BIM (Building Information Modeling)

Scanning Firm Fast-Tracks Hospital 3D BIM Creation

September 16, 2013
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Elkhart General Hospital in northern Indiana completed construction of a new wing less than 10 years ago, but already another addition is in the works. Opened in 2005, the three-story west wing of the 100-year-old structure gave the hospital a much-needed centralization of its oncology services and an expansion of its birthing center. But more space is needed, and plans call for adding another five stories on top of the new wing.

Hospital expansions seem to be occurring everywhere, according to David Furlong, facilities management director of Elkhart General. “There’s always a need to keep up with medical advancements, and many hospitals simply don’t have the existing space to handle new technologies,” Furlong says.

The construction boom is a boon to companies such as PrecisionPoint Inc., a 3D laser scanning and BIM modeling solutions firm in Carmel, Ind. According to company president Mark Hanna, a 3D BIM with MEP included is critical in designing an addition for a hospital or other commercial building because the architects and engineers have to know where the existing pipes and conduits are so new ones can be designed and installed in the void spaces without conflict.

“Laser scanning is the most efficient way to capture the architectural and MEP as-built information needed to create the 3D BIM,” Hanna says.

Although the firm scans a variety of structures, including historic buildings and manufacturing plants in support of architectural design, hospitals have been among its most frequent and most difficult assignments. The challenge in hospitals stems from the fact that MEP is hard to access with a laser scanner because almost all conduits and piping are kept away from patients above the drop ceiling to minimize exposure to infectious contaminants.

“There are two time-consuming pain points in modeling MEP,” Hanna says. “The first is getting access to scan the assets behind the ceiling tiles, and the second is extracting the MEP geometries from the scans.”

Ideally, the crew simply would remove all the tiles before scanning a room, but a hospital never sleeps and there isn’t time to take a patient room out of service for a long period. At Elkhart General, however, Hanna neutralized the ceiling tile problem by developing a homegrown solution using a FARO Focus3D high-definition scanner, a rolling tripod and a Kindle Fire tablet.

Also, the PrecisionPoint team significantly reduced the time needed to extract the MEP geometries from the scan point clouds and model the pipes. Rather than perform the extraction and modeling work in Autodesk Revit by inserting the point cloud into that software and modeling the pipes using its native tools as they have previously, the PrecisionPoint technicians used the ClearEdge3D EdgeWise MEP for Revit software as the in-between solution that enabled the pipe geometry to be automatically modeled and then inserted into Revit as pipe families, shortening the 3D BIM project from eight months to just eight weeks.

 

The AEC firm contracted to design the new wing was provided with 2D drawings of the original construction plans representing walls, ceilings, floors, windows, doors and other architectural elements. These were converted into a 3D architectural model in Revit, but the architects were not confident the new model accurately represented the as-built hospital addition. Likewise, structural engineers created a structural model of the support beams that formed the skeleton of the building − also based on drawings.

The hospital owner’s representative firm, Chicago-based Navigant Consulting Inc., which worked with PrecisionPoint on previous hospital projects, hired the Indiana firm to scan the wing as well as the existing mechanical rooms to validate the architectural model and to generate a 3D MEP so the two could be merged with the structural model to create a comprehensive 3D BIM upon which the expansion would be designed.

Prior to scanning the 200,000-square-foot interior of the existing hospital wing, PrecisionPoint’s 3D Scanning Project Manager, Jay Scanlon, PLS, established a survey control network that would become the starting point for the scanning and ensure that all of the areas captured by the scanner were accurately geo-referenced to the existing architectural model.

Surveying with a total station, a traverse was made around the outside of the existing wing to locate the exterior of the building. This survey was then extended into every floor of the wing through doorways and up and down stairwells to tie together all of the floors from the basement to the roof. This was accomplished using the reflectorless feature of the total station to locate checkerboard targets attached to the walls inside.

“When tackling a project of this size and complexity where the number of scan positions reach into the thousands, a well-established survey control network is vital for accurately and efficiently registering the scans together,” Scanlon says.

The targets were left in place as tie points when the crews began scanning the interior hallways and rooms. Interior scanning was conducted with two Focus3D high-speed terrestrial laser scanners from FARO Technologies Inc. of St. Mary, Fla. The crews set up each interior scan to pick up a minimum of five scan targets, which also would be used during processing to merge or “register” the scans.

Having scanned hospitals before, PrecisionPoint knew its access to patient rooms would be limited because they have such high occupancy rates. These rooms were where the scanning crews needed the most time. Working closely with hospital administration on scheduling, Hanna’s team introduced a new scanning procedure using two Focus3D units.

PrecisionPoint attached a mount for the scanner to the top of an elevating tripod. With castors on its feet, the tripod could be rolled quickly into place and raised up to 16 feet in the air. A second mount was attached lower on the tripod frame to hold an Amazon Kindle Fire tablet.

“The scanner has a wireless interface that can be displayed on the Kindle Fire screen so we could operate the scanner remotely [from below] once it was out of reach,” Hanna says.

The two-person PrecisionPoint crew was alerted when a patient was discharged from their room. The first technician went in and set up a scanner on a stationary tripod. He quickly placed spherical targets on the walls about two-thirds the distance up from the floor to ceiling. In normal operating mode from two or three positions on the floor, the scanner captured architectural scans of the walls, floors and ceilings of the room, entry way and bathroom.

