A System of Digital-Botanic Architecture
Looking to historical precedents in Louis Sullivan's System of Architectural Ornament (1924) and to botanic inspiration derived from the TumbleTruss Project, the author aims to explain how visual biomimetics and digital production can present ways to conceive, visualize, generate, draw and model physical forms from natural elements such as shells, seeds, plants, rocks, etc. In particular, the author explains how designs "grown" in plant-generating software can be deployed in other software and built as stereolithography (STL) models to illustrate a new system of architectural and sculptural design and production.
Article Frontispiece. Top left: Façade, Louis Sullivan's Merchant's National Bank, 1914, Grinnell, Iowa, U.S.A. The inspirational source for the experimental, digital application of principles from Sullivan's System of Architectural Ornament with visual biomimetics for growing architectural forms over a geometric frame. The frame (top right), determined from Sullivan's underlying geometries, then supported the digital growth of leaves, pods and geometries in the software Xfrog, resulting in the two TumbleTruss Project architectures below.
The creative reality of form lies within a continuous series emanating from a single primal life-impulse seeking and finding manifold expression in form. Life itself is thus manifested. . . .
—Louis H. Sullivan, A System of Architectural Ornament[1]
From its inception in 1995, the TumbleTruss Project has derived structure and form from native and invasive plants in the area around Santa Fe, New Mexico. The project name derives from tumble in tumbleweed and truss (the structural principle based on triangulation, notably used in bridge construction), suggesting that a TumbleTruss is an irregular, sometimes botanically inspired sculptural, architectural and/or graphic work imbued with undulating structure and surfaces. The ongoing project's physical and digital models draw upon D'Arcy Thompson [2] as a precursor-guide helping to unfold ways of extracting principles of growth formation from plants as well as Karl Blossfeldt's and Etienne-Jules Marey's photographs suggesting methods for mining graphic information [3,4]. For this work I often take firsthand observations of plant life, along with microscopy images of their cells, as well as isolated elements of form or behavioral information from X-rays, diagrams, drawings, photographs, scans and direct field observations as starting points for computer drawings and 3D models. My intention has been (and is) to create experimental architectural and sculptural constructions that live in both digital and analog worlds and that, when seen sequentially, reference the forms from which they were generated (Fig. 1). Such forms become a kind of lexicon or guide to potential compounded forms, usually beginning as a series of graphic icons (digital seeds) that then provides me with a conceptual idea-generator for developing irregularly shaped structures and undulating surfaces for both architectural and sculptural exploration.
More specifically, the project has looked to tumbleweeds (Salsola kali), an invasive plant considered a pest, whose extraordinary system of structure, interlocking barbs, and bracing creates a botanic globe (a weed ball). This networked filigree of barbs and branches enables it to withstand the impact of bouncing and rolling over miles of windblown travel—the tumbleweed's evolutionary tactic for dispersing seeds.
Studying this natural structure as a globular truss, a structural ball, I slowly initiated a loose process of form and structure imitation, leading to a series of mimetic and then mimetically evolving structural models (Fig. 2) in an attempt to define a system or strategy for design based on the tumbleweed's curving branches and interlinking barbs (similar to those in Velcro) that could be realized as physical, digital and stereolithography (STL) or Thermojet (solid object—printed) models.
Along with this development of irregular structures, I have simultaneously built a series of corresponding digital surfaces with both sculptural and architectural potential. This work has been exhibited and published and used as the basis for the master classes that I teach in the Genetic Architecture program at the International University of Catalunya's school of architecture. The work may be seen in my recent books and on-line [5].
