Generative Texture Maps for Animation

 

Anna Chupa

Electronic Visualization Program

Department of Art, Mississippi State University

achupa@erc.msstate.edu

 

Michael Chupa

Visualization, Analysis and Imaging Lab

Mississippi State University/NSF Engineering Research Center

 for Computational Field Simulation

chupa@erc.msstate.edu

 

Abstract

 

An aperiodic planar tiling is employed as the initial structure for texture application. A genera­tive process for texture metamorphosis is used to create variation producing two-dimensional artwork intended for printed output. Two-dimensional animations demonstrate the process for producing new textures. Expanding from this preliminary test, rules for opacity and relative depth, scale and velocity of movement will be related to geometric form and the length of time that a form is visible on screen. These are demonstrated in a series of two-dimensional anima­tions to be employed as a testbed for the development of rules in a 3D system. The first of these animations restricts the generation of new material to texture. Subsequent animations will add pictorial depth cues such as atmospheric perspective, occlusion, vertical placement, and diminishing size Modification of rules is based on aesthetic selection. [1] The artist is the creator of the system and the selector. [2]

 

Motivation and Concept Development

 

Goal: Develop semi-automated computer processes to pre-visualize works for print and animation. To allow for the unifying qualities achieved through repetition while celebrating the level of complexity found in nature, we explore possibilities presented in the non-periodic tiling of a plane, generative processes for developing new textures using aesthetic selection to achieve desired results, and chance procedures in visual art and music. Artists have traditionally used rule-based systems and self-imposed limitations to create constraints that are paradoxically conducive to experimentation and discovery. The computer enables the artist to visualize multiple possible relationships before a premature commitment to one solution is made.

The apparent determinism of a computer-generated process is circumvented by aesthetic selection and mutation, whereby the artist’s hand interjects to bypass a rule for more pleasing results. A preference for asymmetry and/or aperiodicity emulates the same traits in the natural world. Non-periodicity is associated with life. Ordinarily heart and brain functions are chaotic systems, but when unique rhythms approach periodicity, the regular rhythms are a precursor to heart attacks and seizures. [3]

Instead of introducing rigidity to our process, adherence to a set of self-imposed limitations yields unanticipated results and new directions to pursue. If there are junctures where the work seems stagnant, we invite external interference. Our nine-year-old son chose the p2 (parent 2) textures for the sixth generation and placed selection in a numbered box. A predominance of red is evident on the outer edges of the animation, indicating our son’s preference for high saturation. Other external contributions arise from a collaboration with Digital Imaging students. Three p2 textures come from this direction. [4]

Although two, three, four and five-fold symmetries suggest order and control, the actual process of creating the patterns manually is more like automatic writing or glossolalia. This part of the process is a result of direct physical action; selecting and photographing texture sources in the physical world, scanning and manipulating imagery in paint software, then creating seamless tiles, submitting them to multiple transformations and combining these in layers to obtain greater levels of complexity. The resulting work is a ground that is densely filled with textures derived from original photographic sources.

Historical sources for preferring compressed space, intricate surface, horror vacui and valenced imagery include medieval Celtic manuscripts and reliquaries,[5] Kongo minkisi [6,] and Fon bocio,[7] Art Brut,[8] Visionary art, [9, 10] and ultra-Baroque Mexican art,[11] As different as they may be in structure, media and cultural context; these art forms share a common aesthetic impetus of revelation and concealment,[12] sensuous surface and spiritual efficacy for the creator and the participating culture.

Characteristic descriptions of ornament in Western Classical art assume that the surface pattern is superfluous to the utility of the object to which it is being applied. Wong, et. al. define ornament as the “aesthetic enrichment of the surfaces of man-made objects in ways not directly contributing to their functional utility.” [13] A question is raised whether or not the works can be considered truly ornamental when the underlying principle or use is spiritual salvation or communion with God as in the case the aforementioned Celtic texts and Kongo minkisi.

