TY - CONF AB - Tactile feedback of an object’s surface enables us to discern its material properties and affordances. This understanding is used in digital fabrication processes by creating objects with high-resolution surface variations to influence a user’s tactile perception. As the design of such surface haptics commonly relies on knowledge from real-life experiences, it is unclear how to adapt this information for digital design methods. In this work, we investigate replicating the haptics of real materials. Using an existing process for capturing an object’s microgeometry, we digitize and reproduce the stable surface information of a set of 15 fabric samples. In a psychophysical experiment, we evaluate the tactile qualities of our set of original samples and their replicas. From our results, we see that direct reproduction of surface variations is able to influence different psychophysical dimensions of the tactile perception of surface textures. While the fabrication process did not preserve all properties, our approach underlines that replication of surface microgeometries benefits fabrication methods in terms of haptic perception by covering a large range of tactile variations. Moreover, by changing the surface structure of a single fabricated material, its material perception can be influenced. We conclude by proposing strategies for capturing and reproducing digitized textures to better resemble the perceived haptics of the originals. AU - Degraen, Donald AU - Piovarci, Michael AU - Bickel, Bernd AU - Kruger, Antonio ID - 10148 SN - 978-1-4503-8635-7 T2 - 34th Annual ACM Symposium TI - Capturing tactile properties of real surfaces for haptic reproduction ER - TY - JOUR AB - Volumetric light transport is a pervasive physical phenomenon, and therefore its accurate simulation is important for a broad array of disciplines. While suitable mathematical models for computing the transport are now available, obtaining the necessary material parameters needed to drive such simulations is a challenging task: direct measurements of these parameters from material samples are seldom possible. Building on the inverse scattering paradigm, we present a novel measurement approach which indirectly infers the transport parameters from extrinsic observations of multiple-scattered radiance. The novelty of the proposed approach lies in replacing structured illumination with a structured reflector bonded to the sample, and a robust fitting procedure that largely compensates for potential systematic errors in the calibration of the setup. We show the feasibility of our approach by validating simulations of complex 3D compositions of the measured materials against physical prints, using photo-polymer resins. As presented in this paper, our technique yields colorspace data suitable for accurate appearance reproduction in the area of 3D printing. Beyond that, and without fundamental changes to the basic measurement methodology, it could equally well be used to obtain spectral measurements that are useful for other application areas. AU - Elek, Oskar AU - Zhang, Ran AU - Sumin, Denis AU - Myszkowski, Karol AU - Bickel, Bernd AU - Wilkie, Alexander AU - Křivánek, Jaroslav AU - Weyrich, Tim ID - 9241 IS - 5 JF - Optics Express TI - Robust and practical measurement of volume transport parameters in solid photo-polymer materials for 3D printing VL - 29 ER - TY - JOUR AB - This paper presents a method for designing planar multistable compliant structures. Given a sequence of desired stable states and the corresponding poses of the structure, we identify the topology and geometric realization of a mechanism—consisting of bars and joints—that is able to physically reproduce the desired multistable behavior. In order to solve this problem efficiently, we build on insights from minimally rigid graph theory to identify simple but effective topologies for the mechanism. We then optimize its geometric parameters, such as joint positions and bar lengths, to obtain correct transitions between the given poses. Simultaneously, we ensure adequate stability of each pose based on an effective approximate error metric related to the elastic energy Hessian of the bars in the mechanism. As demonstrated by our results, we obtain functional multistable mechanisms of manageable complexity that can be fabricated using 3D printing. Further, we evaluated the effectiveness of our method on a large number of examples in the simulation and fabricated several physical prototypes. AU - Zhang, Ran AU - Auzinger, Thomas AU - Bickel, Bernd ID - 9376 IS - 5 JF - ACM Transactions on Graphics KW - multistability KW - mechanism KW - computational design KW - rigidity SN - 0730-0301 