“Tomás Saraceno has, for the first time, scanned, reconstructed and reimagined spiders’ weaved spatial habitats, in a unique artistic and bioacoustics experience that uses groundbreaking methods and is expanding the horizons of scientific research.”
(Dr.Peter Jäger, Head of Arachnology, Senckenberg Research Institute)
The frames of these videos have been created during the collaboration between Tomás Saraceno and realized by the Photogrammetric Institute at TU-Darmstadt: Lasersupported “tomography”, following the idea of Tomás Saraceno: Two cameras have been applied, (Canon EOS 5D Mark II / Canon TS-E 90mm Lens (tilt-Shift)) with a distance of 147 cm to the laser layer, and 20 cm to each other. 110 pairs of stereoscopic – photogrammetric pictures have been analyzed at for the final web.
“Rare are the artists who have published papers with scientists because the science they had to feed on was too limited! To extend the frontier of art, Tómas first had to push the frontier of spider science.”
(Bruno Latour, excerpt from GLOBALE: Reset Modernity!, 2016)
Tomás Saraceno. Semi-social musical instrument Small Magellanic Cloud: built by Cyrtophora citricola (2014). Time-lapse video, 1’12’’. In collaboration with the Istituto Italiano di Tecnologia.
“But by now, I knew Tomás a bit better and that he never gave up. When Tomas asked for the next meeting and showed me together with Adrian the first results I was astonished. You could clearly see and differentiate single threads, and even better an entire 3-dimensional rotation model of the web could be performed by the computer. Since then it was still hard work for Tomas, especially – as always – the last ten percent of a perfect job takes more time than anything else before. For me as scientist the job was done: Tomás and his entire team including three colleagues at the Technical University Darmstadt did for the first time a photogrammetric »scan« of a 3-dimensional spider web! But Tomás’ idea was to re-build it 16 times larger as art installation: the mega web.”
(Peter Jäger, Crazy Threads or How Art and Science worked together)
The spiders were housed in completely translucent acrylic glass in approximate dimensions of 50 x 55 x 30 cm. This opacity allowed for the laser-sheet to enter and illuminate the threads and intersections. The Perspex House with the spider web was positioned on stilts to avoid reflections. It was at the same time positioned on a turning lathe which allows the house to move with linear precision in exact locational steps. Similarly, reference points were placed on each side of the house, creating a coordinate system allowing for precise measurements through placement accuracy. The Perspex walls were coated with spray glue to make them less slippery and therefore help the spider to climb the walls. This was discussed with a chemist and arachnologist who said it was safe for the spider’s health. With this new method, a sheet laser illuminated a 5mm vertical slice of the widow’s web. Two overlayed lasers simultaneously illuminated the web from opposite directions allowing an equal distribution of light across the web section. Then precise stereo photographs were taken of the illuminated section, which appeared as a sort of constellation of points and streaks, like a slightly overexposed image of the night sky. The quality of the photos depended largely on the orientation of the web strands to the cameras. The highest resolution of the cameras was used to capture the threads. Similarly, a tilt shift objective was applied with the stereo cameras to allow for perpendicular exactitude and the best possible sharpness. The tomographic layers were then assembled into a consistent representation of the house that held the spider’s complicated web. The laser covered a section of about 5 mm, so it took 110 sections or slices to rebuild the web three-dimensionally. You can imagine it like a long loaf of sliced bread, but in this case we had to bake it slice by slice to get the loaf. Each of the 110 pairs of stereophotos were analyzed and assembled at the Technische Universität in Darmstadt.
The capturing of the web was not 100% realized. There were some small gaps between the slices where the threads could not be recognized by the photos. So to complete the web Studio Tomás Saraceno first ran a software script that recognized the gaps, the unconnected spider silk threads, and then automatically filled them in by combining the nearest open lines to each other. This method was tested and discarded because it varied too much from the real structure. After a brief discussion with structural engineers Bollinger and Grohman about the vector extension, they sent back the file with tagged problematic junctions. These junctions had not enough connecting lines pulling from different directions so that the point could °oat at a certain height – as is necessary for the coherence of any web. Four architects then followed and extended the direction of every line, closing the gaps by looking for the corresponding threads and intersections. The process described thus far took three months. As the team of architects slowly and laboriously assembled the data and larger sections were being completed, print outs were also being produced of the 3D information. Through a process called orthographic projection, this 3D information was compressed into two dimensions, creating a map of black lines, each with a corresponding number. Every intersecting point also had a number. These numbers would later be crucial for the construction. With these data sets first tests and models were made – building small sections on a large scale first, and gradually increasing in complexity. Step by step the process to actually construct the final web was slowly revealed and optimized and construction team began to reconstruct the Black Widow web on a 16:1 scale, with final dimensions of 8m x 7m x 5m.
