The Analysis of 3D-Modeling Technology - Research Proposal Example

3D MODELLING TECHNOLOGY Abstract The simple wireframe technique developed in the 1960s was replaced by a better alternative in the form of surface modelling. However, surface modelling has limitations as it cannot provide designers with a much better view of the models they are creating. Moreover, calculation of mass, volumes, and centroids are difficult and time-consuming. Due to need for a more innovative approach, solid modelling was developed by Ari Requicha & Herb Voelker in 1973. Solid modelling enables three dimensional representations of geometric shapes and creation of more complex objects by combining primitives. Unlike 2D models, 3D models allow designers to see the real shape of an object thus accuracy is ensured. More importantly, computation of the object’s physical properties is more convenient and the relationship between parts is easily established. 3D model designers can choose from manual or semi-automatic modelling and perform object manipulation in various ways. The 3D modelling processes include polygon manipulation, creation of curves and surfaces using NURBS, extrusion of splines and patching, sculpting or direct manipulation of vertices and polygons, and combining primitives to generate complex objects. Commercial and non-commercial 3D modelling tools include Blender, XSI, 3ds Studio Max, Milkshape 3D, Maya, Wavefront, Lightwave, TrueSpace, and the latest AutoCad versions. 3D modelling can achieve much more if there is a more intuitive computer interface such as touch screen devices that can directly and accurately manipulate objects. More importantly, 3D model designers should take advantage of the realistic and time-efficient approach being offered by image-based modelling. 1. Introduction Application of 3D modelling can be traced back in the early 1970s with the advent of solid modelling technique. 3D models are 3D wireframes that can be manipulated in various ways. It allows accurate representation of real-life objects and creation of more complex models. However, very few understand the real nature of 3D modelling, how it works, the difference between 2D and 3D or the variations between surface and solid models, and the limitations of current 3D modelling software. The following sections discuss the history of 3D modelling and its advantage over the traditional surface modelling system. It also include discussion on solid modelling technique, meshing and rendering objects, manual and automatic 3D modelling, and limitations of 3D modelling tools today. 2. Methodology 3D modelling technology is a very popular innovation and acquiring detailed information about it is more convenient compared to other non-popular subjects. The method used to gather the vital information required for this research paper is online research and review of relevant literatures. Online books and journals provide this paper with updated details regarding 3D modelling technology and tools developed to further enhance its performance. The availability of online materials such as those found in Google books enable this research to include important references and review other relevant literatures written specifically for the subject. These and other online materials made it possible to outline the research in a more detailed manner such as the processes involved in 3D designs and sample images of 3D modelling approaches. Moreover, it enables presentation of different modern modelling tools and its real-life applications. 3. 3D Modelling Technology 3.1 Early 3D Modelling The inability of traditional wireframe models that was popular in the late 1960s and early 1970s to provide information required to create machine parts encouraged early researchers to create 3D wireframes. Surface models were then developed and accurate definition of shapes and faces were made possible. 