The most critical element in both architectural and engineering design is accuracy. Renovation and restoration projects often present the greatest challenge to accuracy, because precise placement of existing structures and components requires the highest level of attention to detail. Obtaining critical information becomes a time-consuming and costly endeavor, but there is a better way. Using laser scanning and Revit building information modeling (BIM) software, architects and engineers can achieve exacting accuracy, time savings, and cost-effectiveness.
Failure to provide design accuracy in any type of architectural, engineering and construction (AEC) project can produce devastating and costly consequences. Precision measurements and accurate representation of all the instances found in an existing structure are the most secure means of avoiding these consequences. Obtaining this information presents challenges, including:
- Exact exterior dimensions. Depending upon the structure taking exact measurements of a structure’s exterior can be next to impossible without specialized equipment.
- Exact interior dimensions. This often requires a preliminary sketch of interior conditions along with repeated measurements.
- Placement of equipment and components. Achieving accurate placement typically includes specialized equipment as well as access into the areas where they are located.
- Accuracy. It is time-consuming and often physically challenging to measure an existing structure, which often contributes to a breakdown in accuracy and the necessity for multiple trips to the job site.
- Time consuming. Obtaining dimensions and equipment placement typically includes preliminary sketches, drawings, photographs, measurements, and multiple trips to the site to confirm information.
Expensive. Adding up the costs of specialized equipment, multiple trips to the job site, the time to create preliminary drawings, and labor costs, gathering accurate information of existing structures becomes one of the most expensive parts of a renovation project.
Taking a series of photographs, which could be scanned and added into computer aided design (CAD) software, seems like the ideal solution to these challenges. That technology already exists, and on a scale that provides a trustworthy level of accuracy using laser precision.
Components of Scanning
The idea of being able to scan photographs of existing structures and convert them into CAD drawings has been around almost as long as CAD software and scanners. The technology to produce the precise results demanded by this approach has undergone significant improvements and innovations to arrive at its current level. To understand these advancements requires an examination of the different components of scanning, which include building information modeling (BIM), Revit software, and laser scanners.
AEC professionals utilize the information and tools of the intelligent 3D model-based information provided by BIM to optimize design, construction, and maintenance of both buildings and infrastructure. In essence, BIM has taken CAD to a level that reaches well beyond the realm of the bidding and construction plan-sets of the past and taken advantage of automated intelligence in the form of 3D and parametric object-based design to achieve a higher degree of accuracy and versatility.
Among the most innovative forms of BIM software, Revit provides full, bi-directional associativity to a CAD model. This means that a change at any point in a 3D model automatically updates throughout the model without additional user interaction. This is possible because BIM is not a series of lines, but representations of real world 3D objects. Revit not only provides seamless updating, but it keeps a relational database of the entire history of the model. Recent innovations to Revit have provided the conduit through which scanned real world images integrate into CAD with seamless accuracy.
The age-old computer science acronym GIGO (garbage in, garbage out) applies to BIM. The accuracy of the information delivered to Revit is a critical element in the overall accuracy of BIM. A greater level of accuracy is possible through laser scanners, which have enjoyed enormous technological innovations in the second half of the current decade. Laser scanners are able to record the shapes and the appearance of structures and objects in the field, converting them into a cloud of data points. Creating and updating 3D models is possible using this cloud of data points to construct the various existing objects and elements with real world dimensional accuracy.
Cost Barriers to Scanning
The main inhibiting factor to the use of laser scanners by a broader range of AEC professionals does not relate to accuracy or the availability of BIM systems, but to the cost of laser scanners. Up until recently, the purchase of a 3D laser scanner with the required level of precision has required a six-figure investment.
Greater competition in the market has reduced that investment to just over $50k, which includes the scanner, software and user orientation. Though $50k is a significant investment, when compared to labor costs and specialized equipment, the savings provided by a highly accurate laser scanner pays for itself after 3 to 5 projects. What has traditionally required numerous hours can take less than an hour to scan and an additional hour of postprocessing and uploading. In essence, laser scanning combined with Revit BIM technology provides a cost effective solution, which offsets the initial investment.
An additional challenge for some firms is the availability of adequate systems to support Revit and other BIM software as well as adequate storage to support the data cloud produced by a 3D laser scan of a job site. System considerations for handling this technology include:
- 3 to 10 TB storage capacity
- Solid State HD
- 64 GB RAM
- High-end graphics cards
- Network capacity to handle high volume traffic
Though these are advanced systems requirements, they are not outside what is becoming the norm for most AEC professionals.
The cost of laser scanning equipment, BIM software, user orientation, and the systems required to operate them represents a significant investment for most firms. However, an investment into the technology of laser scanning to Revit BIM is an investment into a vehicle for cost effective growth. As laser scanning and BIM innovations continue to provide more intelligent, cost-efficient solutions to the traditional challenges included in design accuracy, the investment question changes as well. One should consider an investment into these technologies, not based on whether a firm can afford them, but whether a firm can afford not to have them.