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Fitting a 36,000 lb Polymer Glass Dome at the Georgia Aquarium for its New Shark Tank

By plagreca

How we managed to capture complex 3D measurements of a shark tank in only one day

dome measurements in 3D Disto software

Reynolds Polymer Technology, Inc., an acrylic specialist company based out of Colorado, faced the challenge of precisely measuring, documenting and communicating the production and installation of a custom shark tank window in the Georgia Aquarium’s expansion project. In order to do so, the precision cast-in-place concrete rebates needed to be measured in a 3-dimensional grid from a set of opposing arches – a daunting task considering the safety of the aquarium’s visitors being a liability. Sure, the rebates could have been measured by drawing a complex grid and measuring points with a tape measure. But this 35,000 lb (15,875 kg) acrylic viewing window required a 1/4” (6mm) site tolerance. If incorrectly measured, the space between the acrylic window and the concrete rebate could be too small or too large. If too small, thermal movement could fracture the window due to insufficient expansion and contraction allowances. If too large, the engineers would need to re-assess the variance for potential sealant issues, causing costly remedial work on site. The window had to fit, and the measurements had to be quick, cost effective and extremely precise.

The window had to fit, and the measurements had to be quick, cost effective and extremely precise.

The concrete rebates had two opposing arches, one horizontal at 300” (7,820 mm) long and the other vertical at 480” (12,190 mm) long. Obtaining an accurate 3-dimensional grid, precise enough to manufacture the viewing window to tolerance, would have taken days while offering measurements exceeding the manufacturing tolerances. The use of a standard tape measure can easily decrease accuracy of up to ½” (12.7 mm) over 33ft (10m) due to sag, temperature, and twist of the tape. By using a tape measure, the contractor would have added at least another ½” (12.7 mm) to the existing tolerance. This would have created significant fitment issues with the window.

Doem CAD file

Dome Installation

Reynolds Polymer selected the Leica 3D Disto to accurately measure the rebates expertly fabricated and poured by Brasfield and Gorrie. The 3D Disto measured to within 1/16” (1.58 mm) accuracy by projecting the image it saw on the accompanying wireless touchscreen tablet. The robotic feature of the 3D Disto allowed it to shoot all required points from the opposing concrete rebate arches within an hour.

The measurements were then loaded in a file within 15 minutes and directly emailed from the jobsite to the product engineer in Colorado.


dome measurements in 3D Disto softwaredome measurements in 3D Disto software

Here, the engineer was able to overlay the 3D measurements into his CAD program. The process was both fast and highly accurate, and gave confidence to Reynolds Polymer that the window would fit exactly as needed. The custom acrylic window was lifted through a special framed opening in the roof of the Georgia Aquarium and placed onto the concrete rebates, where it fit with precision and within tolerance. With this process, the Georgia Aquarium, Brasfield & Gorrie and Reynolds Polymer have provided an exceptional viewing window to the shark exhibit without concern for project delays or cost overruns. Prefabricated or assembled building products, whether they be the acrylic window at the Georgia Aquarium or granite countertops for residential kitchens, create challenges to ensure that the components fit into the site-built frames and irregular spaces of partially built structures. Highly accurate site measurements, especially for these expensive custom fabrications, ensure these puzzle pieces fit together well and without costly rework or damage. Regardless of large or small tolerances, the assurance of the 3D Disto accuracy eliminates guesswork and costly errors and reduces time used to compensate for inaccuracies.

Installed Dome