In these examples as in my work, meaning is contained within the labyrinthine surface. The belief in the spiritual efficacy of the illuminated word is evidenced by the unorthodox ways the manuscripts were used. Notably, “the seventh-century Book of Durrow, valued as a holy relic, was used in medieval times as a cure for sick cows, by dipping it in water and giving the water to cows to drink.” [14]


Fon (Republic of Benin) and Kongo (Zaire) artist-priests create bocio and minkisi as objects of personal empowerment. These power objects are assembled with a variety of layered materials each alluding to medicine, healing, patron spirits and the dead.[15,16] Empowered with these forces, the bocio/minkisi counter danger and hostility, promoting well-being in times of stress, [17] and healing psychologically induced illnesses. “The sheer intricacy of texture and detail in many minkisi [and in bocio] contributed to ngitukulu, ‘astonishment,’ in the mind of the beholder, suggesting the presence of something extraordinary.” [18] The “intentional addition and piling up of forms… serve to invoke and sustain” spiritual power and presence.[19]

Two digital collages At the Gates 1,[20] and Brain Cell. [21] make direct reference to Kongo minkisi and Fon bocio In these works the central pictorial forms are more dominant than the surrounding borders which act as enclosures or binders of emotion, much in the way that cords, knotwork and chains, bind the powerful forces contained within the minkisi and bocio. At the Gates 1 activates forces for self-healing, using baby shoes from the 1950s dolls of my childhood in combination with fragments of the inner ear, a symbol of balance as well as the healing of a gradual hearing loss. A fetal skeleton stands as guardian to the gates and as protector of children.

Photographically captured details and close-ups of the flowers and foods that decorate a St. Joseph’s Day altar [22] and the assemblages of pottery shards, broken tile, marble, found objects and cement that recreate the Holy Land in miniature garden shrines, are recombined in tilings in my more recent work for a traveling exhibition entitled Saints Among Us. Three digital collages submitted for Generative Art 99 were created using altar and shrine details as source material for the textures.

The initial tilings in Penrose 1, Penrose 2 and St. Therese [23] conform to rules developed by Roger Penrose for filling a plane with a pair of tiles, commonly known by John Conway's [24] description as kites and darts. Penrose 1 shows the resulting repetitions of pattern groupings that occur in an aperiodic tiling that follows rules for placing the tiles. St. Therese and Penrose 2 utilize some of the pattern groupings of kites and darts to create symmetrical works. These consciously break the Penrose rules for tiling a plane, leaving negative spaces to be filled with other textures derived from the same source material.

 

Process

Animation (video)

A tiling of 394 pieces uses the infinite star pattern, one of two “Penrose universes with perfect pentagonal symmetry ” as a template.[25] Each piece is numbered so a reference point exists to establish a list of mates and their offspring. A potential mating pair consists of a kite and a dart which intersect at a vertex but share no edges. Although more than one possible mate may exist for a given tile piece, only one mate may be selected. Mating does not occur across generations. The first texture is a dart. Two possibilities exist for potential mates, I selected kite number 7. As soon as dart (1) is at 100% opacity in the animation, it begins to blink, increasing in contrast and brightness, then returning to its original state until the mate is visible at 100% opacity. Both tiles blink until children (5 and 8) are born.

Children must share an edge with at least one parent and intersect a vertex of the other parent. In this example, each of two children share an edge with both parents. One is a kite and one is a dart; hence they are fraternal twins, each inheriting 50% from tile 1 and 50% from tile 7. Children are unmasked in a linear direction starting from the point of line of intersection with each parent and going outward. As soon as they are fully visible, children begin to blink in search of mates.

