By John Smits, VP of Architecture & 3D Scanning ~ East Coast Metrology.
Our appreciation of modern technological advances quickly fades. No matter how cutting edge the development may be, we’ve grown accustomed to expect more and more with every passing year. Less than twenty years ago, in 2004, Leica introduced the HDS 3000, the first 3D large volume terrestrial laser scanner with a 360 degree horizontal field of view, and a typical scan time of thirty to forty minutes. Within five years Faro introduced the Photon 120, a thirty-two-pound behemoth that boasted the largest field of view; 360 horizontal x 320 vertical and scan times that broke the ten-minute mark.
Following those early scanners were a host of new and updated models, exhibiting substantial improvements in size, speed, accuracy, and cost. Soon mobile scanners entered the marketplace. Today there are an abundance of 3D laser scanners on the market, from traditional static scanners to hand held and wearable units. Many options are available in equipment and software. How does one discern what is best for their company or project?
Let us begin with a look at the industries’ need for large volume scanning. The most predominate use of 3D scanning’s point cloud image data is to provide as-built documentation, followed closely by construction verification. The deliverables most requested from that data are processed and aligned point clouds and 3D BIM models or 2D CAD drawings. These CAD models vary in scope, from a full-scale building model to a detailed analysis of a space or object’s surface deviations. The processed point cloud images and resulting 3D models can be used as a basis to create a digital twin or used within virtual reality (VR) devices, often using a hybrid of CAD models and scan imagery.
A good starting point to determine what type of equipment to use for laser scanning is the type of space or object to be scanned and the required quality of the deliverable. There are a multitude of options: Is the deliverable to be a CAD model or point cloud imagery? A portion of a building or processing plant or the entire facility? Interior or exterior? Will the CAD model be a basic floorplan for rough design or planning purposes or a precise model of all existing conditions, including MEP services? Another important factor to consider is the time available to scan the facility and the impact that time will have on the cost of services to the client. The answers to these questions will help in deciding what type of large volume scanning equipment should be considered.
Large volume scanners can be categorized within three generic types:
- Static Terrestrial scanners: Those that sit on a tripod and must be moved from position to position as the environment is scanned.
- Handheld scanners: As the name suggests, these are small devices that can be held in one’s hand, connected to a tablet device for monitoring the scan imagery as one moves about a space.
- Wearable scanners: Usually larger in scale then handheld devices, they capture data from multiple cameras and lidar sensors attached to a harness device worn by the operator while moving through a space.
Each of these scanners has features that are beneficial to meet specific objectives when preforming large volume scanning.
Static scanners can vary greatly in their level of precision and speed of use. Of the three generic types, static scanners typically have the longest range, up to 1000 feet. They also have adjustable degrees of resolution, which when coupled with their factory built precision levels, provide a dense, low noise point cloud dataset. While a drawback to these scanners is the slower process of data accumulation, which must rely on multiple setups within and around a space, the ability to position the scanner at various levels and locations within a space will provide data and imagery a mobile device cannot. For example, scanners can be placed high on a tripod to capture spaces above ceiling level, or set on a floor within a low pipe tunnel or crawl space. This can be beneficial for certain types of facilities or deliverables, overriding the issues of slower scanning time.
Handheld scanners are well suited to basic documentation needs, especially when used in large open spaces with minimal structural and piping detail required. They enable rapid movement through a space, quickly documenting spaces that could take days using a static scanner. The data quality may not have the clarity and accuracy level of a static scanner, but for many types of deliverables the accuracy levels are more than enough to meet project specifications. Handheld scanners are sometimes used in conjunction with a static scanner. The static scanner provides a precise dataset of the exterior envelope and portions of the interior levels. All remaining floor areas can be quickly scanned by the handheld unit. Both datasets are then combined within a CAD program to create an accurate comprehensive BIM model. The resulting time savings in total scanning time results in an improved ROI to the client.
Wearable scanners are one of the more recent entries into the large volume scanning market and are quickly gaining acceptance as a viable tool for the scanning industry. The increase in accuracy level, scanning distance, and image quality combined with their speed of data capture has made them particularly useful in documenting large expansive industrial spaces. Their ability to scan in a day what could take a static scanner a week’s time is a contributing factor to their market success. While there are limitations on its sensor’s placement locations, like the handheld unit it can be used in conjunction with a static scanner to provide additional data images and geo-reference controls for a final deliverable.
The choice of a scanner and software is important, but the skills of the device operator remain key to the success of any scanning project. ECM’s engineers have experience with the industry’s leading scanning equipment and software combined with a track record of hundreds of successful projects of varying size, type and deliverable. Our knowledgeable personnel will review your project parameters and recommend the equipment and methods best suited for an accurate, cost-effective deliverable meeting your company’s needs.
Contact ECM today and let our trusted expertise deliver the high-quality benefits of scanning technology to your next project.
