Tips on Purchasing a Laser Scanner

Written by Michale Olsen
Saturday, 26 May 2012

The selection of a laser scanner can be a difficult decision.  Let’s face it, they all are cool and it would be nice to have one of each!  But ultimately, it is a significant investment and you want to make sure that you get the optimal value out of your purchase.  Laser scanners may have specific purposes, environments, or applications for which they are best suited.  Caution must be used when comparing scanner specifications because there are no consistent standards for testing and reporting, although the ASTM E57 committee is working to address this issue.  For example, the accuracies of scanners vary non-linearly with distance and some manufacturers publish accuracies at 50 m and others at 100 m.  Overall accuracies are influenced by the surface being scanned, geometric configuration of the scanner and target, environmental conditions, laser properties, and many other factors.  Point of Beginning offers a very helpful list of specifications (usually updated yearly) for a variety of scanners and should be consulted by anyone looking to purchase a scanner.

As I have discussed in previous articles, scan geo-referencing can also induce error.  For example, the accuracy of a survey grade GPS unit is typically 1.0 cm in the horizontal and 2.0 cm in the vertical.  Thus, data acquired from a scanner with a millimeter level accuracy will no longer be of millimeter accuracy if GPS is used for the scan geo-referencing.

Some criteria that should be weighted in the selection of a scanner include (although not limited to):

1. Type of laser (wavelength) – How well does the laser reflect off the type of surfaces to be scanned?  Are you scanning metal objects, topography, wet surfaces, dark surfaces?

2. Spot size (pulse width, beam divergence) – What will be the size of the laser spot on the target?  Do features smaller than this need to be modeled?

3. Speed – The most common question/metric is: How many points does it collect per second?  Most scanners are fast so this is not the most crucial ifnormation.  A more important question is: How much setup time (e.g. mount the instrument, boot up, select scan window, acquire imagery\targets, and scan) is involved?  The latter can dominate a lot of the actual field time required.  Another question is how much processing is required and what workflow optimizations are presented by the scan manufacturer.

4. Field of View – How wide is the scan view? (Many scanners can scan 360 degrees horizontal, but have a limited vertical window).

5. Accuracy – What level of instrument measurement error is acceptable to fit into your overall error budget?  This will depend on the intended applications.

6. Resolution – What point density is achievable/required?

7. Range – How much coverage is needed in a single scan?

8. Geo-referencing – Does the scanner have a calibrated GPS mount for geo-referencing? Or are external targets required?

9. Level compensators\Inclination sensors – Can the scanner correct for out of level setups, improving data quality?

10. Mobility, durability – Is the scanner designed for field operation?  Or is it meant to be an indoor scanner?

11. Photography – Do you need photographic information? Does the scanner use an internal or external camera?  What steps need to be taken to map the photograph to the point cloud if it is external?  Is the photograph taken simultaneously or as an additional data collection procedure?  How long does this take?

12. Software – What software package is used for aligning and meshing the scans? What features are available?  How does this package integrate with the other packages you are currently using?

13. Effects on humans – Is it eye safe? Will it set off security alarms (e.g., in cultural heritage applications, you may be scanning in a museum with an alarm system (I have had that happen before!))?

14. Maintenance – What are the costs associated with maintaining the scanner?  Many manufacturers offer maintenance packages.

15. Upgrades – Scanner technology evolves quickly.  Would you be able to upgrade your scanner (or obtain a trade-in credit) when it is time to upgrade?

Obviously you would also want to do a cost/benefit analysis when comparing different systems.  Ultimately, invite the manufacturers out and have them demo the scanner in the environment you will be using it in most frequently.  Also, ask them to let you demo the software so you can get a feel for the workflow and how that will integrate into your current operations.

If your agency is looking to purchase multiple scanners, a few questions arise.  Do you want to go with various types of scanners so that you have a versatile amount of equipment for any job?  Or is it better to standardize your equipment so that all personnel are using the same scanner, reducing training costs?