In 2000 my ongoing investigation turned to the electronic generation of plantlike forms in which biomimetic extrapolations from plant branching, leaf forms, pods and seeds are used to examine a series of actual, if general, architectural and sculptural elements—connectors, clusters, containers, branching support systems and interlinking parts. I have developed a hypothesis for this segment of the TumbleTruss Project in conjunction with teaching graduate students digital visualization and botanic architecture using the software Rhinoceros (Rhino) [6], as well as with lectures on and discussions of my reinterpretation of Louis Sullivan's System of Architectural Ornament (1924) [7]. This hypothesis for growing architectural elements involves digitally hybridizing new images based on Sullivan's System and seeking ways to create individual, yet successive, elements of a developing design (a form-lexicon, as in Fig. 1) as well as growth procedures (or, very loosely, rules) in ways similar to Christopher Alexander's Pattern Language[8]. Refocusing Sullivan's morphogenic techniques on a few botanic qualities while determining parameters within which they would function diverts us from his focus on architectural ornament to mine on architectural surfaces and structures. Through this refocusing, a new lexicon can emerge and be used as the underpinning for drawing and growing experimental [End Page 15] forms in Xfrog, a botanic generating software [9]. The resulting digital growths can then be exported to Rhino and 3D Studio MAX for further scaling, detailing, drawing and final rendering.
Row 1. Tumbleweed (Salsola kali)—plant in final life stage (dried for seed dispersal). Row 2. Physical and digital structures based on, or built with, tumbleweeds for experiments with irregular truss structures and barb connectors. Row 3. Irregular, undulating, linear truss built with physical tumbleweed branches. Row 4. Xfrog-generated visual biomimetic "plant" forms based on tumbleweeds. Row 5. Xfrog-grown structural barb clusters as structural connectors. Row 6. Xfrog-grown structure abstracted from tumbleweed growth (last 3 images with glass membranes).
Botanic, Infinite Truss
Consider the tumbleweed as a dynamic truss—like a triangulated truss bridge but in the shape of a ball [10]. In its mature state, the dried and rolling weed is a botanic globe of interlocking stems, stalks, leaves, barbs and seeds. The plant's interior structure can effectively be seen as a 3D system of linking, strutlike branches, continually engaging and disengaging as the weed rolls along the ground. This rolling, bouncing and shifting creates moments of structural thrust and stress. When the weed strikes ground, the potentially rupturing forces are distributed through compression and tension networks created by the interlinking barbs and branches, dissipating force through the dense core; otherwise, continual rolling and repeated, shattering impact would fracture the brittle weed at a critical life-cycle point. Interestingly, the dead weed is responsible for seed dispersal and hence its species's propagation, and its structural integrity is complete only after death assures the plant's readiness for mobility by drying its branches, leaves and barbs into one of nature's Brillo pads, all of which takes place while the seeds are maturing. Thus the dried, springy tumbleweed is not merely a dead vegetal pest, commonly blowing across highways in the western U.S.A., but also an organism fulfilling the final stage of its evolutionary life cycle in death. The physical plant (less its root system) has become a traveling exodesic armature for sprinkling the landscape with thousands of seeds [11].
Continually transferring stress by means of various truss configurations interlocked with Velcro-like barbs, the rolling weed presents itself as a model for biomimetic investigation—for the TumbleTruss Project, the dead weed leads to structural mimesis serving as the basis for ideas extrapolated into sculpture and architecture. Rolling and shifting, the tumbleweed redistributes its own structural weight, while the wind's force against it, in conjunction with stresses from the points of ground impact, create near-infinite combinations of temporarily engaged truss networks, all held within its globular shape—a dynamic, progressive cycle of interlocking, curvilinear struts that for the architect suggests ideas of irregular truss networks for roof, wall and shell constructions. (As an aside, the same multiplicity of barbs and frequency of branching that ensures the weed's mobile integrity—its system of shock absorbers—also prove painfully sharp to any critter thinking of a tumbleweed lunch.)
This nomadic weed, originally from Siberia, is a tumbling, mobile botanic projectile as well as a moving depositor of seeds ripe for idea harvesting. The natural truss-globe is a smart botanic growth, stimulating memes for thought. The weed's structural principles and properties—either scaled down to a nano level or scaled up to a system of composite components such as beams, links, struts, etc.—could be applied to surface and structural materials whose stresses are various and directionally shifting, while the curvature and barb connections may be conceptually articulated as a system for architecture and sculpture.
