TY - CHAP A1 - Grewe, Carl Martin A1 - Zachow, Stefan T1 - Fully Automated and Highly Accurate Dense Correspondence for Facial Surfaces T2 - Computer Vision – ECCV 2016 Workshops N2 - We present a novel framework for fully automated and highly accurate determination of facial landmarks and dense correspondence, e.g. a topologically identical mesh of arbitrary resolution, across the entire surface of 3D face models. For robustness and reliability of the proposed approach, we are combining 2D landmark detectors and 3D statistical shape priors with a variational matching method. Instead of matching faces in the spatial domain only, we employ image registration to align the 2D parametrization of the facial surface to a planar template we call the Unified Facial Parameter Domain (ufpd). This allows us to simultaneously match salient photometric and geometric facial features using robust image similarity measures while reasonably constraining geometric distortion in regions with less significant features. We demonstrate the accuracy of the dense correspondence established by our framework on the BU3DFE database with 2500 facial surfaces and show, that our framework outperforms current state-of-the-art methods with respect to the fully automated location of facial landmarks. Y1 - 2016 U6 - https://doi.org/10.1007/978-3-319-48881-3_38 VL - 9914 SP - 552 EP - 568 PB - Springer International Publishing ER - TY - THES A1 - Pilz, Sven-Kristofer T1 - Multi-View Reconstruction based on Mesh Photo-Consistency Optimization KW - Multi-View Reconstruction KW - Photo-Consistency Optimization Y1 - 2016 ER - TY - JOUR A1 - Zachow, Stefan T1 - Computational Planning in Facial Surgery JF - Facial Plastic Surgery N2 - This article reflects the research of the last two decades in computational planning for cranio-maxillofacial surgery. Model-guided and computer-assisted surgery planning has tremendously developed due to ever increasing computational capabilities. Simulators for education, planning, and training of surgery are often compared with flight simulators, where maneuvers are also trained to reduce a possible risk of failure. Meanwhile, digital patient models can be derived from medical image data with astonishing accuracy and thus can serve for model surgery to derive a surgical template model that represents the envisaged result. Computerized surgical planning approaches, however, are often still explorative, meaning that a surgeon tries to find a therapeutic concept based on his or her expertise using computational tools that are mimicking real procedures. Future perspectives of an improved computerized planning may be that surgical objectives will be generated algorithmically by employing mathematical modeling, simulation, and optimization techniques. Planning systems thus act as intelligent decision support systems. However, surgeons can still use the existing tools to vary the proposed approach, but they mainly focus on how to transfer objectives into reality. Such a development may result in a paradigm shift for future surgery planning. Y1 - 2015 U6 - https://doi.org/10.1055/s-0035-1564717 VL - 31 IS - 5 SP - 446 EP - 462 ER - TY - JOUR A1 - Grewe, Carl Martin A1 - Schreiber, Lisa A1 - Zachow, Stefan T1 - Fast and Accurate Digital Morphometry of Facial Expressions JF - Facial Plastic Surgery Y1 - 2015 U6 - https://doi.org/10.1055/s-0035-1564720 VL - 31 IS - 05 SP - 431 EP - 438 PB - Thieme Medical Publishers CY - New York ER - TY - GEN A1 - Grewe, Carl Martin T1 - 3D Digital Morphology of Human Faces T2 - Anthropologie der Wahrnehmung. Marsilius-Sommerakademie Heidelberg, 14.-20. September Y1 - 2015 ER - TY - THES A1 - le Roux, Gabriel T1 - Development and Evaluation of Algorithms for 3D Facial Motion Estimation from Stereo Videos Y1 - 2017 ER - TY - THES A1 - Zänker, Martin T1 - Estimating Human Face Reflectance from Single-Shot Multiview Data Y1 - 2017 ER - TY - JOUR A1 - Grewe, Carl Martin A1 - Liu, Tuo A1 - Hildebrandt, Andrea A1 - Zachow, Stefan T1 - The Open Virtual Mirror Framework for Enfacement Illusions - Enhancing the Sense of Agency With Avatars That Imitate Facial Expressions JF - Behavior Research Methods Y1 - 2022 U6 - https://doi.org/10.3758/s13428-021-01761-9 PB - Springer ER - TY - THES A1 - Grewe, Martin T1 - An Extended 3D Morphable Face Model with Applications in Experimental Psychology N2 - Our faces and facial expressions are an important means of communication and social interaction. One goal of the behavioral sciences is to better understand how the features of the faces that we look at influence our behavior. These include static features like facial proportions or the shape and color of certain parts of a face which primarily constitute facial identity, as well as dynamic movements resulting from the activation of the mimic musculature. Experimental psychology provides an empirical approach to this endeavor. In experiments, participants are typically exposed to images or videos of realistic faces with specifically controlled features. By analysis of the reactions to such stimuli, conclusions can be drawn about the influence of facial features on the participants’ behavior. Psychologists today mostly generate face stimuli with the help of digital tools. Image editing with Photoshop is highly flexible, but also time-consuming and subjective. Using tools like Psychomorph or Fantamorph is easier and more objective, but does not allow specific control over facial features. In contrast, stimulus generation with 3D Morphable Face Models (3DMMs) offers a better balance between objectivity, ease of use, and flexibility. 