Good luck in your new scanner purchase!

originally published at LiDAR News http://www.lidarnews.com/content/view/9015/

It’s a bird…it’s a plane….

It is actually neither.  When you are using a laser scanner a short laser pulse is emitted away from the scanner and is reflected back by objects it hits.  A part of the reflected radiation comes back to the scanner where it is detected by a sensor.  Because the light-speed is known the time elapsed between emission and reception of the pulse can be measured and divided in half for the distance of the object.   The sun emits radiation on the same wavelength as the scanner, so when the receiving lens is pointing at the sun, it reads the sun’s radiation as well as the scanner’s reflected pulse. The second part of the measurement when discussing a Time of Flight scanner is time.  Since the scanner is timing the reflection relative to the emitted pulse, and the sun’s radiation “adds to” to the laser pulse and alters the timing and the result is an artificially high reading that seems to drift off into space.

Changes…

Technology moves so fast these days it is almost impossible to keep up with it all, but it is important that we do all we can to at least be aware of the changes.  You don’t necessarily need to rush out and buy the newest “thing” today, but you should know it is out there and how it will or can impact you, especially as a business owner.

In the CDS newsletter “Tools of the Trade” this month I did a technical segment on Building Information Modeling (B.I.M.) and the role of the Surveyor in B.I.M..  A year or even two years ago it was important to know what B.I.M. was about and that it was coming, today it is important to be looking at ways to take advantage of B.I.M. and position your company to be a B.I.M. Expert.

The role of the Surveyor seems to be changing in many ways today.  While some may look at the changes as negative, others see opportunities.  In the Construction world we have seen more and more companies move to 3D machine control and fewer and fewer stakes going in the ground.  Many would look at that and say the machines are taking the job of the Surveyor, but we should be looking at this as an opportunity.  As a Surveyor we should be building models, tying in control, providing checks, and performing other services that Surveyors are already able to do, but maybe not used to doing.  There is an article written by Houston Neal titled “Automation of Surveying Creates Disruption and Opportunities” that I think covers this topic very well.

Just getting back from the SPAR 2011 Conference I too am well aware of the changes that have happened in the last year as well as the changes coming.  Who would have thought that the scanner I use on my game console could be used to gather data for making working 3D models?!

B.I.M., HDS, Machine control, GPS, data collection, Field to Finish, or any other topic that affects, influences, or otherwise impacts your business is probably something we know about or deal with on a regular basis.  I want to be your partner in these changes and do everything I can to keep you as informed as possible and make sure we find ways to leverage your abilities and capabilities to keep you moving forward as things continue to change.

Automation of Surveying Creates Disruption and Opportunities

Surveying is going through a technological renaissance. The increased adoption of machine guidance systems has renewed the importance of the surveying trade. This technology calls for a highly-trained workforce, and surveyors are the most qualified for this job. But to get in on the action, surveyors need to learn to use this technology and re-brand themselves.

GPS Machine Control Has Replaced Traditional Staking
Unless you’ve been sleeping behind the wheel, you’ve likely heard of GPS machine control. Also referred to as machine guidance or automated machine control, these systems are widely used by heavy construction companies. They speed up work, improve grade accuracy and improve the billing and scheduling accuracy of jobs. For example, by calculating the amount of material moved in a day, they can substantiate bills or keep employees on schedule.

The premise behind the technology is simple: just like using GPS in your car, a GPS machine control system tells excavators where to drive equipment. Additionally, these systems indicate the grade to excavate at. Depending on which version is being used, machine control systems either provide instruction on where to position the blade or automatically do it for drivers.

GPS machine control systems replace surveyors’ old jobs – especially staking. Traditionally, machine operators relied on stakes for both position and grade information. With machine control, this information is relayed in real-time to a unit on the driver’s dashboard.

So if staking is no longer necessary, are surveyors still necessary? Absolutely. Historical roles like boundary resolution and topographic survey work cannot be automated, so surveyors will always be needed for these. But they are also the best people to take on more modern duties, such as managing the GPS machine control system.

