Wyoming Middle School is situated on 6 acres in a residential neighborhood in the City of Wyoming, Ohio, a small suburb near Cincinnati where more than 8,000 residents enjoy an abundance of historic buildings and charming streetscapes. Built in 1927, the three-story, 102,000-square-foot middle school is on the National Register of Historic Buildings.
In 2011, the Wyoming Board of Education outlined a plan for renovating the historic building to improve the learning environment and increase safety. Necessary updates included an upgraded electrical system, an enhanced security system and automated fire suppression. Improved access to the building was also a primary concern. In March 2012, the Wyoming community voted to approve a $25 million bond that put the plan into action.
The school board selected a design and construction team composed of Kleingers & Associates Surveying and Civil Engineering, Ruetschle Architects, and Turner Construction. The project goals involved demolishing three old building additions and creating two new additions that would tie into the original structure; providing safer pedestrian access; installing new windows throughout the building; and conducting a traffic impact study for improved onsite automobile traffic routing.
Little to no documentation existed on the original building or the additions added over the years. Kleingers & Associates, which was originally included on the team to provide the topographic survey, site engineering, landscaping architecture and the traffic impact study, saw an opportunity to further aid the efforts of the team through 3D laser scanning. “Including 3D laser scanning operations would help the architects by providing a complete record of the existing façade on the south side of the building where the new additions are scheduled,” said Brian Elbe, HDS manager for Truescan3D, Kleingers’ 3D laser scanning focused service division. “It would also reveal subtle nuances that would otherwise be very difficult to detect through conventional methods, such as varying building corner angles and irregularities in the vertical surfaces of the building.”
Turner Construction, which uses virtual construction and BIM coordination for streamlining field operations, immediately saw the value in having the exterior of the building scanned. The amount of data collected through scanning could dramatically reduce the number of change orders that are typically associated with a project of this scope, thus keeping the project on budget and on schedule for the school district. Having the opportunity to document the locations and precise dimensions of all the windows for contractors was also an obvious benefit.
By providing 3D modeling or “scan to BIM” services, the Truescan3D team could deliver a highly accurate Revit model of the exterior of the building, easing the design burden shouldered by the architects. Ruetschle Architects saw the opportunity to have a 3D representation of the building to design against as a tremendous advantage and an opportunity to avoid having to field verify measurements and rework.
“When providing a Revit model of the building, we are essentially eliminating the need for the architect to hand measure and then later transcribe their field measurement notes back into the computer,” Elbe says. “They can design directly to our data, which is far more accurate, detailed and provided to them in a fraction of the time that traditional methods would take.”
The team was in agreement, and Truescan3D was commissioned with scanning the entire exterior of the school.
A coordinate system had already been established by the Kleingers & Associates field crews as part of the conventional surveying operations on the site. The Truescan3D team was able to use the existing control network to associate the scan to the same coordinate system by setting new scan position control points, tying them into the control network conventionally, and then executing scans from these new positions.
After the control was established, one of the challenges faced by the Truescan3D team in collecting the field data was efficiently capturing the data from limited positions due to the number of trees growing near the building.
“The trees, which really add to the charm of the overall site, made it difficult to find setup positions that would allow us to scan the vertical limits of the building face,” says Tim Stamper, 3D laser scanning technician. “We had to scan close to the building to make sure we were getting coverage on as much as possible, but doing so gave us a less than desirable angle of incidence. To compensate for that and to make sure we were covering everything needed by the client, we then set up closer to the street to fill in areas higher on the building face.” Although the additional setups added to the time in the field, the extra effort paid off by providing more detail in the final point cloud.
The south faces of the building were end-capped by the old building additions that were scheduled to be demolished. Accessing the upper floors and getting accurate measurements for the additions proved challenging; the Truescan3D team needed to be able to see the faces that were to remain while being able to observe common points in the scans performed from the ground.
To do this, the team performed several scans from the rooftops of the building sections slated for demolition. These scan positions were set strategically so that the scan targets used to register or combine separate scan setups could be observed from the ground and across the span between the buildings while allowing the team to observe the subject building face in its entirety.
In addition to documenting the façade of the building and the window locations, the point cloud also provided unforeseen value to the survey team. The scan was used to verify line work collected by the conventional survey crew in areas that were difficult to visualize from the conventional data alone. “Having the point cloud as a reference saved us from needing to revisit the school to answer questions about the site,” explains Matt Habedank, project surveyor at Kleingers & Associates. “With our survey schedule being full, it’s nice not to have to pull a field crew from one job to verify something on another job; the point cloud did that for us. In a roundabout way, our clients not using laser scanning on their jobs still indirectly benefit from us using it on this site; no one likes their project schedules getting delayed.”
Once the data collection in the field was completed, the Truescan3D team brought the data into the office to begin working on the deliverables--a Revit model combined with a Civil 3D topographic surface of the site.
Using Autodesk Revit 2013 and its PCG database engine, which drives the point cloud functions, Truescan3D was able to import the point cloud and create a parametric model of the existing building in 3D. Modeling with the point cloud proved much more efficient than using hand measurements. “Having come from the practice of interpreting everything from hand notes into Revit, I really appreciate the huge time savings and ease of use resulting from referencing the 3D point cloud data directly in Revit and modeling from it,” says Teresa Erwin-Mullins, 3D modeling technician. “I can carve it up and spin it around any way I want to look at it, and I know that I am always looking at exactly what it is in the field; there is little opportunity for error. And as a bonus, it’s kind of fun!”
Once the Civil 3D surface model and the building model were completed, the surface model was referenced into Revit and used to create a Revit Toposurface, or site surface, that was stylized and used as a reference to create other 3D objects like sidewalks and drive aisles. For a more realistic 3D representation of the site, the Civil 3D 2D line work was referenced for placing trees and other landscape objects identified during the topographic survey.
One challenge in merging these datasets was understanding how each type of software handles coordinates as they relate to the respective discipline using them. For example, surveyors might use a Civil 3D drawing with an origin point set to 0 and either work on assumed coordinates, such as 5000, 5000, 100 or on published coordinates such as a state plane system, with drawing files in distance units of U.S. survey feet. In Revit, many projects are set up so that the project origin point is close to the subject building with drawing distance units of inches. Ensuring that the two datasets would cooperate when data was being passed between them required some forethought during setup. However, once the settings were worked out, the data exchange worked well and resulted in a streamlined process.
Models for both the building and the site surface have been completed, merged and delivered to the design team. “One of the great things about working with this technology is that it always returns benefits beyond how it was initially intended to be used,” Elbe says. “Whether it is verifying elevations, revealing deviations in construction from record plans or just locating power outlets or sprinkler heads, it always over-delivers on what it was originally intended to do.”
Although construction on the Wyoming Middle School renovation project has yet to begin, the scans are already delivering benefits. “The deployment of laser scanning of the existing skin of Wyoming Middle School, a building close to 100 years old with several renovations under its belt, has been integral to our planning process,” says Mike Dooley, virtual design and construction engineer at Turner. “We can now identify undocumented changes to the building and understand how it affects our preconstruction budget and project schedule.
“Prior to laser scanning, it was common to run into undocumented field issues with the skin, which affected schedule and budget,” he adds. “Now we have technology and processes in place to work around that.”
Read the related article, "Six Ways to Boost Your Scanning Services," on GeoDataPoint.com.