3D wireframe models revolutionize the manufacturing industry in particular by enabling accurate geometry and production of precision parts (Waguespack & Jahraus 2009, p.21). Unlike wireframe models that uses geometric primitives; surface models are produced using surface primitives such as plane, fillet, offset, Bezier, and B-Spline surfaces (Alavala 2008, p.126). The ability to represent shapes defined by several set surfaces led to several applications such as designs, movies, and games. The 1987 computer-graphics film “Tron” was developed using this technology (Eastman et al. 2008, p.26). However, although surface modelling is very useful in designing parts for CNC machines, surface modellers often find it difficult to calculate volumes, mass, and centroids since it is designed to create watertight surfaces (Waguespack & Jahraus 2009, p.21). Moreover, the use of surface models are only limited to image creation and they are not capable of complex shapes production (Eastman et al. 2008, p.26). For this reason, solid modelling techniques were developed separately by Ian Brain at Cambridge University, Bruce Baumgart at Standford, and Ari Requicha and Herb Voelcker at the University of Rocherster in 1973 to enable representation of watertight surfaces as solid objects consist of different faces rather than mere surfaces (Eastman et al. 2008, p.26). Solid modelling generally joins together or subtracting 3D geometric shapes to form a more complex model such as combining primitives to produce composite solids (Wilson & Williams 2001, p.247). 3.2 Advantage of 3D over 2D Presenting an object in three dimensional form enable designers to see its real shape and form thus design is more accurate. Moreover, 3D models are more understandable thus presenting ideas with other people is easy and requires no significant effort (Omura 2007, p.559). On the other hand, two dimensional objects are often not clear enough to enable visualization and analysis of object. Three dimensional models offer a global view of the object structure thus minimizing errors in design (Kamrani & Nasr 2006, p.101). For instance, 3D solid modelling is widely used in engineering graphics because it allows easy creation and manipulation of 3D models in real-time. Moreover, computations of physical properties and visualization of model parts in relation to other parts is more convenient and efficient (Lieu & Sorby 2008, p.27). 3.3 Solid and Shell/Boundary Modelling Solid modelling is generally a set of principles being use for mathematical and computerized modelling of three dimensional objects and as mentioned earlier; it is developed in the 1970s for informational completeness of mechanical geometric shapes that is not possible with surface modelling. Some important principles behind solid modelling are the fact the any re-construction of real physical object must be valid and correct. Similarly, any representation should unmistakably resemble the physical object including the smallest geometrical shape. This is because Requicha and Voelcker, the founding fathers of solid modelling, recognize the importance of mapping the structure of an object and represent it as a well-defined mathematical object (Farin & Hoscheck p.474). In 3D modelling, a ‘face’ is considered a topological entity of dimensionality that is geometrically associated with a surface and consists of several non-intersecting loops. These loops represent the boundaries between faces that share a particular edge or edges. A shell, which can be open or closed, is created when these connected faces forms two manifolds. A closed shell has no boundaries while an open shell has outer boundaries consist of different edges participating in a single face (Hasle et al. 2007, p.25). Figure 3.3.1 – Solid and Shell Model (UIC, 2010) 3.4 Meshing and Rendering The most common convenient way to build solid model is to mesh it with nodes and elements. However, the choice of mesh type, free or mapped, is dependent on the need of the designer. For instance, a free mesh has no restrictions particularly in patterns and element’s shapes while a mapped mesh is restricted and contains only triangular or quadrilateral elements as show below. A free mesh is therefore more realistic in terms of physical object modelling. The figure below shows the difference between free mesh and mapped mesh. Elements in a mapped meshed are notably restrained compared with free mesh elements, Figure 3.4.1 – Free and Mapped Meshes (Alavala 2009) In a node-based approach such as the above, the nodes are considered the primary controlling factor of a mesh which will form the elements when interconnected. At a later stage, the mesh can be refined by re-arranging the elements. In contrast, a region-based approach subdivides the object into several patches or regions where the mesh is produced automatically by mapping