Mates consist of a p1 and p2 group, where p1 always traces heritage back to the original pair (tiles 1, 7). P2 is generated spontaneously as soon as an eligible p1 emerges at full opacity. P2 does not share any of the genetic material of p1 but introduces a new texture to the process, contributing to textural diversity. The selection of p2 textures allows some room for using chance procedures. There are three possible texture inheritance patterns:

            Offspring abuts p1, abuts p2 = 50% p1, 50% p2

            Offspring abuts p1, intersects p2 at vertex = 75% p1, 25% p2

            Offspring intersects p1, abuts p2 = 25% p1, 75% p2.

By the 13th generation, all possible variations and outcomes are evident. Six p1s are unable to find an eligible mate. (I call these bachelors). One mating pair remains childless, while the maximum number of children possible (3) is generated from another pair. Two sets of parents have twins. Five sets have a single child each, 3 sets have two children each and 3 p1s encounter the outer edge, where a mate is theoretically possible but lies outside the range defined by the 394 tiles in the template.

The animation test sequence covers 7 generations in 60 seconds. In seven generations, there are no instances of childlessness from a mating pair, and no instances of triple births from one pair. There are four instances of bachelors, an five instances of twins. These variations affect the timing and duration of blinking behaviors.

 

Animation Score

The audio for the animation sequence was rendered using Csound [26] coupled with a Perl script used to generate the score file, using both deterministic and aleatory techniques. Many of the textured tile “births” are cued by particular audio events, signaled by bell-like tones. However, a specific bell tone event includes random selections from a Phrygian mode, with the third and sixth removed. This restricted tonal palette provided the desired amount of consonance to the bell tones, and served to provide a contrast to the other audio elements. In addition, the specific time used to cue a particular event was perturbed slightly from the actual cue point to a time just earlier than the cue point. The perturbation’s magnitude was controlled by a random number generator.

To provide a sense of constancy in the audio track, two layers of bass tones sharing a common tonic with the bell tones were generated, as well as a track using formant synthesis. The bass tracks extend for most of the duration of the animation, while the vocal-like formant synthesis track spans the middle half of the animation. These were produced primarily using pseudo-random processes without regard to the content of the animation sequence. Several instances were generated from the Perl script, and the most interesting was chosen for rendering with the animation sequence.

 

Future Work

Clumsy Butcher

Classification of textures into categories with rules regarding inheritable traits, dominance and other content-based and aesthetically based measures of fitness. If the database that divides the textures into possible sample groups is overly crude, the results may be poor even though the rest of the generative structure is adequate. In Plato’s Phaedrus, Socrates reveals problems inherent in any classification structure. In order to better understand a complex world, the inhabitants of that world are divided into categories. Whether or not this system reveals truth or obscures it depends upon the skill of the individual responsible for its subdivision. A skilled surgeon will yield different results relative to Plato’s “Clumsy Butcher.” [27] Herein lies the problem in defining categories for my textures. Broad categories of classification based on formal design properties (Hue, Saturation and Value, Degree of Noise, i.e., contrast)), and on degrees of verisimilitude, (Figurative vs. Non-Figurative, Naturalism vs. Abstraction) do not map themselves neatly with other subjective and associative methods for manipulating content. Metaphors can be easily apprehended when the analogies between the visual object and the concept signified are logical. But the intuitive process of art making just as often produces illogical juxtapositions. More often then not, my decision making is driven by subjective and not altogether conscious concerns with content. If, for example, I assign a higher inheritance factor to a spiritual hierarchy, it is possible that an aesthetically superior option may fail to thrive because of a low spiritual rating.

 

Indeterminacy

Because serendipitous factors in art making often result in new possibilities for exploration, I want to retain a certain degree of indeterminacy in the work. A body of literature on divination systems provides possibilities for inserting chance procedures into the process. Both the Yoruba system of Ifa and the Chinese I-Ching are based on powers of two with Ifa having 256 patterns and corresponding literature and the I-Ching, 64. Rather than write my own system of divination literature, I intend to adapt Ifa to the selection of p2 textures. This choice is consistent with the visual allusions to African and African-American minkisi, bocio and gris gris.