Next, the second technician rolled in the tripod-mounted scanner. His first job was to open a couple ceiling tiles and see where the scanner had to be placed to capture all the hidden MEP. For most rooms, three to five tiles were removed. The technician rolled the tripod under the exposed area and raised the scanner so that it just crossed the plane of the drop ceiling. The key was to make sure the scanner would capture a point cloud including MEP equipment above the tiles while also catching the spherical targets on the walls in the same point cloud.

“The targets served as the tie points between the architectural point cloud and the MEP point cloud,” Hanna says.

The technician below then activated the scanner via the Kindle interface. As the point cloud was collected, it could be viewed on the tablet screen. This let the technician know that all the MEP was being captured. Collecting the architectural and MEP scans took about 15 minutes per room.

“The hospital cleaning crew came into the room to do their work after we left,” Hanna says.

The entire onsite surveying and scanning took two and a half weeks. Had the crews needed to remove patient rooms from service and open all ceiling tiles to complete scanning, this phase would have taken three times as long to complete, according to PrecisionPoint.

 

Back at the office, PrecisionPoint’s in-house team integrated the multiple MEP and architectural scans from the rooms and hallways using the FARO Scene software. Working in Revit, the in-house BIM 3D modelers took the existing 3D architectural model and compared it against the new point cloud scans, aligning and moving walls, floors and ceilings as needed. This updated and validated the 3D architectural model to ensure it reflected the as-built wing of the hospital.

“Then we moved on to extracting and modeling MEP features,” Hanna says.

For extraction of the pipes, conduits, round ducts and other features, they exported the point cloud to the EdgeWise MEP 4.0 for Revit software from ClearEdge3D of Herndon, Va. The scanning firm began using this package more than a year ago to automate what was once an entirely manual task of identifying MEP features in the point clouds and measuring their lengths, radii, elbow bends and diameters on the computer screen.

Manually, this process could take months in Revit, but the automated geometry extraction software cut that time by an average of 65 percent, according to PrecisionPoint.

The technician set up parameters in the EdgeWise MEP software to extract all pipes of 2 inches in diameter or greater from the point cloud. Analyzing the scans from one hospital room at a time, the software then identified pipes and accurately measured their actual dimensions, including the sags of long pipe runs or the radii of non-standard elbows. The software had the intuition to match pipe runs from one scan to another and one patient room to another, even if occluded from the scanner’s view by a wall or other obstacle. This data was recorded in an attribute table and later used to double check the accuracy of pipe sizes and locations.

“The automated extraction captured about 90 percent of MEP features in the scan cloud,” says Devon Kelley, a PrecisionPoint BIM specialist.

He cleaned up the EdgeWise pipe model data set using the pipe editing functions built into the software. This step involved manually extracting and connecting pipes by selecting or “windowing” that portion of the point cloud.  For areas that had portions of their runs hidden from view by equipment and other MEP features in the crowded spaces above the ceiling tiles, they used the “Easy Connect” feature to automatically complete these pipe runs.

Prior to the Elkhart Hospital project, PrecisionPoint would have then exported the extracted MEP data in the tables to AutoCAD as 3D centerlines and traced over in Revit as 3D pipe families. However, the newest version of EdgeWise MEP contains upgraded processing power and features so that it can be used for modeling as well as extraction, eliminating the translation through AutoCAD all together

“The problem was that Revit is a design package that expects everything to be planar and perfect at 90 degree angles so it brings challenges to existing-condition modeling,” Kelley says.

Overall, the modeling process in EdgeWise MEP is much faster and more accurate due to the shape recognition algorithm that detects pipes and elbows, Kelley says. By using the point cloud, the ClearEdge3D software accurately “best fits” the pipe to the points.

“The point cloud processing engine [in EdgeWise MEP] was optimized for faster modeling of denser scans in the new software,” Kelley says. “In the Elkhart MEP scans, we could visualize a much denser point cloud on screen at higher fidelity because of the increased processing power in the software.”

Not only did higher fidelity enable the technicians to identify visually smaller features, they were able to read identification tags on pipe in the scan and easily assign them to a family or system, such as steam, potable water and fire suppression.

For the Elkhart General Hospital project, PrecisionPoint completed about 75 percent of its pipe, duct and conduit modeling in EdgeWise MEP and then used Revit for the remaining 25 percent, mainly to draw in sprinkler heads and termination points for the pipes, Kelley said.

“We reduced the time require for MEP extraction by two thirds thanks to automation and then we trimmed modeling time by another 35 percent,” Hanna said. “Overall, we completed the MEP modeling–which was our primary deliverable--in six weeks when it would have probably taken 6 to 8 months without the automated software.”

 

Ultimately, the goal of using 3D scan-to-BIM services is to reduce the risk and cost of construction overruns that plague many building projects when using outdated as-built drawings that often do not reflect the actual building and systems existing conditions, Hanna said. With a field-accurate as-built BIM generated from 3D laser scanning, the Elkhart architecture and design team has the confidence of knowing they have reduced the number of potential change orders that can result from an inaccurate BIM. 

“Our clients are quickly discovering that the overall cost of our scanning and BIM services can be far less than the cost associated with a single major field change resulting from poor and inaccurate as-built data,” Hanna says.

 According to Elkhart General Hospital’s Dave Furlong, the 3D BIM generated in this phase of the project will provide cost savings for the facility far into the future–beyond the construction. Furlong plans to integrate the BIM into a new computerized maintenance system that will be installed at the hospital after the new wing is completed. 

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