This presentation is part of the 2017 3D Digital Documentation Summit.
LIDAR and Photogrammetry: Comprehensive Data Collection for Historical Preservation
New technology has altered the manner in which three dimensional data is collected and processed. From terrestrial laser scanners to unmanned aerial systems (UAS – , a.k.a. drones), three dimensional capabilities are expanding exponentially. The three dimensional point cloud data, whether collected by a laser scanner, or produced via matching common points in a collection of aerial/land-based photographs (photogrammetry), is revolutionizing the way that we view and utilize measurement information. Dense point clouds produce the appearance of solid walls, floors, ceilings, and roofs, allowing us to understand the context of existing conditions directly within design software, accelerating the workflow of producing high quality drawings and Building Information Models (BIM) for use in new construction and/or renovation.
This session will cover the different methodologies for collecting and working with data from both terrestrial laser scanning platforms, and high flying aerial photography captured by drones.
When using terrestrial laser scanning, the user places a laser scanner in a fixed position, typically on a tripod. The laser scanner rotates 360° horizontally, while an oscillating mirror reflects the projected laser beam vertically over a ranged distance. This fixed position and range typically results in a large number of positions being needed to collect measurements on all surfaces.
In contrast to laser scanning, small Unmanned Aerial Systems (UASs) provide a platform of data capture that can acquire information from a large variety of perspectives, in a short period of time. With a large variety of photos of the subject, complex photogrammetric algorithms can identify similar features, and place them appropriately in 3D space.
While both of these two data collection methods are extremely powerful on their own, the session will additionally discuss how these collection methods can be combined to allow for more comprehensive coverage in building/site/object documentation.
Before taking to the skies, it is imperative that technicians understand the rules and regulations which govern the National Airspace System (NAS) relating to the use of Unmanned Aerial Systems (UASs). The session we will briefly summarize these critical regulations, and include some tips to help others plan successful UAS flight missions. The session will also touch on the ability to work with point cloud and 3D surface data in major software packages, including Revit, AutoCAD, and Navisworks. With access to rich data such as these, design, restoration, and preservation efforts are hastened tremendously.
Brief case studies will include our recent collaborations with the National Park Service (NPS) in documenting the Lincoln Memorial and Washington Monument on the National Mall, as well as project examples which combine laser scanning with photogrammetry.
Jon W. Adams oversees the development, monitoring, and implementation of procedures for high-quality BIM documentation and data processing. Jon has been with DJS Associates, Inc., since 2008 and is involved with the planning, overseeing and execution of site documentation, as well as the creation of 2D and 3D as-built models. Through this hands-on approach, and attention to detail, he is able to help clients determine how to best address their needs on a case-by-case basis. He has been the coordinator and team leader of many complicated preservation projects including the documentation of the Lincoln Memorial and the Washington Monument.