Aesthetic precedents for the use of indeterminacy can be found in dance and music. Merce Cunningham has used “coin tossing” at various stages of a work’s creation and by so doing has been able to reach a level of understanding inaccessible to his rational will.”[28] John Cage used the I Ching to “efface his personality from the music.”[29] In Music of Changes, one of his first compositions to use indeterminacy as a means to invigorate his predetermined structures, Cage balances chance procedures with a “limited and carefully preplanned range of possibilities.”[30] In Vodun (an African religion primarily centered in Nigeria) the tension between Fate (Determinacy) and Chance (Indeterminacy) is personified in the figures of Ifa and Eshu, the latter being a trickster figure. Just as the trickster’s goal is to challenge the status quo with unpredictable and often controversial behavior, an artist’s role in research could be the contribution of unorthodox methodology. An iconoclastic tradition in the arts “means that artists are more likely to take up line of inquiry devalued by others.”[31]

While I am interested in chance processes, I am not willing to ‘efface my personality’ to the extent that the aesthetic concept is sabotaged. For the same reason, whether or not it is possible to construct an algorithmic system that emulates my priorities both aesthetic and content-based, I am unwilling to relinquish total control. The problem will be to sufficiently define ways in which chance procedures can execute influence so that the intent behind using them (i.e., to invigorate my process) can be realized. As Simon Penny notes in The Darwin Machine, the unpredictable and paradoxical energizes art while threatening the craving for closure among scientists.[32]

 

Migration to 3D Applications

A dual gender system will be imposed whereby each mate has distinctly gendered characteristics in addition to other characteristics of texture inherited from both parents. Two three-dimensional models will be used. Each model has characteristics of movement, scale, opacity, that change relative to the age of the object. Age is influenced by a lifeline defined by a tube extruded along the path of a space curve, and by the amount of time it takes for the object to cross paths three times with another object traveling on the same lifeline. These crossings of two objects (one male, one female) produce offspring. The lifelines are translucent and opacity diminishes as the traveling objects fade from view. Traits that are passed on to the offspring are the characteristics of movement and texture that blend according to rules of dominance.

Female movements transfer to female offspring, male movement traits transfer to male offspring. Variations of movement patterns for the females will be based on Messian's wholetone scales for his Music for the End of Time. Variations on the male patterns of movement will be based on an original score to be developed by Michael Chupa for the final animation.

 

Further investigations into pattern generation.

I am interested in the work being done by Wong, Zongker and Salesin towards the development of adaptive texture mapping [33] and as well in the work being done by Neyrit and Cani [34] in the reduction of apparent periodicity through the use of triangular patches for pattern based texture mapping. Although the use of kites and darts will not persist into three dimensional applications, Andrew Glassner’s work in Recreational Computer Graphics, provides a model for the creation of 3D forms to be used.[35] At the same time I am interested in adapting the aforementioned antecedents of densely packed surfaces, i.e., the pattern work of artists such as Adolf Wolfli garden shrines created by compulsive visionaries such as Joseph Zoetel, Ultra Baroque Mexican cathedrals, Minkisi, bocio and Medieval manuscript and reliquaries. All of these share a common fixation with spiritual content as the motivation for obsessive reiteration of detail. Beyond ornament, they are at their most quiet level, a locus for peaceful meditation; at their most terrifying and sublime, they become “apotropaic incantations.” [36]


1.     Ray, Thomas S. 1997. Karl Sims Aesthetic Selection http://www.hip.atr.co.jp/~ray/pubs/art/node6.html. See also Sims, Karl. Karl Sims Home Page http://www.genarts.com/karl/.

