Recent advances in 3D printing of biomaterials.

3D Printing promises to produce complex biomedical devices according to computer design using patient-specific anatomical data. Since its initial use as pre-surgical visualization models and tooling molds, 3D Printing has slowly evolved to create one-of-a-kind devices, implants, scaffolds for tissue engineering, diagnostic platforms, and drug delivery systems. Fueled by the recent explosion in public interest and access to affordable printers, there is renewed interest to combine stem cells with custom 3D scaffolds for personalized regenerative medicine. Before 3D Printing can be used routinely for the regeneration of complex tissues (e.g. bone, cartilage, muscles, vessels, nerves in the craniomaxillofacial complex), and complex organs with intricate 3D microarchitecture (e.g. liver, lymphoid organs), several technological limitations must be addressed. In this review, the major materials and technology advances within the last five years for each of the common 3D Printing technologies (Three Dimensional Printing, Fused Deposition Modeling, Selective Laser Sintering, Stereolithography, and 3D Plotting/Direct-Write/Bioprinting) are described. Examples are highlighted to illustrate progress of each technology in tissue engineering, and key limitations are identified to motivate future research and advance this fascinating field of advanced manufacturing

Copyright Protection of 3D Digitized Sculptures by Use of Haptic Device for Adding Local-Imperceptible Bumps

This research aims to improve some approaches for protecting digitized 3D models of cultural heritage objects such as the approach shown in the authors\u27 previous research on this topic. This technique can be used to protect works of art such as 3D models of sculptures, pottery, and 3D digital characters for animated film and gaming. It can also be used to preserve architectural heritage. In the research presented here adding protection to the scanned 3D model of the original sculpture was achieved using the digital sculpting technique with a haptic device. The original 3D model and the model with added protection were after that printed at the 3D printer, and then such 3D printed models were scanned. In order to measure the thickness of added protection, the original 3D model and the model with added protection were compared. Also, two scanned models of the printed sculptures were compared to define the amount of added material. The thickness of the added protection is up to 2 mm, whereas the highest difference detected between a matching scan of the original sculpture (or protected 3D model) and a scan of its printed version (or scan of the protected printed version) is about 1 mm

DeepSketch2Face: A Deep Learning Based Sketching System for 3D Face and Caricature Modeling

Face modeling has been paid much attention in the field of visual computing. There exist many scenarios, including cartoon characters, avatars for social media, 3D face caricatures as well as face-related art and design, where low-cost interactive face modeling is a popular approach especially among amateur users. In this paper, we propose a deep learning based sketching system for 3D face and caricature modeling. This system has a labor-efficient sketching interface, that allows the user to draw freehand imprecise yet expressive 2D lines representing the contours of facial features. A novel CNN based deep regression network is designed for inferring 3D face models from 2D sketches. Our network fuses both CNN and shape based features of the input sketch, and has two independent branches of fully connected layers generating independent subsets of coefficients for a bilinear face representation. Our system also supports gesture based interactions for users to further manipulate initial face models. Both user studies and numerical results indicate that our sketching system can help users create face models quickly and effectively. A significantly expanded face database with diverse identities, expressions and levels of exaggeration is constructed to promote further research and evaluation of face modeling techniques.Comment: 12 pages, 16 figures, to appear in SIGGRAPH 201

Heritage Reproduction in the Age of High-Resolution Scanning:A Critical Evaluation of Digital Infilling Methods for Historic Preservation

High-definition digital scanning has established itself as a useful tool for documenting cultural heritage in the twenty-first century. Proponents of surveying technology are hailing the use of digital fact-based 3D models as valuable tools for recording, analyzing and safeguarding items of cultural importance. Methods for digitally filling holes have not yet been considered through the lens of historic preservation. No modeling technique is error-free and understanding how heritage professionals are addressing lacunae is vital for understanding digital heritage objects resulting from 3D scanning hardware. Frameworks exist for working with scanned data, but they define general principles for a broad range of applications and do not provide any guidelines or strategies of how to comply with them practically. This thesis is a comparative evaluation of current practices of in-filling digital lacunae that attempts to establish which methods are best suited to the following historic preservation practices: documentation, Interpretation graphics, Long-term monitoring, digital restoration, physical fabrication

