By Steve Rizer
A new augmented reality modeling system allows a contractor to determine whether a project is on, ahead, or behind schedule, leading to cost savings and a reduction in project delivery time, according to Virginia Polytechnic Institute and State University. Mani Golparvar-Fard, an assistant professor of civil and environmental engineering at Virginia Tech, developed the system, called 4 Dimensional Augmented Reality (D4AR), which the institution believes provides new possibilities for the construction industry, including evidence for dispute resolution, safety inspection measures, progress evaluation and analysis, and faster, more accurate as-built versus as-planned evaluation.
The system automatically analyzes physical progress on large-scale construction projects, the university stated. “Without the need for a Global Positioning System (GPS) or any other location tracking technology, the modeling system ... is able to geo-spatially store digital pictures of a building in 4D (3D plus time) and integrates the photos with building information models (BIM) during any and all phases of construction.”
With the widespread popularity of digital photography, on-site pictorial recordings of construction projects have become a daily part of the building process, according to Virginia Tech. Golparvar-Fard added: “Field engineers might take about 250 pictures per day, providing a wealth of visual information. However, the challenge remained about how to automatically determine the three-dimensional geometry of the construction site from the unordered and uncalibrated collection of images. Furthermore, the images needed to be accurately registered with BIM in a common three-dimensional environment, allowing performance of the project in forms of physical progress, cost, and delivery time to be systematically analyzed.”
Golparvar-Fard achieved this caching in his method by reconstructing as-built 4D point cloud models from the unordered daily site photographs and comparing the reconstructed models with BIM using a new computer vision and machine learning-based method.
“The augmented reality system also gives the construction industry the ability to automate and remotely monitor the safety, quality, and site layout,” Virginia Tech stated.
“His modeling environment allows the “integrated visualization of as-built and as-planned models,” Golparvar-Fard explained. “With the D4AR models, any user is able to load their digital photo logs for a specific building, reconstruct a 3D scene, and navigate through the pictures by location and time. The D4AR models also provide users with the unique ability to organize and integrate their daily construction images with BIM and project schedule, and interactively browse through the geospatial configuration, saving time and delivery time.”
Golparvar-Fard is commercializing the D4AR tool through a spinoff company he started with Peña-Mora and Silvio Savarese of the University of Michigan -- Ann Arbor. The D4AR modeling system is undergoing testing by Turner Construction with the World Trade Center and several other construction projects. Turner and the National Science Foundation helped fund the research.
Golparvar-Fard also is expanding this modeling method to other areas of research from rapid energy performance modeling of existing buildings to structural stability analysis.
Golparvar-Fard began his work on the D4AR modeling as a graduate student in 2007 at the University of Illinois at Urbana-Champaign when he superimposed a three-dimensional building information model over time-lapsed images and used a metaphor based on traffic light colors to represent performance deviations.