2.     Latham, William and Joblove, George. 1993. “The Applications of Evolutionary and Biological Processes to Computer Art and Animation” Proceedings of SIGGRAPH 93 (Anaheim, California, August 1–6, 1993). In Computer Graphics Proceedings, Annual Conference Series, 1993, New York: ACM SIGGRAPH. pp. 389-390

3.     Hughes, Rod J. “Clinical Applications of Melatonin” in Sleep Medicine Alert Volume IV Number 2 Washington DC: National Sleep Foundation

4.     Student contributions to textures come from Bill Andrews, Chad Anderson, Daniel Odom, Mississippi State University, Department of Art, Master of Fine Arts in Electronic Visualization Program.

5.     Nordenfalk, Carl. 1977. Celtic and Anglo-Saxon Painting New York: George Brazilier,

6.     Harris, Michael D. 1993. “Resonance, Transformation, and Rhyme: The Art of Renee Stout” in Astonishment and Power: Kongo Minkisi & the Art of Renee Stout. Washington, DC: National Museum of African Art, Smithsonian Institution. P. 134.

        During an interview with author Michael Harris, Renee Stout describes a recycling process central to the textural surface of her assemblages: “when I sweep the floor, sometimes I don’t throw it away because I like to stick some of those things into the other work. So it’s almost like each work is connected to the next one, because the by-products of the one piece might go inside of the next piece to keep the whole thing going.”

7.     Blier, Suzanne Preston. 1995. “Vodun: West African Roots of Vodou” in Sacred Arts of Haitian Vodou. Los Angeles: Regents of the University of California.

8.     Weiss, Allen S. “Nostalgia for the Absolute: Obsession and Art Brut” in Parallel Visions: Modern Artists and Outsider Art Maurice Tuchamna and Carol S. Eliel; with contributions by Barbara Freeman...et al, Los Angeles: Los Angeles County Museum of Art and Princeton University Press, 1992. pp. 282, 284. I am particularly interested in (and saddened by) the quality of obsession and intense mental anguish that informs the use of horror vacui in Carlo Zinelli’s(1916-74) and Adolph Wolfli’s (1864-1930)work.

9.     Chupa, Anna. 1998. Ave Maria Grotto http://www.erc.msstate.edu/~achupa/am/am3.html The web documents the work of Brother Joseph Zoetel, a visionary artist who created miniature replicas of the Vatican, Jerusalem and sacred shrines in the garden of a Benedictine Monastery in Culman Alabama. I have used his work as a basis for several explorations in texture. See http://www.erc.msstate.edu/~achupa/saints/holy.html for an example.

10.   Chupa, Anna, Hanger, Anne, Woodward, Kristen. 1998. Saints Among Us An Exhibition of Works Inspired by Altars and Shrines. http://www.erc.msstate.edu/~achupa/saints/

11.   Ono, Ichiro. 1995. Divine Excess: Mexican Ultra-Baroque. San Francisco: Chronicle Books. P.83. “Fused with native American sensibility while absorbing other influences from the se-trading world that collected in Mexico, the baroque style evolved and commenced to tightly pack the architecture with so much ornamentation that we could describe it as a kind of “gap-ophobia.” This is” ultra-baroque,” meaning, in other words, the baroque of the baroque.”

12.   Nooter, Mary H. 1993. Secrecy: African Art that Conceals and Reveals. New York: The Museum for African Art.

13.   Wong, Michael T., Zongker, Douglas E. and Salesin, David H. “Computer–Generated Floral Ornament.” Proceedings of SIGGRAPH 98 (Orlando, Florida, July 19–24, 1998). In Computer Graphics Proceedings, Annual Conference Series, 1998, ACM SIGGRAPH, p. 425.

14.   Miller, Liam and Musick, pat. “Celtic Calligraphy: From Penstroke to Print” in The Celtic Consciousness, Robert O'Driscoll, editor. New York: George Brazilier, Inc. p359. Miller and Musick also mention that the punishment for shedding a manuscript artist’s blood was crucifixion.

15.   Simon, Kavuna. quoted in Astonishment and Power: Kongo Minkisi and The Art of Stout., p. 21. Minkisi acquire the power of healing "by composition, conjuring, and consecration. They are composed of earths, ashes, herbs, and leaves, and relics of the dead."