TI - Computational design of planar multistable compliant structures VL - 40 ER - TY - JOUR AB - We present a computational design system that assists users to model, optimize, and fabricate quad-robots with soft skins. Our system addresses the challenging task of predicting their physical behavior by fully integrating the multibody dynamics of the mechanical skeleton and the elastic behavior of the soft skin. The developed motion control strategy uses an alternating optimization scheme to avoid expensive full space time-optimization, interleaving space-time optimization for the skeleton, and frame-by-frame optimization for the full dynamics. The output are motor torques to drive the robot to achieve a user prescribed motion trajectory. We also provide a collection of convenient engineering tools and empirical manufacturing guidance to support the fabrication of the designed quad-robot. We validate the feasibility of designs generated with our system through physics simulations and with a physically-fabricated prototype. AU - Feng, Xudong AU - Liu, Jiafeng AU - Wang, Huamin AU - Yang, Yin AU - Bao, Hujun AU - Bickel, Bernd AU - Xu, Weiwei ID - 9408 IS - 6 JF - IEEE Transactions on Visualization and Computer Graphics SN - 19410506 TI - Computational design of skinned Quad-Robots VL - 27 ER - TY - JOUR AB - Photorealistic editing of head portraits is a challenging task as humans are very sensitive to inconsistencies in faces. We present an approach for high-quality intuitive editing of the camera viewpoint and scene illumination (parameterised with an environment map) in a portrait image. This requires our method to capture and control the full reflectance field of the person in the image. Most editing approaches rely on supervised learning using training data captured with setups such as light and camera stages. Such datasets are expensive to acquire, not readily available and do not capture all the rich variations of in-the-wild portrait images. In addition, most supervised approaches only focus on relighting, and do not allow camera viewpoint editing. Thus, they only capture and control a subset of the reflectance field. Recently, portrait editing has been demonstrated by operating in the generative model space of StyleGAN. While such approaches do not require direct supervision, there is a significant loss of quality when compared to the supervised approaches. In this paper, we present a method which learns from limited supervised training data. The training images only include people in a fixed neutral expression with eyes closed, without much hair or background variations. Each person is captured under 150 one-light-at-a-time conditions and under 8 camera poses. Instead of training directly in the image space, we design a supervised problem which learns transformations in the latent space of StyleGAN. This combines the best of supervised learning and generative adversarial modeling. We show that the StyleGAN prior allows for generalisation to different expressions, hairstyles and backgrounds. This produces high-quality photorealistic results for in-the-wild images and significantly outperforms existing methods. Our approach can edit the illumination and pose simultaneously, and runs at interactive rates. AU - Mallikarjun, B. R. AU - Tewari, Ayush AU - Dib, Abdallah AU - Weyrich, Tim AU - Bickel, Bernd AU - Seidel, Hans Peter AU - Pfister, Hanspeter AU - Matusik, Wojciech AU - Chevallier, Louis AU - Elgharib, Mohamed A. AU - Theobalt, Christian ID - 9819 IS - 4 JF - ACM Transactions on Graphics SN - 07300301 TI - PhotoApp: Photorealistic appearance editing of head portraits VL - 40 ER - TY - JOUR AB - Material appearance hinges on material reflectance properties but also surface geometry and illumination. The unlimited number of potential combinations between these factors makes understanding and predicting material appearance a very challenging task. In this work, we collect a large-scale dataset of perceptual ratings of appearance attributes with more than 215,680 responses for 42,120 distinct combinations of material, shape, and illumination. The goal of this dataset is twofold. First, we analyze for the first time the effects of illumination and geometry in material perception across such a large collection of varied appearances. We connect our findings to those of the literature, discussing how previous knowledge generalizes across very diverse materials, shapes, and illuminations. Second, we use the collected dataset to train a deep learning architecture for predicting perceptual attributes that correlate with human judgments. We demonstrate the consistent and robust behavior of our predictor in various challenging