The large cube for reconstruction of the web was built in a helicopter hangar outside of Frankfurt am Main, in a small town named Bonames. Orthographic projections of the 3D map were stapled and pasted onto both the ceiling and the floor of the cube. The maps were mirror images of each other. The 5-meter distance between the floor and the ceiling were filled with clear nylon strings, attached by hooks on both surfaces. Every intersection received a hook and had a number that was then referenced in a book. This reference book had two sets of numbers ranging from 1–7279. The numbers of the intersections and their placement on the thread were noted. Then, with the help of long rulers and measuring tape, each intersection was measured out and marked with a white tape flag. This flag would later hold the elastic node of each and every intersection. Some nylon threads held up to five different flags at different heights. Once a strip of map was placed on the floor and ceiling, the hooks were installed, the nylons placed and heights flagged. Then the pre-tied elastic nodes were placed on each flag. From here the workers followed the lines from one node to the next. Each node had always at least three lines coming from it to a next point. The rope joining the nodes was permanently attached at one end and left loosely tied at the other end so that the workers could make changes later if they made a mistake. As the web came closer to being finished, workers began tying the secure final knots. The whole team was considering how to best remove the web from Bonames and reinstall it in Stockholm. The procedure was first to tag every contact point – that is any web strand that attached directly to the floor, ceiling or wall – each surface also had its own colour, number and lettering system to make sure any strand wouldn’t get lost amid the chaos. After every point was thoroughly tagged the web was slowly and methodically removed from the wooden box in Bonames. Using large plastic sheets as ‘soft-walls’, each sheet covering an entire surface, the web was rolled up over about five days. By the end of the process, a bulging plastic form that resembled a sausage or snake was what remained to be shipped. So there it was; a 16:1 scaled Black Widow spider web made of black rope and elastic, a procedure that took at least two years all in all, rolled up in a lot of plastic, folded and tightly tied down in a large crate, with instructions for the folks in Stockholm reading “Do not feed the snake.”
Personal email to Tomás:
“Spiders are known to use many astronomical cues for navigation. Some use the position of the moon to know what direction they are walking, some use the patterns formed by polarization of light in the sky and some may even use the bright band across the sky formed by the milky way (this is not yet proven for spiders). And since these cues change position in the sky relative to the spider over time, the spider must have an internal idea of how this change occurs over time i.e. an internal clock (not sure if the clock part of the story is important to you or just clouds the issue). In web building spiders the direction of gravity is also important. If you look at orb webs of e.g. the garden cross spider (araneus diadematus) they are never completely round.”
(Dr. Thomas Norgaard, University of Lund, Department of Cell and Organism Biology)
3D SPIDER WEB IN MICROGRAVITY
Objective: The objective of this experiment is to study and compare the building behavior and structure of three-dimensional spider webs between microgravity and normal gravity. The hypothesis is that three-dimensional webs will differ in weightlessness compared to Earth, because the animals can no longer use their weight and the gravitational reference for sensing the up and down directions. It is expected that not only the webs will be different, but also the building process will be affected because of the alteration in the sensory-motor patterns of the animals after insertion into microgravity, like those observed in astronauts. However, after longer exposure to weightlessness, it is expected that the spiders will adapt their building strategy to the new environmental conditions and that three-dimensional webs will be more Earth-like. However, it is possible that the asymmetries often observed between the upper and lower parts of these webs on Earth will no longer be present after adaptation to microgravity.
Method: Six specimens of spiders from three different species will be flown in small vials. At regular interval during the six-month space mission (beginning, middle, end), one or two spiders of each species will be transferred to a housing for a web to be built. The web will then be scanned for three-dimensional analysis. An on-board laser-supported tomography method will be used to record successive pairs of image planes. The images will be compressed and downlinked to Earth for a complete photogrammetric analysis of each thread end nodes. This will allow a digital reconstruction of the space web in 3D. Post-flight analysis of web samples for evaluation of thread diameter and stress-strain characteristics will also be performed. Expected Result: Understanding the three-dimensional structure and building behavior of spider webs and the role of the environment in their design and robustness addresses questions in arachnology concerning the evolution of webs, prey capture behavior, foraging theory and plasticity in behavior. This research also has numerous applications in various scientific fields such as chemistry, sensory physiology, ecology, engineering, architecture, and art.