With these biomimetic observations on tumbleweeds, I hope I have illustrated how nonscientific study of natural forms can be incorporated into architecture and design visualization. I associate the biomimetic process with growing ideas (leading to forms) from which I have entered into a one-sided collaboration with idea-seeds resurrected from Louis Sullivan's physical and theoretical work. Sullivan, the pioneer of the skyscraper and the architectural theorist who coined the phrase "form follows function" [12], found inspiration in cell morphology, plant and human anatomy, engineering and science and might not protest the inspiration he has sparked in the digital architecture of the TumbleTruss Project. Nor might he protest his association with the experimental use of software intended more for 3D generation of pastoral natural forms, such as oak trees, than as a tool to investigate architectural space based on plants. As far as I know, I am among a handful of researchers seriously integrating such software, namely Xfrog, into architectural education and [End Page 16] experimental research. While many Xfrog users create gorgeous graphics and regularly post them at the Xfrog users group web site, none systematically or theoretically attempts to articulate a digital botanic architecture (or any digital architecture) using Xfrog as a co-authoring tool.
Seeding Botanic Architecture
Louis Sullivan's System of Architectural Ornament is analog, transcendentally poetic, quasi-scientific and ornamental. His System nevertheless establishes a series of steps, a recipe and formula—loosely, an algorithm—for the generation of geometric surface volumes and plantlike growth as an initial impetus toward design development that can be seen as a seed of botanic architecture. After evolving geometries or, as Sullivan says, the "development of a blank block through a series of mechanical manipulations" [13], he begins to outline a progression of physical and metaphorical steps that lead toward the growth of ornamental botanic life over the "blank block." Discussing the first seven sketches for his Plate 2, The Manipulation of the Organic (Fig. 3), he states: "Any of these forms may be changed into any of the others through a series of systematic organic changes technically known as 'morphology'" [14]. Sullivan articulates the experiments in an attempt to develop his verbal thesis into a hybrid textual/ graphic hypothesis, indicating that for him architectural form has inherent real "organic" life, not merely a metaphorical suggestion of it. He had, in fact, already laid the groundwork for such a suggestion when he began the System with a little sketch of a germinating seed followed by this text, which I call the "Cotyledon Stanzas":
Above is drawn a diagram of a typical seed with two cotyledons. The cotyledons are specialized rudimentary leaves containing a supply of nourishment sufficient for the initial stage of the development of the germ.
The Germ is the real thing; the seat of identity. Within its delicate mechanism lies the will to power: the function which is to seek and eventually to find its full expression in form.
The seat of power and the will to live constitute the simple working idea upon which all that follows is based—as to efflorescence [15].
In this Nietzschean-tinted text, Sullivan establishes growth, change, mutation and "will to power" as his transformative criteria for the development of architectural thought, which he then applies to ornament and we, by extrapolation, may apply to architectural production. Today, his instructions may be read as starting points for design instructions and can be translated, rewritten, edited and/or regrown in digital realms, in software. Sullivan's choice of efflorescence, his code word for a process of life and growth, instills botanic transformation in both a physical and metaphorical sense. He created a series of poetic, graphic/text (analog) algorithms constituting his metaphoric design-genotype that he had previously used to draw (grow) ornament whose embedded code (memes) sprouted the System, which now is capable of sprouting digital growth.
Left: Mature tumbleweed (Salsola kali) next to biomimetically derived, Xfrog-grown, virtual tumbleweed (right). Note the complex linking of barb and branches in the natural tumbleweed compared with the extrapolated and differently formed "fan-barbs" of the digital tumbleweed. The biomimetic intent was to learn from the branching and barbs, not to attempt an exact copy.
With a botanic underpinning established, Sullivan then set out to describe and illustrate how growth and generation may be applied to architectural design through the development of a series of cellular drawings (drawings we can think of as extended phenotypes), each linked to the preceding and each leading to the next—a visual progression developing his geometric and botanic form lexicons into a transformative evolutionary process that could be artistically determined and transformed while autonomously efflorescing, living, flowering through his "will to power." Furthermore, the three little "Cotyledon Stanzas" hint (the completed System is a vindication) that Sullivan's dictum, "form follows function," while willfully misread by most Modernists, was, in Sullivan's organic theory, still a living, progressive principle in which the process of design links botanic as well as biologic life with geometry (not merely reductive spatially programmatic requirements, such as floor plans), and should be historically and theoretically revisited with a view to Sullivan's intended meaning and context.