scenarios, which, for the first time, enables estimating perceived material attributes from general 2D images. Since our predictor relies on the final appearance in an image, it can compare appearance properties across different geometries and illumination conditions. Finally, we demonstrate several applications that use our predictor, including appearance reproduction using 3D printing, BRDF editing by integrating our predictor in a differentiable renderer, illumination design, or material recommendations for scene design. AU - Serrano, Ana AU - Chen, Bin AU - Wang, Chao AU - Piovarci, Michael AU - Seidel, Hans Peter AU - Didyk, Piotr AU - Myszkowski, Karol ID - 9820 IS - 4 JF - ACM Transactions on Graphics SN - 07300301 TI - The effect of shape and illumination on material perception: Model and applications VL - 40 ER - TY - CONF AB - The reflectance field of a face describes the reflectance properties responsible for complex lighting effects including diffuse, specular, inter-reflection and self shadowing. Most existing methods for estimating the face reflectance from a monocular image assume faces to be diffuse with very few approaches adding a specular component. This still leaves out important perceptual aspects of reflectance as higher-order global illumination effects and self-shadowing are not modeled. We present a new neural representation for face reflectance where we can estimate all components of the reflectance responsible for the final appearance from a single monocular image. Instead of modeling each component of the reflectance separately using parametric models, our neural representation allows us to generate a basis set of faces in a geometric deformation-invariant space, parameterized by the input light direction, viewpoint and face geometry. We learn to reconstruct this reflectance field of a face just from a monocular image, which can be used to render the face from any viewpoint in any light condition. Our method is trained on a light-stage training dataset, which captures 300 people illuminated with 150 light conditions from 8 viewpoints. We show that our method outperforms existing monocular reflectance reconstruction methods, in terms of photorealism due to better capturing of physical premitives, such as sub-surface scattering, specularities, self-shadows and other higher-order effects. AU - B R, Mallikarjun AU - Tewari, Ayush AU - Oh, Tae-Hyun AU - Weyrich, Tim AU - Bickel, Bernd AU - Seidel, Hans-Peter AU - Pfister, Hanspeter AU - Matusik, Wojciech AU - Elgharib, Mohamed AU - Theobalt, Christian ID - 9957 SN - 1063-6919 T2 - Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition TI - Monocular reconstruction of neural face reflectance fields ER - TY - JOUR AB - With the wider availability of full-color 3D printers, color-accurate 3D-print preparation has received increased attention. A key challenge lies in the inherent translucency of commonly used print materials that blurs out details of the color texture. Previous work tries to compensate for these scattering effects through strategic assignment of colored primary materials to printer voxels. To date, the highest-quality approach uses iterative optimization that relies on computationally expensive Monte Carlo light transport simulation to predict the surface appearance from subsurface scattering within a given print material distribution; that optimization, however, takes in the order of days on a single machine. In our work, we dramatically speed up the process by replacing the light transport simulation with a data-driven approach. Leveraging a deep neural network to predict the scattering within a highly heterogeneous medium, our method performs around two orders of magnitude faster than Monte Carlo rendering while yielding optimization results of similar quality level. The network is based on an established method from atmospheric cloud rendering, adapted to our domain and extended by a physically motivated weight sharing scheme that substantially reduces the network size. We analyze its performance in an end-to-end print preparation pipeline and compare quality and runtime to alternative approaches, and demonstrate its generalization to unseen geometry and material values. This for the first time enables full heterogenous material optimization for 3D-print preparation within time frames in the order of the actual printing time. AU - Rittig, Tobias AU - Sumin, Denis AU - Babaei, Vahid AU - Didyk, Piotr AU - Voloboy, Alexey AU - Wilkie, Alexander AU - Bickel, Bernd AU - Myszkowski, Karol AU - Weyrich, Tim AU - Křivánek, Jaroslav ID - 9547 IS - 2 JF - Computer Graphics Forum SN - 0167-7055 TI - Neural acceleration of scattering-aware