"Swimming" in the clouds
Travis Reinke, HDS Project Manager, PBS&J, Houston, Texas
John Kammeyer, Aquatics Design Manager, PBS&J, Encinitas, California
Over the last two decades, Gunnar, Selkie and Maureen have provided millions of people with an up-close look at the often playful, sometimes lazy, pinniped lifestyle. Gunnar and Selkie are gray seals and Maureen is a California sea lion—they all live in an aquatic habitat at the National Zoo in Washington, D.C.
Their home was built in the 1970s. The critical life support systems—the mechanical equipment that keeps the water fresh and temperate—are aging and in need of upgrade. A 5,200-square-foot life support facility is housed within a three-level structure located between the exhibits. This facility processes freshwater to and from the individual pools. The water is pre-screened, pumped through sand filters, disinfected with a chlorine system, and then temperature regulated before returning the water to the exhibit. Because these systems have been rehabilitated and reconfigured many times over the last 30 years, there are no accurate drawings of the existing conditions.
As part of the zoo's overall facility modernization, zoo operations staff, Quinn Evans Architects and PBS&J, an engineering firm specializing in a wide range of engineering services, initiated a data gathering effort to digitally define the habitat's existing environment in preparation for an extensive renovation.
As the mammals' antics entertained visitors in outdoor pools, the project team captured highly accurate as-built data of the habitat life support system. Surveyors did it with the help of High-Definition Surveying (HDS), an innovative high-speed data gathering technology. HDS, also known as 3D Laser Scanning, is a non-intrusive method of rapidly collecting highly detailed and accurate as-built data with centimeter accuracy.
Marc M. Muller, Resident Engineer with the Office of Facilities Engineering and Operations at the Smithsonian Institution-National Zoological Park, said, "The engineering team was able to get in and get out in less than three days without bothering the animals, the staff or our daily visitors. What's more, they were able to provide existing conditions along with recommended improvements in CAD-ready documents faster, cheaper and more accurately than conventional solutions."
Creating the Cloud
Each floor of the three levels in the life support system structure is jammed with electronic control systems, pumps, and equipment necessary to maintain this controlled environment 24/7/365. Mapping this data with conventional methods would have taken as much as five times longer and not been nearly as accurate because of the tight, complex equipment and piping environment inside the structure.
However, it's an ideal situation for the Leica HDS3000 3D laser scanner (Leica Geosystems). The system is easily maneuverable, requires only one- or two-man crews, and is able to fit into tight spaces.
Like any survey project, HDS requires some planning prior to application. Before initiating the scans, the HDS team walked through the three levels with the design team to visually locate critical tie-points and determine key instrument setup locations with the best visibility.
Surveyors established several positions on each floor of the equipment rooms to capture the existing conditions of the piping and equipment, and two setups outside to capture the water surface elevation of the two exhibits. Once in position, the surveyors simply set the scanner in the predetermined position, selected the desired measurement area and scanning density, and initiated the scan.
HDS technology incorporates an advanced 3D laser scanner that uses a laser to sweep across the subject surface to collect highly-visual and detailed point cloud data. A single instrument setup can literally capture millions of measurements, each accurate to a few millimeters. The scanner also contains a bore-sighted high-resolution digital camera that produces a true-color point cloud model of reality.
At each setup, the scanner remotely captured complete surface geometry of all exposed surfaces within the field of view, including the complex maze of pipes, electrical boxes, and irregular surfaces. The subsequent 3D point cloud automatically recorded onto a laptop computer wirelessly connected to the scanner.
In less than three days, the survey team captured more than 57 million three-dimensional points. PBS&J also utilized conventional surveying techniques to supplement the HDS. Members from PBS&J's Aquatics Design team worked alongside the survey crew creating sketches and recording measurements for piping and equipment in areas less accessible to the HDS equipment. Existing plan drawings were carefully labeled and digital photos were taken of the entire facility. This documentation also played a big part in verifying and defining existing conditions.
|Image-mapped (L) and Intensity-mapped (R) Point Cloud section view of the habitat life support equipment. High-resolution panoramic images are captured and draped over the data for realistic and easy viewing and data manipulation.|
From Cloud to CAD
Once the field work was complete, the HDS team registered the scans together to provide a complete point cloud of the entire life support system. The data was then referenced directly within AutoCAD using a plug-in called Leica Cloudworx for direct integration, which allowed for manipulation in a familiar CAD environment.
Within this program, surveyors quickly located existing piping and equipment centerlines using automated tools and generated accurate plan, elevation, isometric and 3D views of the life support systems. The zoo redesign team will use these highly accurate design documents as background files to design new improvements to the facility.
PBS&J surveyors found that the use of HDS on this project eliminated the need for costly field revisits and reduced the amount of time in the field to collect the data. In addition, the data accuracy was unbeatable. By collecting such accurate data (2mm precision when sampling points to create construction centerlines), surveyors reduced, if not eliminated the potential need of any field rework.
Although Gunnar, Selkie and Maureen will never realize the extensive modernization plans of their longtime home, the zoo staff and visitors can be assured that these fun-loving creatures live in a safe and comfortable environment.
Muller concluded, "The National Zoo is over 100 years old and modernization is complex and costly. It's critical that we find and use technology such as HDS to help us provide the best environment for our animals and a quality experience for our millions of visitors."
Travis Reinke has been using laser scanning technology for five years and has successfully completed numerous as-builts of plants and refineries, roadways and airport runways, and bridges and overpasses; he can be reached at (281) 529-4287 or firstname.lastname@example.org. John Kammeyer has been designing life support systems for aquatic animal exhibits for more than 17 years; he can be reached at (760) 753-1120 or email@example.com.