engineering should not have such problems, the design process is by definition .... Abbott, D., AutoCAD: Secrets Every User Should Know Wiley Publishing Inc., ...
“Computational Civil Engineering 2010”, International Symposium Iasi, Romania, May 28, 2010
CAD Software as a Tool in Design Paul Mutic 1, Silivan Moldovan2 and Ioana Moldovan3 1
Faculty of Architecture and Urban Planning, Technical University of Cluj-Napoca, Romania Faculty of Architecture and Urban Planning, Technical University of Cluj-Napoca, Romania 3 Faculty of Civil Engineering, Technical University of Cluj-Napoca, Romania
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Summary The competition among the big producers of software programs is maintained through the evolution of programs that answer any complex problems or the ones that give solutions for any new features needed to be introduced or, often, the creation of large databases that would contain standardized building components. Unfortunately, the designers from different areas are attracted by these new facilities, but they don’t use them at their full potential. These databases introduced in designing programs together with the new features could be a disadvantage to the professionalism. We must be aware that these programs are tools for drawing and nothing more. They have to ease and help us detail our intellectual work, but not do it for ourselves. The effect of superficial design of such programs is dangerous and the results, unfortunately, are visible everywhere throughout our country. This article aims at an awareness that regards what computer aided design should be and not what it has become. Computer, all together with special programs, must be the element throughout the designer explains his project better, which helps him study better solutions and not a tool to design faster, obviously in a more shallow way. This is the never ending struggle between quantity and quality. Architecture and engineering should not have such problems, the design process is by definition a meticulous process based on intellectual work which should be not be altered by. KEYWORDS: design, CAD, tool.
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1. INTRODUCTION In the year 2010 the computers are a necessary tool in every field of work. Every office must have at least one. In the construction area the computers are basically the modern tool for design. Engineers and Architects are relying on sophisticated and expensive software to make calculations vital for their fields of work. The computer is a relatively new tool in the architectural world but is becoming a reliable and indispensable one. In our days there is a multitude of CAD software that offers different kinds of help, based on the field of interest. The CAD software is able to help on matters of mathematical equations to landscape architecture, urban planning and beyond. The main problem with this kind of software is that the designer has to master the program in order to achieve a good result. Its very easy to fall on the other side and let the software to control the drafter, but then the result is nothing more than cooking after a recipe, no creativity is involved. The creativity, the utility and viability have to be the main objectives in the design process, the computer is there only for help, to help the drafter to decide certain matters, or to ease the design process and mathematical calculations. In order to understand such problems it is necessary to understand how the software works, how is programmed to help the user. The paper is referring to one of the first CAD software used in design. At first it was developed just to replace the actual hand drawing but the technology made it to evolve into the 3rd dimension.
2. CAD COMPUTER AIDED DRAFTING CAD Computer aided drafting is the general term used for the whole range of software used for technical design. They are found in a wide range and specialties: Automotive and Transportation; Engineering & Construction; Architecture & Urban Planning; Utilities and telecommunications; Education; Manufacturing; Topography; Government database. They come in different sizes, produced by different software companies and with different database packaging. The most notorious of them all is AutoCAD.
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This program is a myth and the AutoCAD series started as software made for mechanical design, but it has been used also by engineers, architects. In time Autodesk, the company which made these software added databases for other design areas. This is the software that opened new horizons in this field. Initially, such programs offered a simple geometric design based on poly-lines, lines, arcs of circles and curves defined by points. During several years they developed, and more importantly have channeled on specific areas. In our days the CAD software is able to perform from simple 2D drawings to complex 3D virtual models, grouped by materials, layers and textures, each with its own proprieties. Al those CAD software stand at the base of 3D virtual reality and are the key component into building virtual models. The advantages are very clear. The collaboration between different areas covered in a project can be done faster, easier in a virtual environment that does not put lives in danger and allows the drafter to verify and modify every little aspect for a building. Another advantage is that the software encourages team work allowing more users to design at the same model making the design process for larger projects easier to control and supervise. Each office usually has certain design standards used for projects. These can be implemented in all projects and is not necessary to draw them each time a new project begins. Also encourages team work, exchanging drawings between users being easier and clearer. Those standards can be sent to other collaborators, which can directly implement them in their work file providing a certain graphic look for all the final prints. This file sets the project layout from line type, line scale, line print dimension, drawing scale, print colors, hatches, dimension lines, dimension font, dimension size and units, and many other settings which define the needed graphical approach for the project.