a particular region into a triangle. Figure 3.4.2 – Mesh produced by triangulation method (Alavala 2009) Creating coloured images 3D surface or solid model is called rendering and this is done from a scene with different lights (McFarlane 2000, p.293). Figure 3.4.3 – A meshed and rendered teapot (Metin Seven 2010) Rendering allows every cell in the mesh to be displayed and in computer generated 3D models rendering is being done in two ways. First, it draws scenes depicting a real-world object and second, detects collisions between these objects. Search and identification of collisions between depicted real-world objects and its virtual environment requires special algorithms and methods such as nested loops, local or segmented, and predictive techniques. Nested loop look for any occurrence of collision in object pairs while the locale or segmented technique divide the virtual world into regions of nearby space to determine which locales do not touch each other. The predictive technique on the other hand is more focus on the virtual object’s path and predicts the earliest collision occurrence (Nishio 1999, p.188). 3.5 Manual and Automatic 3D Modelling 3D modelling methods can be divided into two categories. The first category is automatic modelling where 3D models are generated without any interaction. The second category is manual or semi-automatic where 3D models are produced with manual markings of points in the model (Shumaker 2009, p.455). C-tech EVS and ISATIS provides automatic 3D modelling procedures (Fischer & Getis 2010, p.129) while manual and semi-automatic tools for 3D reconstruction include software such as Google Sketch-up, PhotoModeler, Cyclone, 3ds Max and so on (Oosterom 2008, p. 425). 3D models generated manually are often costly thus sophisticated automatic 3D modelling techniques are being develop such as laser rangefinder designed to measure outdoor environment and image sequence (Wojciechowski et al. 2006, p.118). There is also an approach developed by Abraham et al. in 2005 that uses 2 pieces of digital photograph to produce 3D models without much user intervention and expensive lasers (Abraham et al., 2005, p.715) Figure 3.5.1 – Automatic 3D modelling using Two Photographs (Kan 2010) 3.6 Modelling Processes 3.6.1 Polygonal Polygons are considered the building blocks of 3D modelling since it is the smallest renderable elements in a 3D object. Polygons are normally made-up of triangular faces which are defined by their vertices and edges (Meade & Arima 2007, p.58). Figure 3.6.1.1 – Components of a polygon (Meade & Arima 2007) A point in space, vertices allows changes to a shape by editing their position or connecting them to another vertex. The edge on the other hand is the component that connects these vertices and the area inside these connected vertices are faces that can be a tri, quad, or an n-gon. A polygonal mesh is created from a collection of connected faces as shown below (Meade & Arima 2007, p.59). Figure 3.6.1.2 – Polygonal mesh (Meade & Arima 2007) 3.6.2 NURBS NURBS are non-uniform rational B-splines commonly as geometric primitives in modern 3D modelling software. They are free-form curves and surfaces that allow accurate creation of curves and surfaces with smoother borders as shown below (Lucerna 2002, p.7). Figure 3.6.2.1 – Creation and rendering of 3D NURBS (Lucerna 2007) 3.6.3 Splines & Patches Splines are basically thin lines between points in a 3D model that a user can move, push, and pull through space. Combinations of non-uniform rational b-spline is called NURBS that can be use to modify or generate a surface. Splines can be extruded through space like the sample below. Figure 3.6.3.1 – Extruded star spline Patches are normally Bezier surfaces that originate from spline based edges. Patch modelling includes building a spline cage and adding a patch modifier. The spline cage is a network of splines that can be created using free from lines as show below (Discreet 2005, p.302). Figure 3.6.3.2- Sample spline cage (Discreet 2005) 3.6.4 Sculpt Modelling Similar to sculptors in a real world, 3D sculpt modelling handles objects like actual malleable clay. It naturally or directly manipulates vertices and polygons to form a real-world entity (Mullen 2009, p.31). Figure 3.6.4.1 – An image produced by 3D sculpting program 3D sculpt modelling is a free form modelling technique