3D face imaging and reconstruction technology:a review
As the breakthrough technology of artificial intelligence(AI)in the big data era,deep learning(DL)has prompted the renewed upsurge of face technology.Powered by rapid developments of new technologies,such as three-dimensional(3D)vision measurement,image processing chips,and DL models,3D vision transformed into a key support-ing technology in Al,visual reality,etc.The studies and applications of 3D facial imaging and reconstruction technologies have achieved important breakthroughs.3D face data represent exact multidimensional facial attributes on account of rich visual information,such as texture,shape,space,etc.Moreover,3D face data shows robust changes in large occlusions,expressions,and poses and increases the difficulty of forgery attack.Therefore,3D face imaging and reconstruction effec-tively promote realistic"virtual digital human"reconstruction and rendering.In addition,these processes contribute to the improved security of the face system.In this paper,we comprehensively study the 3D face imaging technology and recon-struction models.The 3D face reconstruction methods based on DL are systematically and deeply analyzed.First,the development and innovation of 3D face imaging devices and capturing systems are discussed through a summary of public 3D face datasets.The devices and systems include consumer imaging devices(such as Kinect)and complex hybrid sys-tems that fuse active and passive 3D imaging technologies to achieve precise geometry and appearance.Moreover,3D face imaging based on new sensing technologies are introduced.Then,from the perspective of input resources,3D face recon-struction methods based on DL are categorized into monocular,multiview,video and audio reconstruction methods.3D face imaging technology introduces public classic 3D face datasets,popular 3D face imaging devices,and capturing sys-tems.Most high-quality 3D face datasets,such as BU-3DFE,FaceScape and FaceVerse,are captured through a large imaging volume with a certain number of high-resolution cameras and controlled lighting conditions.They play key roles in applications of realistic rendering,driven animation,retargeting,etc.On the other hand,novel optical devices and imag-ing modules with small size and lightweight algorithm must be innovated for tiny AI as intelligent mobile devices.For 3D face reconstruction based on DL,monocular reconstruction has become the most popular technology.The state-of-the-art 3D face reconstruction method is generally self-supervised training on large-scale 2D face databases.The difficulties encountered in 3D face reconstruction include the lack of large-scale 3D face datasets,occlusions and poses of in-the-wild 2D face images,continuous expression deformations,etc.The DL network structure is categorized into general deep convo-lutional neural network(such as ResNet,U-Net,and Autoencoder),generative adversarial networks(GANs),implicit neural representation(INR)(such as neural radiance field(NeRF)and signed distance functions(SDF)),and Trans-former.3DMM and FLAME are widely used 3D face representation models.The StyleGAN model gives excellent perfor-mance in recovering high-quality face texture.INR has achieved remarkable results in 3D scene reconstruction,and the NeRF model plays an important role in the reconstruction of accurate head avatars.The combination of NeRF with GAN shows great potential in the reconstruction of high-fidelity 3D face geometry and realistic rendering appearances.Moreover,the Transformer model,which greatly improves the breakthrough of accuracy and speed,is mainly used in audio-driven 3D face reconstruction.Through in-depth analyses,the research difficulties accompanying 3D face are summarized,and future developments are actively being discussed and explored.Although recent research has made amazing progresses,challenges on how to improve the robustness and generalization to real-world lighting,extreme expressions/poses,and how to effectively disentangle facial attributes(such as identity,expression,albedo,and specular reflectance)and recover accurate detailed geometry of facial motions(such as wrinkles).In this study,we proposed a comprehensive and system-atic review and covered classical technologies and studies on 3D face imaging and reconstruction in the last five years to pro-vide a good reference for face studies,developments,and applications.
3D face imaging3D face reconstructiondeep learning(DL)generative adversarial network(GAN)implicit neural representation(INR)