Investigating user preferences in utilizing a 2D paper or 3D sketch based interface for creating 3D virtual models

Computer modelling of 2D drawings is becoming increasingly popular in modern design as can be witnessed in the shift of modern computer modelling applications from software requiring specialised training to ones targeted for the general consumer market. Despite this, traditional sketching is still prevalent in design, particularly so in the early design stages. Thus, research trends in computer-aided modelling focus on the the development of sketch based interfaces that are as natural as possible. In this report, we present a hybrid sketch based interface which allows the user to make draw sketches using offline as well as online sketching modalities, displaying the 3D models in an immersive setup, thus linking the object interaction possible through immersive modelling to the flexibility allowed by paper-based sketching. The interface was evaluated in a user study which shows that such a hybrid system can be considered as having pragmatic and hedonic value.peer-reviewe

Strokes2Surface: Recovering Curve Networks From 4D Architectural Design Sketches

We present Strokes2Surface, an offline geometry reconstruction pipeline that recovers well-connected curve networks from imprecise 4D sketches to bridge concept design and digital modeling stages in architectural design. The input to our pipeline consists of 3D strokes' polyline vertices and their timestamps as the 4th dimension, along with additional metadata recorded throughout sketching. Inspired by architectural sketching practices, our pipeline combines a classifier and two clustering models to achieve its goal. First, with a set of extracted hand-engineered features from the sketch, the classifier recognizes the type of individual strokes between those depicting boundaries (Shape strokes) and those depicting enclosed areas (Scribble strokes). Next, the two clustering models parse strokes of each type into distinct groups, each representing an individual edge or face of the intended architectural object. Curve networks are then formed through topology recovery of consolidated Shape clusters and surfaced using Scribble clusters guiding the cycle discovery. Our evaluation is threefold: We confirm the usability of the Strokes2Surface pipeline in architectural design use cases via a user study, we validate our choice of features via statistical analysis and ablation studies on our collected dataset, and we compare our outputs against a range of reconstructions computed using alternative methods.Comment: 15 pages, 14 figure

Versatility And Customization Of Portable Cmm In Reverse Engineering A

Reverse engineering is the technique of gathering scientific knowledge about a part by physically examining it. In the computer aided manufacturing world this is referred to as Part to CAD conversion, where the geometry of physical objects are being captured as Digital 3-D CAD Data. This is vital not only to produce drawing of parts for which no CAD data exists, but also is frequently being used to produce better designs. The industry professionals to achieve this are frequently using Coordinate Measuring Machine [CMM] among other tools. The purpose of this thesis is to demonstrate the versatility of portable CMM as a Reverse Engineering Tool through application experiments aimed at industrial and non-industrial solutions. The thesis also researches in to the feasibility of customization options through experimentations focused on reverse engineering. Focusing further on Reverse Engineering applications, some of the interesting digitizing and CAD techniques are demonstrated and compared

An innovative digital workflow to design, build and manage bamboo structures

At current rates, the building industry is the major contributor to gas emissions and energy consumption in the world, placing unprecedented pressure to find alternative and sustainable construction materials, particularly in regions where urbanization and population growth are expected to rise. Coincidentally, bamboo culms are a sustainable and abundant resource with the potential to be used as a structural element in those regions, however, their organic nature and inherent incompatibility with modern design and construction procedures have hampered their formal utilization. This article presents the details of an innovative workflow based on the philosophy that the quality and reliability of bamboo structures can be computationally managed through the digitization of individual structural bamboo elements. The workflow relies on reverse-engineering processes that integrate and make bamboo culms compatible with modern data-management platforms such as Building Information Modelling. A case study based on a reconstruction project of bamboo houses in Lombok, Indonesia is presented to illustrate the proposed workflow. This work showed that digitization and management are not just to represent shapes and information regarding bamboo culms through computer software, but can also control the quality, sustainability, and structural behavior of a bamboo structure during its entire service life

Photogrammetric measurement of 3D freeform millimetre-sized objects with micro features: an experimental validation of the close-range camera calibration model for narrow angles of view