16.   Blier, Suzanne Preston. 1995. “Vodun: West African Roots of Vodou” in Sacred Arts of Haitian Vodou. Los Angeles: Regents of the University of California. Pp. 73-74. Figurative bocio consist of an abstraction of the human figure, most often made of wood, covered "with a wealth of materials:" twine, shells, beads, cloth, metal, bone fragments, and feathers. These materials "individually and in combination activate the sculpture" to enlist the aid of spiritual forces in addressing the issues concerning the individual client.

17.   Ibid.

18.   MacGaffey, Wyatt Astonishment and Power: Kongo Minkisi and The Art of Renee Stout, p. 63.

19.   Brown, David H. 1993. "Thrones of the Orichas: Afro-Cuban Altars in New Jersey, New York and Havana" in African Arts. Volume XXVI, Number 4. University of California, Los Angeles. October. p 54.

20.   Chupa, Anna. 1996 At the Gates 1 is displayed on a page that provides an overview of Fon Bocio, Kongo Minkisi as they relate to similar employed in New Orleans gris gris. http://www2.msstate.edu/~amc11/achupa/vodun/conjure.html

21.   Chupa, Anna. 1996. Brain Cell. http://www2.msstate.edu/~amc11/achupa/vodun/legba.html

22.   Chupa, Anna. 1997. Saint Joseph’s Day Altars. http://www.erc.msstate.edu/~achupa/StJo/sj_stand.html.

23.   Chupa, Anna. 1998-99. Saints Among Us . http://www.erc.msstate.edu/~achupa/saints/annaWorks2_2.html

24.   Gardner, Martin. 1989. Penrose Tiles to Trapdoor Ciphers. New York: W.H. Freeman and Company. Pp. 6-7.

25.   Ibid., p. 11.

26.   Vercoe, Barry L., et. al. The Public Csound Reference Manual: Canonical Version 4.01. Eds. John Fitch, Richard Boulanger, Jean Piché, David Boothe. Copyright 1986, 1992 Massachusetts Institute of Technology Media Lab.

27. Plato’s Phaedrus. 1952. translated with Introduction and commentary by R. Hackworth. New York: The Bobbs Merrill Company, Inc. a subsidiary of Howard W. Sams & Co., Inc.

28.   Harris, Dale. 1978. “Merce Cunningham” in Contemporary Dance: An Anthology of Lectures, Interviews and Essays with Many of the Most Important Contemporary American Choreographers, Scholars and Critics. Anne Livet, ed. New York: Abbeville Press. p. 81

29.   Simms, Brian R. 1996. Music of the Twentieth Century: Style and Structure. New York: Schirmer Books, An Imprint of Simon & Schuster Macmillan. p. 346.

30.   Ibid., p. 347.

31.   Wilson, Stephen. 1996. Art as Research. San Francisco State University. http://userwww.sfsu.edu/~swilson/artist_researcher.html

32.   Penny, Simon. Penny, Simon. The Darwin Machine: Artificial Life and Art http://www.uiah.fi/bookshop/isea_proc/nextgen/penny.html

33.   Wong, Michael T., Zongker, Douglas E. and Salesin, David H. “Computer–Generated Floral Ornament.” p. 425.

34.   Neyret, Fabrice and Cani, Marie-Paule. 1999. “Pattern-Based Texturing Revisited” Proceedings of SIGGRAPH 99 (Los Angeles, California, August 8–13, 1999). In Computer Graphics Proceedings, Annual Conference Series, 1999, ACM SIGGRAPH, pp. 235-242.

35. Glassner, Andrew S. 1999. Andrew Glassner’s Notebook: Recrational Computer Graphics. San Franscico: Morgan Kaufman Publishers.

36. Weiss, Allen S. “Nostalgia for the Absolute: Obsession and Art Brut” in Parallel Visions: Modern Artists and Outsider Art. p. 284.