By the time of the System's drawing and printing, Sullivan was out of touch with the architectural world he had helped make modern—the forgotten and neglected master reduced from a major architect to an almost unemployed, unheard thinker and writer. The last decade of his life found him building little and then only sporadically. Yet a few of the last buildings, I speculate, provided physical armatures and metaphorical seeds that let him finally germinate his System into a masterpiece of architectural drawing, literature and theory. For me the System is the sole example of a Transcendental architectural theory with rhizomic links to Emerson, Thoreau and Whitman—and one of the few theories bridging the 19th, 20th and 21st centuries that can be translated and re-engineered digitally, losing little of its intent or focus [16]. [End Page 17]
Louis H. Sullivan, American, 1856-1924, System of Architectural Ornament, According with a Philosophy of Man's Powers: Manipulation of the Organic, 1922, graphite on Strathmore paper, 57.7 x 73.5 cm, commissioned by the Art Institute of Chicago, 1988.15.2. Note the morphological changes as procedural manipulations (potentially, digitally coded or animated) that Sullivan draws in "simple leaf-forms" (top row) and "compound leaf-forms" (second row). Third row: Sullivan transforms one "simple leaf-form" sequentially into a complex morphological growth that he labels "Plastic changes, following nature's method of liberating energy." He then further develops two of the resulting growths (drawing numbers 13 and 12) at the bottom of the drawing.
Tumbleweeds and Sullivan
The Merchant's National Bank, a 1914 American Midwestern savings bank designed by Sullivan, now provides a retrospective, 3D reading of physical forms and, in conjunction with the System, illustrates how radical his work was and is. This bank may be seen as an analog proto-generator for botanic architecture. In a sense, the façade is a built drawing whose ornament is a metaphorical fractal of Sullivan's theoretical and graphic work, which was further realized a few years later when he wrote his System. Both works, bank and System, continue stimulating us 70-plus years later by influencing design in virtual space and through CAD/CAM production. Today we can still see and think of segments of the System as germinators whose genetic expression reached one threshold in Sullivan's lifetime but whose unexpressed potential, like that in DNA, may continue to reveal itself in future growth and morphosis. In the context of the TumbleTruss Project, Sullivan's System illuminates a developmental thread for articulating static graphics as digitally grown 3D forms—serial extended phenotypes—that then help articulate qualities or attributes found in natural systems capable of being developed as experimental structures and surfaces.
While lecturing at Iowa State University in 2002, I took a side trip to visit the farm town of Grinnell, where the Merchant's National Bank stands efflorescent and in excellent, healthy condition. For my purposes here the bank need be considered only as a rectangular "blank block" whose oculus (rose window) and entrance fuse in a terra-cotta growth of geometry, vines and pods that host Sullivan's ideas as articulately as paper does his drawing. Looking at the main façade's nested expansion of geometries simultaneously colonized with plant growth, I saw the potential for a digital graft. Thinking of a phototropic shift from the z axis to the xy axis, I visualized a hypothetical growth from exterior to interior, with the façade ornament seeding horizontal branching into the bank's interior to morphologically transform the System of ornament into a system of structure (see Article Frontispiece). Situating the new growth as an interior spatial armature demonstrates a first step: I was not thinking of habitable spaces or even scales compatible with the bank but of the idea that plantlike growth creates a structure whose branches, stems and buds mark spatial nodes where a potential habitable space might later effloresce. I was thinking of reanimating Sullivan's late work by graft-hybridization with new digital slips, regrowing one or two aspects of Sullivan's system, taking his ornament and further applying some of his rules to generate new structural spaces sprouted in Xfrog and Rhino drawings, where they could be biomimetically influenced by and inherit some tumbleweed form/ structure/behavior along with some qualities of my TumbleTruss research.