The measurement of millimetre and micro-scale features is performed by high-cost systems based on technologies with narrow working ranges to accurately control the position of the sensors. Photogrammetry would lower the costs of 3D inspection of micro-features and would be applicable to the inspection of non-removable micro parts of large objects too. Unfortunately, the behaviour of photogrammetry is not known when photogrammetry is applied to micro-features. In this paper, the authors address these issues towards the application of digital closerange photogrammetry (DCRP) to the micro-scale, taking into account that in literature there are research papers stating that an angle of view (AOV) around 10° is the lower limit to the application of the traditional pinhole close-range calibration model (CRCM), which is the basis of DCRP. At first a general calibration procedure is introduced, with the aid of an open-source software library, to calibrate narrow AOV cameras with the CRCM. Subsequently the procedure is validated using a reflex camera with a 60mm macro lens, equipped with extension tubes (20 and 32mm) achieving magnification of up to 2 times approximately, to verify literature findings with experimental photogrammetric 3D measurements of millimetresized objects with micro-features. The limitation experienced by the laser printing technology, used to produce the bi-dimensional pattern on common paper, has been overcome using an accurate pattern manufactured with a photolithographic process. The results of the experimental activity prove that the CRCM is valid for AOVs down to 3.4° and that DCRP results are comparable with the results of existing and more expensive commercial techniques.Percoco, G.; Sánchez Salmerón, AJ. (2015). Photogrammetric measurement of 3D freeform millimetre-sized objects with micro features: an experimental validation of the close-range camera calibration model for narrow angles of view. Measurement Science and Technology. 26(9):1-9. doi:10.1088/0957-0233/26/9/095203S19269Mitchell, H. L., Kniest, H. T., & Won‐Jin, O. (1999). Digital Photogrammetry and Microscope Photographs. The Photogrammetric Record, 16(94), 695-704. doi:10.1111/0031-868x.00148Chen, Z., Liao, H., & Zhang, X. (2014). Telecentric stereo micro-vision system: Calibration method and experiments. Optics and Lasers in Engineering, 57, 82-92. doi:10.1016/j.optlaseng.2014.01.021Stamatopoulos, C., & Fraser, C. S. (2011). Calibration of long focal length cameras in close range photogrammetry. The Photogrammetric Record, 26(135), 339-360. doi:10.1111/j.1477-9730.2011.00648.xYang, X., & Fang, S. (2014). Effect of field of view on the accuracy of camera calibration. Optik, 125(2), 844-849. doi:10.1016/j.ijleo.2013.07.089Strobl, K. H., Sepp, W., & Hirzinger, G. (2009). On the issue of camera calibration with narrow angular field of view. 2009 IEEE/RSJ International Conference on Intelligent Robots and Systems. doi:10.1109/iros.2009.5354776Ricolfe-Viala, C., & Sanchez-Salmeron, A.-J. (2010). Lens distortion models evaluation. Applied Optics, 49(30), 5914. doi:10.1364/ao.49.005914Ricolfe-Viala, C., Sanchez-Salmeron, A.-J., & Valera, A. (2013). Efficient Lens Distortion Correction for Decoupling in Calibration of Wide Angle Lens Cameras. IEEE Sensors Journal, 13(2), 854-863. doi:10.1109/jsen.2012.2229704Zhang, Z. (2000). A flexible new technique for camera calibration. IEEE Transactions on Pattern Analysis and Machine Intelligence, 22(11), 1330-1334. doi:10.1109/34.888718Percoco, G., Lavecchia, F., & Salmerón, A. J. S. (2015). Preliminary Study on the 3D Digitization of Millimeter Scale Products by Means of Photogrammetry. Procedia CIRP, 33, 257-262. doi:10.1016/j.procir.2015.06.046Ricolfe-Viala, C., & Sanchez-Salmeron, A.-J. (2011). Camera calibration under optimal conditions. Optics Express, 19(11), 10769. doi:10.1364/oe.19.010769Guidi, G. (2013). Metrological characterization of 3D imaging devices. Videometrics, Range Imaging, and Applications XII; and Automated Visual Inspection. doi:10.1117/12.2021037Herráez, J., Martínez-Llario, J., Coll, E., Rodríguez, J., & Martin, M. T. (2013). Design and calibration of a 3D modeling system by videogrammetry. Measurement Science and Technology, 24(3), 035001. doi:10.1088/0957-0233/24/3/03500