3DMMs are statistical models which have been determined from 3D scans of real people’s faces and facial expressions. After these training scans have been brought into correspondence, methods like principal component analysis (PCA) can be used to determine the major modes of variation of facial shape and texture in the data. Such modes typically vary the overall facial proportions, expressions, or skin color. They can be individually controlled and flexibly combined to generate new faces and facial expressions. The plausibility of the generated faces can be ensured by having the mode combinations follow the multivariate distribution of the training data. 3DMMs have been mostly used by psychologists for the generation of stimulus images of faces with neutral expression. Static and dynamic stimuli of facial expressions are also of great interest, but generation with 3DMMs is less common. A problem is that the majority of current 3DMMs can only generate facial movements according to the six prototypic expressions of anger, disgust, fear, happiness, sadness, and surprise. More diverse or subtle expressions are often impossible. Among other reasons, this is due to the difficulty in establishing accurate correspondence in the training data. Further, the modes of most 3DMMs were created by means of PCA. These modes often lack interpretability, fail to generate facial details, and rarely provide psychologists a specific control over identity or expression features. Some 3DMMs also generate subtle artifacts that might lead to undesired effects during face perception. They are also less realistic than faces which were designed by artistic experts for recent computer games and animated movies. Last but not least, current 3DMMs have probably not yet been used for interactive experiments in virtual reality (VR) for technical reasons. Although they provide many advantages also beyond the generation of static or dynamic stimuli, the limitations of current 3DMMs have so far prevented a widespread usage in experimental psychology. The goal of this dissertation is to foster the creation and usage of 3DMMs in this context. To this end, we make three major contributions. First, we describe a matching method that establishes correspondence for 3D face scans with a very high accuracy. Unlike the most commonly used methods, it transforms the facial features into a 2D intermediate representation so that they can be aligned to a reference using image registration. We perform experiments with a large database of 3D scans of faces and facial expressions showing that our method outperforms previous approaches. Second, the 3D scans which were previously brought into correspondence are used for the creation of a 3DMM whose resolution is an order of magnitude higher than that of most existing models. We learn a variety of meaningful modes that, e.g., vary features only in specific regions of the face, or that are related to demographic factors such as ethnicity and age. Further, modes of local facial movements are established that can be flexibly combined into a large variety of expressions. We evaluate the quality of the newly created 3DMM in two experiments. Our results show its advantages over previous models, especially the higher degree of realism of dynamic stimuli of facial expressions which were created with our model. Third, we demonstrate that 3DMMs can not only be used for the generation of stimuli. We develop two experimental methods that are readily applicable in experimental psychology. Initially, we create 3D avatar faces with our 3DMM that are readily applicable in VR. They are used in a new open source framework for virtual mirror experiments on self-face perception. A study is conducted which demonstrates the advantages of the framework over previous methods. Furthermore, our 3DMM is used to create a method for improved control of facial asymmetry in existing stimulus photographs. We show that the method accounts for different dimensions of facial asymmetry and is less sensitive than previous approaches to extrinsic factors like the posture of the head. The different methods are evaluated in a study investigating the influence of facial asymmetry on ratings of attractiveness, femininity, and masculinity. The results indicate the benefits and validity of our method. KW - facial modeling KW - 3D morphable face model KW - facial analysis KW - experimental psychology Y1 - 2023 U6 - https://doi.org/10.14279/depositonce-18589 ER -