些文献对数字人的某类建模或渲染方法进行总结, 如 3DMM 模型 [4] 、人脸重建 [5] 、人体重建 [6, 7] 、三维渲染 [8, 9] 等, 与这些文献不同, 本文旨在从生成式模 型的视角对三维数字人 (人脸及人体) 技术进行全面回顾, 重点介绍基于神经网络的数字人研究方法, 梳理其技术发展趋势及典型应用场景, 让读者能够较为全面地了解数字人的生成技术. 值得注意的是, 除了人脸与人体之外, 头发、手、服饰、骨架等模型同样也属于数字人的研究范畴, 但并非本文的主要 关注对象, 相关内容将在 7.1 和 7.2 小节予以讨论.1) https://www.nlm.nih.gov/research/visible/visible human.html.2) 图 1(a) 左: "Matilda" (https://skfb.ly/6zGMG) by nicolekeane under CC Attribution License; 右: "Girl speedsculpt" (https://skfb.ly/68RCQ) by mrrobot under CC Attribution License.3) 图 1(b) 左: "Red Skull (Rigged)" (https://skfb.ly/oFo7M) by CAPTAAINR under CC Attribution License; 右:"Amazing Spider-Man 2 Movie" (https://skfb.ly/orRTo) by CGI DUDE under CC Attribution License. 4) 图 1(c) 左: Emily [1] ; 右: Obama [1] .

Research on the microscopic migration characteristics of fluids in coal measure sandstone has always been a hot spot in the evaluation of reservoir properties. In this study, taking the Yan’an Formation sandstone reservoirs in the Block A of the Ordos Basin as an example, the pore structures and fluid migration characteristics of coal-measure sandstones are systematically studied using a large number of thin sections, SEM (Scanning Electron Microscope), NMR (Nuclear Magnetic Resonance), relative permeability and water-flooding test results. The results show that the Jurassic sandstones in the target layer mainly develop lithic quartz sandstone, and the main pore types are intergranular and dissolution pores, followed by a small amount of intercrystalline pores. The surface porosity of the target sandstones mainly ranges from 7.90 to 10.79%, with an average value of 8.78%. The good correlation between porosity and permeability indicates that the target layer is a pore-type reservoir. The T2 relaxation time of the target layer is mainly distributed within 100 ms. Moreover, the reservoir of the Yan’an Formation has a high saturation of movable fluids, which is mainly distributed in 43.17–71.24%, with an average value of 56.90%. Meanwhile, samples with fractures have higher movable fluid saturations. In addition, the average irreducible water saturation of the Yan’an Formation sandstone reservoir is 35.14%, and the final oil displacement efficiency is 51.14% on average. There is a good positive correlation between the oil displacement efficiency and the co-permeability zone. As the co-permeability zone range increased from 15 to 55%, the oil displacement efficiency increased from 30 to 65%. When the cores develop fractures, they have characteristics of high permeability, high oil recovery rate, high oil displacement efficiency in the anhydrous period, low irreducible water saturation and low residual oil saturation.

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At present, the Carboniferous-Permian shale gas in the South North China Basin is still in the exploration stage, and the understanding of the microscopic pore structures, mineral composition and hydrocarbon enrichment law of the marine-continental transitional shale gas reservoirs in this area is extremely limited. In this paper, taking the Carboniferous-Permian shale gas reservoir in the South North China Basin as an example, the geological conditions of shale gas accumulation have been systematically studied using a large amount of sedimentary, logging, seismic, core, geochemical, physical property, and scanning electron microscope data. The study shows that the transitional dark shale is stable and widely distributed in the South North China Basin. Among them, the average thickness of the high-quality shale in the Taiyuan Formation is 67 m, while that of the Shanxi Formation is 56 m. Carboniferous and Permian are the main strata for the distribution of shale gas resources. Among them, the dark shale developed in the Taiyuan and Shanxi Formations has the largest thickness and the highest organic matter abundance. In addition, the organic matter types of the Upper Paleozoic coal-measure source rocks in the South North China are mainly II2-III types, and a small part of them belong to II1 types. The brittle minerals in the target shale are mainly quartz, and the content of illite is the highest among the clay minerals. Porosity is negatively correlated with clay mineral content, and positively correlated with quartz and TOC content. In addition, the permeability is negatively correlated with the organic matter content. Finally, the criteria for key indicators of the transitional shale gas reservoirs in the South North China Basin were developed.