One thing the Merchant's Bank makes clear is how closely Sullivan's realized work relates to the System's illustrations, drawn nearly 10 years later. The steps he drew in his System can retrospectively be seen to function as a recipe for a hierarchical form of development; yet, if the plates were manipulated into 3D cubes (something now digitally possible), penetrating and interconnecting volumes similar to the bank's exterior skin and interior space, they would more fully illustrate the 3D, botanic potential inherent in the System even as the physical, built bank historically realizes the System 's drawings materially.
Using digital methods to hybridize Sullivan's ideas with TumbleTruss-Xfrog growths, I have, for example, determined symmetrical points in the bank's terra-cotta ornament from which to begin sprouting Xfrog drawings (Fig. 4). The first segment of this digital growth is strictly balanced: a series of interlacing [End Page 18] loops or tendrils creates a symmetrical, knotlike design lifting out of a simulated façade, creating a decorative braided coil before twisting back to grow horizontal tendrils for a structural armature. Once forms are sprouted, I have tried to loosely conform and apply tumbleweed observations and Rhino modeling to Xfrog's controls—rotation, twist, screw, transformation, phototropism, curvature, etc. Moving ideas appropriated from Sullivan into software extends their capacity for generating new work while growing new ideas for me. Attaching Sullivan's System to his own creation experimentally generates new works but does not lead me to claim that I can generate Sullivan works. Nor, in experimenting with one of his architectural masterpieces, am I suggesting that such a manipulation ever take place—horror. It is rather that, as I stood in front of the bank, a certain artistic logic suggested his ornament as the generator of other forms, and consequently I initially employed the site as a seedbed for an experiment that has grown ideas and led to the generation of Xfrog drawings and models. This experimentation, however, is conceptual, never intended as an intrusion, not even hypothetically, upon a historic monument. If the physical building helped me germinate ideas and drawings, its parental responsibilities stop there.
The Hypothesis
In the merger of botanic and digital production I am seeing potentials inherent in software such as Xfrog, where digitally realized volumes mimic or simulate organic growth, making possible the application of plant simulation for architectural, volumetric shapes. Embedded in this simulation of growth is the cognitive, biological learning taking place—the growth of my thoughts manifesting itself in the resulting sculptural and architectural production. While I rely on metaphor, I also trust that my approach of growing forms from System seeds, combined with information applied from botanical observation along with TumbleTruss experiments cross-fertilized by theory articulated by Richard Dawkins (memes and extended phenotypes) [17], begins to illustrate how Sullivan's work could infect mine, and how mine could infect others, with ideas for growing digital architecture. I propose to attempt this growth process with observational botany, visual biomimetics and digital growth fused together in a design process yielding sculptural and architectural components. Yet this process is fully open to other scientific or information patterns where software integrates and fuses biological or mathematical information with geometry, growing geometrics in place of branches, but also able to algorithmically establish sub-branching, budding and flowering, for example, in the simulated architectural growth. Such procedures, I think, establish the claim that Sullivan's system harbors lifelike, genetic information. If so, then his drawings (and many drawings, by implication) are the equivalent of Jurassic amber encasing DNA (and to play this out a bit, the implications of Benjamin's "Work of Art in the Age of Mechanical Reproduction" take on new, literal life). So, if we entertain such a scenario as outlined above, a mechanical reproduction like an edition of A System of Architectural Ornament carries Sullivan's genetic seed, implanted with his pencil in the original drawing, his genetic-graphic imprint (extended phenotype), transported through space and time into new designs where it confers powers of heritance and morphing (in his sense and ours) to new work, while equally ensuring offspring. I see
Xfrog growth seeded from Sullivan's Merchant's Bank façade, followed by selected stages of growth development leading to the forms seen in Article Frontispiece.
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this process as analogous to, or at least an offshoot of, the concept that live, cultural units of transmissible information—idea-memes—can be carried through history and inherited in a genelike system of cultural and physical transmission. In this case the idea-memes are architectural messengers—live, tumbling ideas reseeding inert media and rolling on as new botanic architecture.