color 3D printing VL - 40 ER - TY - JOUR AB - The understanding of material appearance perception is a complex problem due to interactions between material reflectance, surface geometry, and illumination. Recently, Serrano et al. collected the largest dataset to date with subjective ratings of material appearance attributes, including glossiness, metallicness, sharpness and contrast of reflections. In this work, we make use of their dataset to investigate for the first time the impact of the interactions between illumination, geometry, and eight different material categories in perceived appearance attributes. After an initial analysis, we select for further analysis the four material categories that cover the largest range for all perceptual attributes: fabric, plastic, ceramic, and metal. Using a cumulative link mixed model (CLMM) for robust regression, we discover interactions between these material categories and four representative illuminations and object geometries. We believe that our findings contribute to expanding the knowledge on material appearance perception and can be useful for many applications, such as scene design, where any particular material in a given shape can be aligned with dominant classes of illumination, so that a desired strength of appearance attributes can be achieved. AU - Chen, Bin AU - Wang, Chao AU - Piovarci, Michael AU - Seidel, Hans Peter AU - Didyk, Piotr AU - Myszkowski, Karol AU - Serrano, Ana ID - 10574 IS - 12 JF - Visual Computer SN - 0178-2789 TI - The effect of geometry and illumination on appearance perception of different material categories VL - 37 ER - TY - JOUR AB - We introduce a novel technique to automatically decompose an input object’s volume into a set of parts that can be represented by two opposite height fields. Such decomposition enables the manufacturing of individual parts using two-piece reusable rigid molds. Our decomposition strategy relies on a new energy formulation that utilizes a pre-computed signal on the mesh volume representing the accessibility for a predefined set of extraction directions. Thanks to this novel formulation, our method allows for efficient optimization of a fabrication-aware partitioning of volumes in a completely automatic way. We demonstrate the efficacy of our approach by generating valid volume partitionings for a wide range of complex objects and physically reproducing several of them. AU - Alderighi, Thomas AU - Malomo, Luigi AU - Bickel, Bernd AU - Cignoni, Paolo AU - Pietroni, Nico ID - 10184 IS - 6 JF - ACM Transactions on Graphics SN - 0730-0301 TI - Volume decomposition for two-piece rigid casting VL - 40 ER - TY - JOUR AB - Elastic bending of initially flat slender elements allows the realization and economic fabrication of intriguing curved shapes. In this work, we derive an intuitive but rigorous geometric characterization of the design space of plane elastic rods with variable stiffness. It enables designers to determine which shapes are physically viable with active bending by visual inspection alone. Building on these insights, we propose a method for efficiently designing the geometry of a flat elastic rod that realizes a target equilibrium curve, which only requires solving a linear program. We implement this method in an interactive computational design tool that gives feedback about the feasibility of a design, and computes the geometry of the structural elements necessary to realize it within an instant. The tool also offers an iterative optimization routine that improves the fabricability of a model while modifying it as little as possible. In addition, we use our geometric characterization to derive an algorithm for analyzing and recovering the stability of elastic curves that would otherwise snap out of their unstable equilibrium shapes by buckling. We show the efficacy of our approach by designing and manufacturing several physical models that are assembled from flat elements. AU - Hafner, Christian AU - Bickel, Bernd ID - 9817 IS - 4 JF - ACM Transactions on Graphics KW - Computing methodologies KW - shape modeling KW - modeling and simulation KW - theory of computation KW - computational geometry KW - mathematics of computing KW - mathematical optimization SN - 0730-0301 TI - The design space of plane elastic curves VL - 40 ER - TY - JOUR AB - Bending-active structures are able to efficiently produce complex curved shapes from flat panels. The desired deformation of the panels derives from the proper selection of their elastic properties. Optimized panels, called FlexMaps, are designed such that, once they are bent and assembled, the resulting static equilibrium configuration matches a desired input 3D