that can be use alongside other modelling techniques. Virtual sculpt modelling normally starts by identifying and picking points or vertices. When the points are identified, manipulation can be done by dragging them to form a desired shape (Kerlow 2004, p.113). The image below shows how vertices are manipulated to form a sculpted image. Figure 3.5.4.2 – 3D Sculpting through manipulation of vertices (Kerlow 2004) 3.6.5 Primitives Modelling In solid modelling, primitives are those fundamental geometric shapes such as spheres, cylinders, box or cube, and so on, that can be use to generate more complex figures (Shumaker 2009, p.515) as shown below. Figure 3.6.5.1 – Generating 3D models by combining a cubes and cylinders (Shumaker 2009). Most 3D modelling programs use primitives as building blocks. For instance, 3ds Max offers standard primitives, extended primitives, and splines that a user can use to build complex forms (Gerhard & Harper 2010, p.66). Figure 3.6.5.2 – Some of the standard primitives in 3ds Max (Gerhard & Harper 2010) 3.7 3D Modelling Tools Commercial and non-commercial 3D Modelling tools are available for modellers and 3D enthusiast such as Blender, XSI, 3D Studio Max, Milkshape 3D, and so on. Blender is free 3D modelling package with features found in commercial packages. Softimage XSI, Milkshape 3D and Discreet’s 3D Studio Max are a full featured commercial 3D modelling tools being use mostly for building content and animation in games (Junker 2006, p.248). Powerful 3D modelling tools include three or more features such as modelling, rendering, animation, and other useful functions. For instance, Wavefront Studio and Maya, Lightwave, and TrueSpace are powerful 3D tools used in 3D animation and industrial designs. Maya in particular is behind the visual effects in films like “A Bug’s Life” and “Titatic”. SoftImage3D on the other hand have been employed in many popular computer games and provide amazing animations in films such as ‘Deep Impact’ and ‘Air Force One’. 3D Modelling and game development in Windows platform often employ the superb rendering capabilities of 3D Studio Max and Lightwave (Chen 2008, p.362). For architectural and engineering purposes, the tradition AutoCad system has evolved into both 2D and 3D applications. For instance, AutoCAD 2008 offers not only 2D drafting tools but 3D modelling that also makes use of primitives objects like cones, cubes, and cylinders (Ambrosius 2007, p.2). Figure 3.7.3.1 – Drawing 3D-Solid Box in AutoCad (Omura 2009) 3.8 Limitations of 3D Modelling Applications Although computers are increasingly advancing in terms of speed and capacity, computer interfaces like keyboard and mouse are simply not adequate to accurately manipulate 3D objects. According to Massie (1998, p.1-4), 3D computer modelling can achieve much more if it has a more sensitive interface device capable of bidirectional interaction. For instance, 3D computer modelling that uses the sense of touch can greatly improve manipulation of 3D objects like a sculptor manipulating clay. Another limitation of current 3D Modelling tools is the reality that it takes considerable amount of time to model an object even if the user is very familiar with the tools. For instance, creating 3D contents for virtual reality using Maya or 3ds Max is a time consuming work thus most users prefer to work in image-based modelling where they only need to input images rather than create them. Moreover, 3D models created with such approach are more realistic compared to computer graphics modelling techniques (Hui et al, 2007, p.83). 4. Conclusion 3D modelling technology started in the 1960 with simple wireframe method. However, the limitations of such approach prompted researchers to find a better alternative in the form of surface and solid modelling. At first surfaced, modelling was an adequate solution but since it is designed for creating watertight surfaces, it does not allow easy calculation of mass, volumes, and centroids. Moreover, surface models are difficult to understand particularly for those that are not familiar with system. Eventually, researchers developed solid modelling technique that allows parts of an object to be viewed and manipulated separately. Solid 3D modelling allows even the most unfamiliar to recognize every part of the model with ease. 3D modelling revolutionized not only manufacturing industry but find great applications in films and games development. The limitations of 3D modelling are mainly due to the inability of current computer interfaces to accurately manipulate 3D objects and the significant time being consumed in creating images. Consequently, image-based modelling is being seen an alternative solution since it can produce more accurate representation of real-world objects, reduce 3D modelling time and costs significantly. 