Virtual Design Analysis Group is a division of NVentum, LLC.

This unique collaborative endeavor; to utilize the latest reality capture technology to document the artifacts, buildings and campus of History San Jose, provides opportunities for private sector, non-profits and institutions of higher education to work together to solve some of today's most pressing engineering issues. The protocol for retrofitting as-built historic facilities and the use of new technologies to preserve our most prized historic treasures are vital to the continued success and expanded influence of our museums.
This blog will document the challenges and successes of this ambitious, one of a kind project.

Tuesday, August 23, 2011

A Brief History Of Laser Scanning In The U.S.

 Laser scanning systems first became available in the US in the mid 1990s and were first put to use by oil refinery and chemical plant operators who had seen their plants expand and change over time but without accurate as-built drawings being kept. The cost of shut down while repairs or renovations are carried out can be enormous and therefore owners want to limit downtime to the absolute minimum. The use of a laser scanner to create an accurate as-built record of an area perhaps hazardous for humans to access became an essential tool for plant operators.

Builder Total Station
The arrival of laser scanners for building surveys introduces a new era – not just for surveyors and general contractors but also for building owners and managers who need accurate plans and drawings quickly, without the inconvenience of providing special access equipment. Laser scanning also offers the potential to move into 3D modeling with the confidence that the data captured is an accurate representation of every detail of a building or structure, however complex or intricate the detailing. There is little doubt that this exciting new technology will be used increasingly as an alternative to existing methods.

Imagine setting up a small machine on a tripod in the middle of a room. You switch it on. For the next few minutes it scans and rotates. At the end of a few minutes activity it has captured enough data to produce accurately dimensioned drawings of all the room’s features – window reveals, mullions, transoms and soffits, intricate cornices, crown moldings or even the complex moldings of Grecian columns. This is the advantage of today’s laser scanning technology.

The data the laser scanner has captured during its brief period of activity allows the operator/user to generate sections and plans. The data is converted into a three-dimensional model for use within a CAD system or perhaps for incorporating in a virtual reality scene or Building Information Management (BIM) or other computer modeling system. The potential is vast and the results are very impressive.

The effective use of a laser scanner requires a person with multiple skills. One needs the knowledge of a construction foreman to evaluate its suitability for a particular project, also to understand what data is necessary to complete the given task. The operator needs the vision of a photographer to visualize the end product and develop the scanning sequence. Lastly, the operator should have an understanding of surveying techniques to help develop layout and workflow. These machines capture vast amounts of data very quickly, and it takes a surveyor with knowledge of building construction as well as reality capture technology to know what can be discarded and what data is necessary for the final drawing or digital CAD model.

So, what can we expect from this new technology? For a person with the described skill set, what type of careers paths might open up in the foreseeable future? Currently, reality capture/laser scanning technology is being used in civil engineering; from seismic retrofitting to virtual design. Reality capture is being utilized for documentation of forensic accident/crime scenes. Archaeologist use laser scanning to document excavations and reconstruct ancient ruins. The GSA uses laser scanning to document government facilities for condition monitoring and asset management. From the private sector to non-profits, local and federal government, the use of laser scanning technology is expanding as new applications continue to be developed.

The expanded use of laser scanning will ultimately spawn a host of new career opportunities. Laser scanning is the first step in a process. Once the scan is completed, there is the task of processing the data; the point cloud. Processing point cloud data requires computer skills, along with the ability to interpret blueprints or schematics and a sound understanding of the field of application. For example, if using this technology to excavate a site, a strong background in archaeology is a prerequisite to success. If applying this technology to crime scene investigation, an understanding of forensic investigation is an essential component to the desired outcome. The laser is a tremendous tool in the hands of a trained professional.

Once the scans have been completed, you have a point cloud and the 3D model completed, what next? The 3D model is a data base that must be updated and maintained. Building owners and operators will need to hire a BIM systems manager or operator to insure the facility and investments are protected and operating at peak performance. What about facilities that don't want the expense of  hiring full-time person to manage their BIM systems?  Opportunities will arise for companies to market themselves as maintenance companies that manage and update BIM systems for facilities. I see new companies whose sole business is the maintenance and operation of BIM systems. I can also see some of today's corporate giants entering the field of BIM operations. Can you image H.P. or Google starting a BIM operations division? Not out of the question....

So how can a laser scanner help in building conservation? Building renovation and conservation projects invariably need accurate plans and drawings of the existing layouts and features before the specialists can begin their work. But historic buildings are notoriously poorly documented and accurately dimensioned drawings either don’t exist or have been lost with the passage of time. Even structures built in the 1960s and 70s often lack any detailed record of how they were built and in some cases are beginning to pose a hazard for those who have to alter or demolish them.
Leica Geosystems HDS6200

NVentum’s laser of choice is the Leica Geosystems HDS6200. The laser scans an area of 360 degrees by 270 degrees. It also has the advantage of being able to capture all of its data from ground level; no scaffolding, hoist or crane is necessary as the scanner can do its work at ranges of up to 79 meters from the surfaces being measured. The accurate measurement of the scanner’s laser pulse (which is emitted at a rate of up to 1,000 per second) is critical and can be a major source of errors in the hands of an inexperienced operator. Experienced surveyors can then carefully analyze and process the point cloud data so that the most accurate measurements possible are captured for drawings, as well as ensuring that digital files are not overloaded with surplus data. The density of the point cloud captured will depend on the range of the scanner from the surfaces being measured: the closer the range the denser the point cloud.

...more to come...

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