shape. The FlexMaps elastic properties are controlled by locally varying spiraling geometric mesostructures, which are optimized in size and shape to match specific bending requests, namely the global curvature of the target shape. The design pipeline starts from a quad mesh representing the input 3D shape, which defines the edge size and the total amount of spirals: every quad will embed one spiral. Then, an optimization algorithm tunes the geometry of the spirals by using a simplified pre-computed rod model. This rod model is derived from a non-linear regression algorithm which approximates the non-linear behavior of solid FEM spiral models subject to hundreds of load combinations. This innovative pipeline has been applied to the project of a lightweight plywood pavilion named FlexMaps Pavilion, which is a single-layer piecewise twisted arch that fits a bounding box of 3.90x3.96x3.25 meters. This case study serves to test the applicability of this methodology at the architectural scale. The structure is validated via FE analyses and the fabrication of the full scale prototype. AU - Laccone, Francesco AU - Malomo, Luigi AU - Perez Rodriguez, Jesus AU - Pietroni, Nico AU - Ponchio, Federico AU - Bickel, Bernd AU - Cignoni, Paolo ID - 9208 IS - 9 JF - SN Applied Sciences TI - A bending-active twisted-arch plywood structure: Computational design and fabrication of the FlexMaps Pavilion VL - 2 ER - TY - JOUR AB - BACKGROUND:The introduction of image-guided methods to bypass surgery has resulted in optimized preoperative identification of the recipients and excellent patency rates. However, the recently presented methods have also been resource-consuming. In the present study, we have reported a cost-efficient planning workflow for extracranial-intracranial (EC-IC) revascularization combined with transdural indocyanine green videoangiography (tICG-VA). METHODS:We performed a retrospective review at a single tertiary referral center from 2011 to 2018. A novel software-derived workflow was applied for 25 of 92 bypass procedures during the study period. The precision and accuracy were assessed using tICG-VA identification of the cortical recipients and a comparison of the virtual and actual data. The data from a control group of 25 traditionally planned procedures were also matched. RESULTS:The intraoperative transfer time of the calculated coordinates averaged 0.8 minute (range, 0.4-1.9 minutes). The definitive recipients matched the targeted branches in 80%, and a neighboring branch was used in 16%. Our workflow led to a significant craniotomy size reduction in the study group compared with that in the control group (P = 0.005). tICG-VA was successfully applied in 19 cases. An average of 2 potential recipient arteries were identified transdurally, resulting in tailored durotomy and 3 craniotomy adjustments. Follow-up patency results were available for 49 bypass surgeries, comprising 54 grafts. The overall patency rate was 91% at a median follow-up period of 26 months. No significant difference was found in the patency rate between the study and control groups (P = 0.317). CONCLUSIONS:Our clinical results have validated the presented planning and surgical workflow and support the routine implementation of tICG-VA for recipient identification before durotomy. AU - Dodier, Philippe AU - Auzinger, Thomas AU - Mistelbauer, Gabriel AU - Wang, Wei Te AU - Ferraz-Leite, Heber AU - Gruber, Andreas AU - Marik, Wolfgang AU - Winter, Fabian AU - Fischer, Gerrit AU - Frischer, Josa M. AU - Bavinzski, Gerhard ID - 7220 IS - 2 JF - World Neurosurgery SN - 1878-8750 TI - Novel software-derived workflow in extracranial–intracranial bypass surgery validated by transdural indocyanine green videoangiography VL - 134 ER - TY - JOUR AB - The combined resection of skull-infiltrating tumours and immediate cranioplastic reconstruction predominantly relies on freehand-moulded solutions. Techniques that enable this procedure to be performed easily in routine clinical practice would be useful. A cadaveric study was developed in which a new software tool was used to perform single-stage reconstructions with prefabricated implants after the resection of skull-infiltrating pathologies. A novel 3D visualization and interaction framework was developed to create 10 virtual craniotomies in five cadaveric specimens. Polyether ether ketone (PEEK) implants were manufactured according to the bone defects. The image-guided craniotomy was reconstructed with PEEK and compared to polymethyl methacrylate (PMMA). Navigational accuracy and surgical precision were assessed. The PEEK workflow resulted in up to 10-fold shorter reconstruction times than the standard technique. Surgical