3. VECTORIAL DRAWING It is imperative that all CAD users know the difference between vector and raster drawings because of the way each type of file format can be used. The vectorial drawing is based on points that contain information and are linked between them. The raster drawing is basically composed from pixels and it is actually a picture. Both raster and vector images can be manipulated. Because raster images are made of pixels they are easy to stretch, manipulate, change the colors, remove items from it, but you cant easily change the geometry. For this action you need talent, skills and a steady hand, and most of all a raster drawing has only two dimensions. The raster drawing uses the simplest technique of drawing. Vector drawings are done in two dimensions and in three dimensions. Vector drawings are actually lines and planes all defined by points called vertexes. Every
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element in a vector drawing is drawn in space, having X, Y and Z coordinates. This means you can rotate very easy the drawing in 3d, and see all the geometrical forms drawn in virtual space. All CAD software is based on this type of file. Also the difference in file size between those two models is huge. The first vector file format was called DXF. This format is still employed in our days in order to export files from one type of software to another. It is used due to the simplicity of storing the drawing information. DWG file format is the newer and smarter file format. It stores more information than his little brother but it is able to store different proprieties in different fields of interest. This file contains also information about printing options such as line types, color, thickness and more attributes used to produce the final prints for the developed project. Also another advantage is the faster saving for the DWG file. Given the fact that we have presented the technical details and operating methods for CAD file types it is important to talk about another advantage named XREF. This process allows links between the work file and other files without modifying them. For example we have an architectural project for the engineering department. They use this method to build specialty drawings without modifying the architecture file. Also they can use their standard graphic features and specialty items without problems. Due to this procedure the file produced by them is smaller in size than in case weve had the architecture in the same file. Using complex elements such as blocks or AEC / BIM objects (Fig. 1.) it is another strong point for CAD software. Those elements are designed by the software producer, a specific contractor or even by the drafter. The main purpose is to create objects libraries for elements such as doors, windows, furniture, HVAC elements, metal structural elements, and so on, that can be used in multiple projects and are detailed as the final product. The objects dimensions can be modified from a project to another but the proprieties remain the same.
Figure 1. Sample of BIM objects
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3D modeling is based to a large extent on such information. This way the computer can provide using a model accurately drawn, all the lists of quantities, much closer to reality, saving hours of work if some changes of the solution are required. Unfortunately, in order to build a 3D model correctly, the user must know the project to the smallest detail. This is possible only near the completion of the design process when they have already drawn the final plans. These steps are covered seldom and especially in large, atypical, expensive projects where every technical solution should be checked. The main benefit of designing with computer is that the model could change very easily due to different technical solutions or economical matters and the designer does not have to draw again the whole project. The software is built in a way that allows changes of the drawing scale and line thickness. There are some directions for this field of use like Wireless technology, Modelbased as a 3D model (now being used only as a base for working drawings), fullsize virtual buildings that clients may visit, a software payment feature including pay as you use method, and further more. We have deliberately shown the process of how a set of drawings is produced. Certainly, techniques have changed from manual drafting to computer generated drafting or CAD programs, but the process of building construction has not changed. The changes in building construction are not a result of CAD design, but rather from changes in building technology.
4. CONCLUSIONS The struggle for supremacy between these programs offers us today some complex design programs, but also some exclusivist ones. The most useful approach is that designers from different specialties should work all employing the same program. The disadvantage is appears when one of the specialty designers uses a different CAD program which is not 100% compatible with the one used by the rest of them. Such situations create mismatches between the design or mismatches between different specialties. Also because of the desire to be the best, CAD software manufacturers are hiring teams of developers to work on the databases that contain the objects employed in the process of design. The bad side is that the majority of those who work for such libraries of objects have no training creativity or design and this can easily be seen because in some cases, working with those objects can be harmful (Fig. 2.). On the other hand, these libraries are designed for large projects, where it is impossible to make a detailed drawing of each component and normally the work is done using typical and characteristic sections, the responsible of the project is
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following the project as a whole ensemble. Even if these databases for developing and controlling large projects are good or helpful, they are harmful to young designers, which tend to use them in any project, without entirely controlling its settings. This leads to monotony in the aesthetic details and also to a poor quality of the design process. The attention to detail is overlooked and even forgotten and a good example is that of students from technical universities. The students are founding their skills on these specialized programs, but they are not mastering them, and then they get to the final years with gaps in knowledge from the primary years, which are putting them in difficulty.
Figure 2. 3D model of a building created with objects from the softwares library
The efforts made by the software manufacturers are impressive, but a warning signal need to be set, regarding the quality of the projects designed with these programs. They tend to become increasingly sophisticated in order to meet the needs dictated by our creativity, but also they are more difficult to master, often controlling the designer.
References 1. Abbott, D., AutoCAD: Secrets Every User Should Know Wiley Publishing Inc., ISBN 978-00470-10993-9, Indianapolis, 2007. 2. Wakita, O., Linde, R., The Professional Practice of Architectural Working Drawings, John Wiley&Sons, Inc., ISBN: 0-471-39540-4, New York, 2003. 3. Styles, K., Bichard, A., Working Drawings Handbook, Architectural Press, ISBN: 0-7506-6372-3, Oxford, 2004.
