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Data Collection in AEC (AEC Insight Column)
1 Jun, 2008 By: Jerry LaiserinLinking the real world to the virtual world.
Steady increases in the power, performance, and sophistication of computer hardware and software enable AEC project teams to maintain their design, documentation, and delivery processes entirely in the digital realm. For new buildings, freestanding on virgin sites, such digital or virtual project processes might provide all the information needed for real-world construction. However, any project that involves repairs, alterations, or additions to existing buildings or that requires infill between or among existing buildings also requires capturing information about those buildings and bringing that captured data into the digital realm. Thus, AEC data collection closes a loop in the project process of the following:
- 1. capture of data about existing or as-found physical conditions
- 2. transformation of captured data to digital models
- 3. digital modeling of new work integrated with a digital model of existing conditions
- 4. construction of new work within the existing work, based on the integrated digital model
- 5. capture of data about as-built physical conditions
 In this article |
Although several techniques are available for digital data collection, all have significant advantages over manual measuring methods in terms of higher speed, greater accuracy, and lower cost.
Line of Sight
The two most popular techniques for AEC data collection for existing buildings are photogrammetry and laser scanning. According to Wikipedia, photogrammetry is a process whereby "three-dimensional coordinates of points on an object are determined by measurements made in two or more photographic images taken from different positions. Common points are identified on each image. A line of sight (or ray) can be constructed from the camera location to the point on the object. It is the intersection of these rays (triangulation) that determines the three-dimensional location of the point."
Although photogrammetry dates back to the nineteenth-century origins of film photography, modern digital cameras and software such as Eos Systems' PhotoModeler vastly simplify and accelerate the process of photographing, measuring, and modeling 3D points on or in an existing building.
Designers who frequently need to capture existing conditions data and measurements might opt to purchase photogrammetry equipment and software. Occasional users could find that it's more efficient and cost effective to call on experts who provide photogrammetry-based building models as a service, especially on projects that entail highly specialized historic preservation work. Frazier Associates of Staunton, Virginia, is an architectural firm that has developed in-house expertise in photo documentation of historic structures, which the firm provides on its own projects as well as a service to clients across the United States. Frazier Associates also provides rectified photogrammetry, a further specialization that delivers scalable images.
Measure for Measure
Many architectural projects, such as tenant fit-out of office or retail space, require only floor plans of as-built conditions. Companies such as GiveMePower focus exclusively on these needs, which some observers have labeled BSIM (building surveying information management). Demand for BSIM is growing so rapidly (65% per year) that GiveMePower recently switched its business model from selling tablet-PC–enabled CAD and measurement software (PowerCAD Site Master) to being a pure building surveying services provider, nationwide. Other national providers in this market include Existing Conditions and Asbuilt Services, both of which go beyond floor plans to deliver full architectural drawings of both interior and exterior construction.
However, facility and project owners' survey requirements often encompass much more than documenting spaces through plans and elevations. This is especially true for large, multiple-location financial, retail, service, and hospitality businesses that could have hundreds — even thousands — of bank branches, stores, showrooms, gas stations, hotels, restaurants, or the like. In this context, the terms site survey or facility survey expand to include tasks such as brand compliance, condition assessments, signage audits, illumination audits, and so on. Imagine the task of bringing several thousand branch-office locations up to a uniform corporate appearance when two large banks merge or one wireless telephone provider acquires another. Coast 2 Coast Surveys targets this large market segment with a comprehensive lineup of services for even the largest nationwide rollout projects.
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About the Author: Jerry Laiserin
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