precision was reflected by the mean 1.1 ± 0.29 mm distance between the virtual and real craniotomy, with submillimetre precision in 50%. Assessment of the global offset between virtual and actual craniotomy revealed an average shift of 4.5 ± 3.6 mm. The results validated the ‘elective single-stage cranioplasty’ technique as a state-of-the-art virtual planning method and surgical workflow. This patient-tailored workflow could significantly reduce surgical times compared to the traditional, intraoperative acrylic moulding method and may be an option for the reconstruction of bone defects in the craniofacial region. AU - Dodier, Philippe AU - Winter, Fabian AU - Auzinger, Thomas AU - Mistelbauer, Gabriel AU - Frischer, Josa M. AU - Wang, Wei Te AU - Mallouhi, Ammar AU - Marik, Wolfgang AU - Wolfsberger, Stefan AU - Reissig, Lukas AU - Hammadi, Firas AU - Matula, Christian AU - Baumann, Arnulf AU - Bavinzski, Gerhard ID - 7218 IS - 8 JF - International Journal of Oral and Maxillofacial Surgery SN - 0901-5027 TI - Single-stage bone resection and cranioplastic reconstruction: Comparison of a novel software-derived PEEK workflow with the standard reconstructive method VL - 49 ER - TY - THES AB - Form versus function is a long-standing debate in various design-related fields, such as architecture as well as graphic and industrial design. A good design that balances form and function often requires considerable human effort and collaboration among experts from different professional fields. Computational design tools provide a new paradigm for designing functional objects. In computational design, form and function are represented as mathematical quantities, with the help of numerical and combinatorial algorithms, they can assist even novice users in designing versatile models that exhibit their desired functionality. This thesis presents three disparate research studies on the computational design of functional objects: The appearance of 3d print—we optimize the volumetric material distribution for faithfully replicating colored surface texture in 3d printing; the dynamic motion of mechanical structures— our design system helps the novice user to retarget various mechanical templates with different functionality to complex 3d shapes; and a more abstract functionality, multistability—our algorithm automatically generates models that exhibit multiple stable target poses. For each of these cases, our computational design tools not only ensure the functionality of the results but also permit the user aesthetic freedom over the form. Moreover, fabrication constraints were taken into account, which allow for the immediate creation of physical realization via 3D printing or laser cutting. AU - Zhang, Ran ID - 8386 SN - 2663-337X TI - Structure-aware computational design and its application to 3D printable volume scattering, mechanism, and multistability ER - TY - THES AB - Fabrication of curved shells plays an important role in modern design, industry, and science. Among their remarkable properties are, for example, aesthetics of organic shapes, ability to evenly distribute loads, or efficient flow separation. They find applications across vast length scales ranging from sky-scraper architecture to microscopic devices. But, at the same time, the design of curved shells and their manufacturing process pose a variety of challenges. In this thesis, they are addressed from several perspectives. In particular, this thesis presents approaches based on the transformation of initially flat sheets into the target curved surfaces. This involves problems of interactive design of shells with nontrivial mechanical constraints, inverse design of complex structural materials, and data-driven modeling of delicate and time-dependent physical properties. At the same time, two newly-developed self-morphing mechanisms targeting flat-to-curved transformation are presented. In architecture, doubly curved surfaces can be realized as cold bent glass panelizations. Originally flat glass panels are bent into frames and remain stressed. This is a cost-efficient fabrication approach compared to hot bending, when glass panels are shaped plastically. However such constructions are prone to breaking during bending, and it is highly nontrivial to navigate the design space, keeping the panels fabricable and aesthetically pleasing at the same time. We introduce an interactive design system for cold bent glass façades, while previously even offline optimization for such scenarios has not been sufficiently developed. Our method is based on a deep learning approach providing quick and high precision estimation of glass panel shape and stress while handling the shape