Conclusion: The Tumbletruss as Sullivanesque Growth
Sullivan's System also suggests possibilities of a second kind: biomimetic process and generation. Through ways of morphing 2D drawing into 3D volumes, examining interstitial spaces and reapplying as well as reassembling construction procedures, unseen structural contexts and new forms can be manifested in digital visualizations. The biomimetic and digital visualization process presents a set of possibilities different from those of purely digital generation and suggests an a priori research agenda aimed at mining the System's existing morphologies and extended phenotypes for different spatial ends. The spatial fusion inherent, if embryonic, in Sullivan's drawings can now be interpreted with new insight for digital translation and reformatted into diagrammatic shape/volume vocabularies for recombination, thus further extending the System's mimetic value. The grammar of Sullivan's System, parsed in light of current and emerging technologies or analyzed as analog-hybrid spaces, provides a reading of Sullivan's original intentions while still generating possibilities for new patterns of visualization, which in turn create new test fields for a botanic or a digital-botanic architecture.
While investigations into the physical form of tumbleweeds has propelled the TumbleTruss Project for a decade and resulted in complex analog and digital warped and curved surfaces and structures, my working with Sullivan's System has initially (and temporarily) inflicted a predictable but unwanted complication—the element of symmetry. In a sort of hair shirt of self-imposed discipline, I have initially maintained the rigid symmetry consistent with the almost universal balancing of Sullivan's ornament and only slowly broken structural regularity by introducing gradual and slight variation. In retaining the symmetry, at least initially, my thinking has been that a chance exists for the System to imprint itself more fully on the overall TumbleTruss work and that by maintaining and stimulating it to a more developed stage a new, desirable and/or useful extended phenotype (lexicon element) may emerge. I intend to learn from the imposed symmetry, document it as part of the project and then gradually break away from it and programmatically change the structure and spaces in a merger with a TumbleTruss network. For example, one aspect of such a symmetry/ asymmetry transformation can be seen in the schematic illustration of Fig. 5. When a symmetrical Xfrog drawing is
Inspired by a pinecone, Xfrog screen shots illustrate digitally grown botanic clusters as nested geometries and the spider-like frame for holding them. The two images on the bottom right show Xfrog files manipulated through Rhino and rendered in 3D Studio MAX.
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Top: Canopy for a beach plaza in Barcelona, Spain, using Xfrog-grown tree for the support column. Second row: Screen shots of the tree grown in Xfrog. Third row: Xfrog files manipulated in Rhino to transform the tree into a column and rendered as in 3D Studio MAX. Fourth row: Physical, solid mock-up, machine-built from digital files as an STL model by Laser Reproduction.
gradually given new instructions for asymmetrical growth, the once-podlike forms (nested in a second, symmetrical pentagon armature) morphologically transform into an asymmetrical prismatic or crystalline cluster with clear implications for architectural massing.
This sort of transformation, from what resembled a cluster of grapes to what resembles a stacking of prisms, again illustrates the potential for intentionally creating a morphological process with the expectation that the resulting geometries can then be architecturally or sculpturally engaged in a process of design development. Once more, I hybridize the digital drawing with information or observations from tumbleweed (or other plant) field observations and ideas seeded by the System. This process results in a conceptual fusion of Sullivan's theory with botanic information and procedures of digital and computational extension. For example, the generation of a tree in Xfrog is then developed as an architectural column or, without its trunk, as a branching structure for the support of floors grown like leaves (Fig. 6 and Color Plate B No. 2). Such a design process implicates the biomimetic hybridization of natural forms with digital morphological growth, suggesting a new way of architectural and sculptural form generation from which the seeds of A System of Digital-Botanic Architecture are emerging.
Dennis Dollens is a designer and writer based in Santa Fe, New Mexico. He teaches in the architecture school at the Universitat Internacional de Catalunya and in the design department of ELISAVA: Escola Superior de Disseny, Universitat Pompeu Fabra, (Barcelona).
