History
The Mystic Oral School for the deaf is a historic school that has been unoccupied since 2016. Overlooking the Mystic River, the site houses a large series of buildings strung together which makes up the education building, a recreational building and a two-story house. The educational building is purposed to be developed into a new city center including a marketplace, restaurants and a brewery. The surrounding lot is to be built into over 700 housing units to accommodate the influx of workers from the naval base. The educational portion of the site is to be captured to create a historical snapshot of the current condition of the building as well as to produce plans for development.
Field Operations
A combination of target based and cloud to cloud registration techniques were used in order to capture the entire campus. Our surveyors tied into the coordinate system and elevation datum used by previous environmental studies. Additional points were required to be set throughout the building which included a minimum of three points per floor in each building wing. Control site lines were established through various openings to achieve solid control points throughout the interior and roofscape. Each point had a reflective target attached to it that the scanner could recognize. The process of setting control took six days in the field. In total there were 20 control points outside and 86 control points throughout the interior.
Once control was established the scanning process could begin. The laser scanning was carried out using a Riegl VZ400i. The building’s exterior was scanned from over 30 positions at the increased height of the Topolift, a truck-top mounting system for the Riegl VZ400i. Once the exterior ring of scans was captured, the interior scanning could take way.
Laser scanning of the interior was conducted by scanning each and every room, stairway corridor and attic. A scan would be taken at every threshold to create a link between exterior and interior walls. Once inside the scanner would be placed onto a dolly system to be easily rolled between each room. After one level is complete the scanner would be changed onto a lightweight, easily adjustable set of photography legs. This allowed for successful scans going up each set of stairs, the landing and then the top of the stairs. Working from west to east, the entire building was eventually covered. The ceiling tiles were removed in sections of the building to obtain data of the decking and structural members. Once the interior was complete each rooftop had to be scanned. A larger set of legs were used on the flat roofs to raise the scanner up to 14 feet above the roof elevation. This allowed for the scanner to obtain data on the sloped portions of the rooftops.
Summary
The scanning process took a total of 35 work days and over 2000 individual scans. Scan technicians took the data off the scanner and put it on the server every night to allow office personnel to begin aligning the individual scans. The scans were registered together, cleaned and exported to modeling software. The pointcloud was inspected for any alignment errors and compared with surveyed validation points. The software compares measurements taken from the pointcloud with checkpoints surveyed conventionally to check elevations and coordinates. A 3D model was created in Revit using the pointcloud as a basis for drafting. The model contains all of the architectural elements required for future renovations. Historical elements such as windows and doors were modeled at a high level of detail. The building information model will serve the development team as they work towards final concepts and throughout the construction process.