multimodality. Fabrication of smaller objects of scales below 1 m, can also greatly benefit from shaping originally flat sheets. In this respect, we designed new self-morphing shell mechanisms transforming from an initial flat state to a doubly curved state with high precision and detail. Our so-called CurveUps demonstrate the encodement of the geometric information into the shell. Furthermore, we explored the frontiers of programmable materials and showed how temporal information can additionally be encoded into a flat shell. This allows prescribing deformation sequences for doubly curved surfaces and, thus, facilitates self-collision avoidance enabling complex shapes and functionalities otherwise impossible. Both of these methods include inverse design tools keeping the user in the design loop. AU - Guseinov, Ruslan ID - 8366 KW - computer-aided design KW - shape modeling KW - self-morphing KW - mechanical engineering SN - 2663-337X TI - Computational design of curved thin shells: From glass façades to programmable matter ER - TY - JOUR AB - Cold bent glass is a promising and cost-efficient method for realizing doubly curved glass facades. They are produced by attaching planar glass sheets to curved frames and require keeping the occurring stress within safe limits. However, it is very challenging to navigate the design space of cold bent glass panels due to the fragility of the material, which impedes the form-finding for practically feasible and aesthetically pleasing cold bent glass facades. We propose an interactive, data-driven approach for designing cold bent glass facades that can be seamlessly integrated into a typical architectural design pipeline. Our method allows non-expert users to interactively edit a parametric surface while providing real-time feedback on the deformed shape and maximum stress of cold bent glass panels. Designs are automatically refined to minimize several fairness criteria while maximal stresses are kept within glass limits. We achieve interactive frame rates by using a differentiable Mixture Density Network trained from more than a million simulations. Given a curved boundary, our regression model is capable of handling multistable configurations and accurately predicting the equilibrium shape of the panel and its corresponding maximal stress. We show predictions are highly accurate and validate our results with a physical realization of a cold bent glass surface. AU - Gavriil, Konstantinos AU - Guseinov, Ruslan AU - Perez Rodriguez, Jesus AU - Pellis, Davide AU - Henderson, Paul M AU - Rist, Florian AU - Pottmann, Helmut AU - Bickel, Bernd ID - 8562 IS - 6 JF - ACM Transactions on Graphics SN - 0730-0301 TI - Computational design of cold bent glass façades VL - 39 ER - TY - DATA AB - Supplementary movies showing the following sequences for spatio-temporarily programmed shells: input geometry and actuation time landscape; comparison of morphing processes from a camera recording and a simulation; final actuated shape. AU - Guseinov, Ruslan ID - 8375 TI - Supplementary data for "Computational design of curved thin shells: from glass façades to programmable matter" ER - TY - DATA AU - Guseinov, Ruslan ID - 8761 TI - Supplementary data for "Computational design of cold bent glass façades" ER - TY - JOUR AB - Advances in shape-morphing materials, such as hydrogels, shape-memory polymers and light-responsive polymers have enabled prescribing self-directed deformations of initially flat geometries. However, most proposed solutions evolve towards a target geometry without considering time-dependent actuation paths. To achieve more complex geometries and avoid self-collisions, it is critical to encode a spatial and temporal shape evolution within the initially flat shell. Recent realizations of time-dependent morphing are limited to the actuation of few, discrete hinges and cannot form doubly curved surfaces. Here, we demonstrate a method for encoding temporal shape evolution in architected shells that assume complex shapes and doubly curved geometries. The shells are non-periodic tessellations of pre-stressed contractile unit cells that soften in water at rates prescribed locally by mesostructure geometry. The ensuing midplane contraction is coupled to the formation of encoded curvatures. We propose an inverse design tool based on a data-driven model for unit cells’ temporal responses. AU - Guseinov, Ruslan AU - McMahan, Connor AU - Perez Rodriguez, Jesus AU - Daraio, Chiara AU - Bickel, Bernd ID - 7262 JF - Nature Communications KW - Design KW - Synthesis and processing KW - Mechanical engineering KW - Polymers SN - 2041-1723 TI - Programming temporal morphing of self-actuated shells VL - 11 ER -