5. References Abraham A., Dote Y. & Furuhashi T. 2005, Soft computing as transdisciplinary science and technology: proceedings of the fourth IEEE International Workshop, WSTST'05, Springer, US Abrosius L., 2007, AutoCAD 2008 3D Modeling Workbook for Dummies, For Dummies, US Alavala C., 2008, Cad/Cam: Concepts And Applications, PHI Learning Pvt. Ltd., India Alavala C., 2009, Finite Element Methods: Basic Concepts and Applications, PHI Learning Pvt. Ltd, India Alley T., 2006, Exploring 3D modeling with Cinema 4D R9, Cengage Learning, US Chen J., 2008, Guide to Graphics Software Tools, Springer , Germany Discreet, 2005, Fundamentals and beyond courseware, Elsevier, US Eastman C., Teicholz P., & Sacks R., 2008, BIM handbook: a guide to building information modeling for owners, managers, designers, engineers, and contractors, John Wiley and Sons, US Farin G. & Hoschek J., 2002, Handbook of computer aided geometric design, Elsevier, Netherlands Filmshooting.com, 2010, Freeware Modelling/Sculpting Program, available at http://www.filmshooting.com/scripts/forum/viewtopic.php?f=1&t=21476&start=0 Fischer M. & Getis A., 2010, Handbook of Applied Spatial Analysis: Software Tools, Methods and Applications, Springer, Germany Gerhard M. & Harper J., 2010, Mastering Autodesk 3ds Max Design 2011, John Wiley and Sons, US Hasle G., Lie K., & Quak E., 2007, Geometric modelling, numerical simulation, and optimization: applied mathematics at SINTEF, Springer, Germany Hui K., Pan Z., Chi-kit R., 2007, Technologies for e-learning and digital entertainment: second international conference, Edutainment 2007, Hong Kong, China, June 11-13, 2007 : proceedings, Springer, Hong Kong Junker G.., 2006, Pro OGRE 3D programming, Apress, US Kan P., 2010, Automatic Image-Based 3D Head Modelling with a Parameterized Model Based on a Hierarchical Tree of Facial Textures, available at http://www.cescg.org/CESCG-2010/sites/KanPeter/ Kamrani A. & Nasr E., 2006, Rapid prototyping: theory and practice, Birkhäuser, US Kerlow I., 2004, The art of 3D computer animation and effects, John Wiley and Sons, US Liey D. & Sorby S., 2008, Visualization, modeling, and graphics for engineering design, Cengage Learning, US Lucerna S., 2002, In vivo atlas of deep brain structures: with 3D reconstructions, Springer, US McFarlane B., 2000, Modelling with AutoCAD 2000, Elsevier, UK Meade T. & Arima S., 2007, Maya 8: The Complete Reference, McGraw-Hill Professional, US Metin Seven, 2010, Swift 3D Max, available at http://www.metinseven.com/review_swift_3d_max.htm Mullen T., 2009, Mastering Blender, John Wiley and Sons, US Nishio S., 1999, Advanced multimedia content processing: first international conference ; proceedings, Springer, Germany Omura G., 2007, Mastering AutoCAD 2008 and AutoCAD LT 2008, John Wiley and Sons, US Omura G., 2009, Introducing AutoCAD 2010 and AutoCAD LT 2010, John Wiley and Sons, US Oosterom P., 2008, Advances in 3D Geoinformation systems, Springer, Germany Shumaker R., 2009, Virtual and Mixed Reality: Third International Conference, VMR 2009, Held as Part of HCI International 2009, San Diego, CA USA, July, 19-24, 2009, Proceedings, Springer, US UIC, 2010, 3D Sub-modelling, available online at http://tigger.uic.edu/depts/accc/software/ansys/html/guide_55/g-adv/GADV4.htm Waguespack C. & Jahraus L., 2009, Mastering Autodesk Inventor 2010, John Wiley and Sons, US Williams A., 2001, 3D modeling in AutoCAD: creating and using 3D models in AutoCAD 2000, 2000i, 2002, Focal Press, US Wojciechowski K, Smolka B., & Palus H., 2006, Computer vision and graphics: International conference, ICCVG 2004, Warsaw, Poland, September 2004, proceedings, Springer, Germany 6. Bibliography Lee J., Zlatanova S., & Zlatanova S., 2008, 3D geo-information sciences, Springer, Germany McNabb D., 2008, Research methods in public administration and nonprofit management: quantitative and qualitative approaches, M.E. Sharpe, US Read More