Computer Graphics World


Issue link:

Contents of this Issue


Page 19 of 51

n n n n Design Like a traveling circus, the annual SmartGe- ometry workshop and symposium moves from city to city, giving participants a chance to flex their creative muscles in a new location. Last year, it was San Francisco; this year, it was on famed Catalan architect Antoni Gaudi’s home turf: Barcelona. In 2001, the year explicitly referenced in the title of Arthur C. Clark’s futuristic yarn, SmartGeometry Group was formed. On its Internet home page, the group proclaims, “To the new generations of architects, mathematics and algorithms are becoming as natural as pen and pencil. Te activities of the SmartGeometry Group promote the emergence of a new genera- tion of digital designers and craftsmen, who are able to exploit the combination of digital and physical media. Te group’s interests range from parametric design and scripting to digital manu- facturing.” Teir mission gave rise to a series of design methods, almost as fanciful as science fiction. Tis year’s workshop exercises explored, for example, tensile membrane systems, inflated fabric volumes, and identical blocks that could be snapped into place. Translated into architec- tural and engineering concepts, they might mean rooftops and curtain walls shaped like wind-filled kites and sails, or modular pegs and posts that can be joined together to form support structures without welding. Te standard approach in computer-aided design (CAD) is to use a specialized 3D mod- eling package—for instance, Graphisoft’s ArchiCAD or Autodesk’s Revit for buildings; Dassault Systemes’ Catia, Parametric Technol- ogy’s (PTC) Pro/Engineer, or Siemens’ NX for automotive and aerospace—to produce a digi- tal replica of an idea. You decide the width of every window and door; you specify the radius of every arc. However, with computational design, you do not dictate every minute detail of your design; instead, you define the design criteria (for example, an acceptable range for width, 18 October 2010 Pictured here is a series of room-enclosure strategies explored by the SmartGeometry workshop group while studying acoustic surfaces. a desirable number of curves, with angular deviations by a certain degree), then let the software generate various permutations from which you can choose. Te recipe—a mix of scripting and modeling—often produces something unforeseen by the designers them- selves. Singing Rooms; Quiet Rooms Brady Peters knows how to make a room sing—or muffle it entirely. In his curriculum vitae, he explains his research focus: “[My] current research investigates new interfaces between acoustic science and architectural de- sign.… By investigating how architectural surfaces, such as walls, floors, and ceilings, can be designed and detailed to be acousti- cally regulating, the project aims to develop integrated design solutions for sound in architecture.” Peters is a PhD fellow at the Center for Information Technology and Architecture (CITA) and an architectural researcher with JJW Arkitekter and with Grontmij/CarlBro Engineers. He has flown in from Copen- hagen, Denmark, to lead a SmartGeometry workshop cluster (a small team of 10 to 15) devoted to manufacturing parametric acoustic surfaces. In this intense three-day experiment, the team under his tutelage set out to under- stand how the composition of a room affects resonant absorption and sound scattering. Aside from the common construction materi- als at their disposal (cardboards, foam, sheet metal, wood, and so forth), they used Bent- ley’s Generative Components (GC) software and Odeon’s acoustic analysis software. In his own work, Peters also uses custom computer programs written in Visual Basic or C#, along with Bentley’s MicroStation. “Sound waves occur at different frequen- cies—this is what we hear as low or high sounds,” Peters says. “Low sounds have much longer wavelengths than high sounds. Te material of a surface determines the amount of sound that is absorbed, [while] the geom- etry of the surface determines the direction in which it is reflected, and the size of the surface determines the size of wavelengths that it re- flects.” Explaining the guiding principles for building acoustic surfaces, Peters notes, “Wallace Sabine, a Harvard scientist, deter- mined that the reverberation time, the time it takes for sound to decay to inaudibility, is one of the most important in determining the acoustic performance of a space. His equation for determining reverberation time from the material properties is one that must be consid- ered. For determining reflections, I use a ray- tracing algorithm. Using geometry generated in CAD software and either acoustic analysis software or custom computer scripts, I can de- termine the amount of sound getting from a source to a receiver.” Using GC, acoustic surfaces workshop par- ticipants came up with various room shapes, distinguished by different degrees of enclo- sure. Based on acoustic analysis results show- ing sound-pressure levels and early decay time for each room composition, the team chose a model enclosed in an S-shape curve. Peters knew from his research that complex geometries with many edges and a variety of surface depths constructed from hard ma- terials tend to diffuse sound. By contrast, alternating wedge-shaped forms constructed from foam will absorb sound; and large, flat surfaces of concrete, metal, plywood, and oth- er hard materials will reflect sound. “Te absorbing qualities of the orange acous- tic foam created a dull space where all sound reflections were absorbed by surrounding walls,” Peters explains. “A performance gradient from Image courtesy of SmartGeometry Group and Bentley Systems.

Articles in this issue

Archives of this issue

view archives of Computer Graphics World - OCTOBER 2010