A Picture of the Modern Surveyor
To stay relevant on the job site, surveyors need to take ownership of three roles: they need to calibrate the site, prepare data for the machine control system, and provide quality control and assurance of the finished grade.

Before any construction begins on a job site, surveyors are needed to set up the geodetic control. This is a reference system used to determine GPS coordinates. After the geodetic control points have been determined, the base station can be set and the site can be calibrated.

The next step is to create the 3D model that will be used in the machine control system. This is a huge opportunity for surveyors. Preparing data for the machine control system can be difficult and many contractors don’t want the extra liability. So they either outsource or hire exclusively for this task; some even dedicate entire teams to data preparation.

To own this process, surveyors must first learn to work with paper plans and CAD files. 3D data models are made with both types of plans. Often surveyors have to clean up drawings before building the 3D model. So it’s essential that they are familiar with the various file formats, to understand how to use them, and to be able to build the models afterwards. Finally, these files will need to be converted into a machine-ready format and uploaded into the machine control system.

“Someone has to have their fingers on manipulating the design into a format that goes into the computers on the machine guidance systems,” explains Tom Taylor, Chief of Surveys Coordination and New Technologies for Caltrans District 4 Surveys. “The best people to do this are surveyors. It’s a niche that surveyors are in the best position to provide this service for.”

Once the site has been calibrated and the data has been uploaded into the machine control system, construction can begin. But the surveyors role doesn’t end here. They will be needed during construction to monitor the machine control and to deliver quality control and assurance. No one is more qualified to provide quality assurance of grades than the surveyors.

Training and Branding: the Keys to Unlocking Job Opportunities
To take advantage of these job opportunities, surveyors need to learn to use this technology and “re-brand” themselves. As mentioned above, they will need to learn how to work with CAD files, how to develop 3D models for machine control and how to transfer data into the machine control systems.

“Maintain your expertise in the technology,” suggests John Watson, President of the Texas Society of Professional Surveyors. “Surveyors have always been at the forefront of technology and they need to stay that way. Always be learning. Always be training on new equipment.”

They should also become familiar with the major machine control packages on the market from companies such as Caterpillar, Leica, Topcon, Trimble and GeoPac, the software used by many branches of the Department of Transportation (DOT). Surveyors can get training directly from these companies, or one of the many partners that resell these systems.

In addition to getting training, surveyors need to brand themselves as machine control experts. Contractors, land engineers and surveyors are all vying for this title and no one has proved themselves in the role yet. Land surveyors are the most qualified for the job, so they should position themselves accordingly. And to support this claim, they need only point to the existing state laws that require surveyors to be part of the machine control setup process.

Salient Points

• Surveyors have an opportunity to work in more professional roles that require more thought than swinging a hammer or pounding a stake
• To win more jobs, surveyors need to take ownership of the following tasks:
  • Site calibration
  • Data preparation
  • Quality assurance and control

Leica Geosystems’ User Conferences

Leica Geosystems’ User Conferences for Laser Scanning and Airborne Sensing expand to become “Hexagon 2011” International Conference

(Heerbrugg/Switzerland, 11 February 2011) – Expansion highlights Leica Geosystems’ commitment to global customer base under the roof of its parent company, Hexagon AB.  Leica Geosystems’ High-Definition Surveying (HDS) Worldwide User Conference will participate in this new format, offering attendees an unprecedented variety of sessions, hands-on training, networking and new business opportunities. Also the Hexagon Airborne Sensor business is inviting the customers of Leica Geosystems and Z/I Imaging to join the “Hexagon 2011” Conference.

According to Juergen Dold, CEO of Leica Geosystems, “the HDS and Geospatial Solutions user conferences are well known amongst our customers. Now, also our partners in the surveying, mapping, and positioning technologies business can expect an exciting program under the Hexagon roof called “Trends in Mapping & Positioning for Government and Industry”.”

Hexagon AB, leading, global provider of 3D solutions to design, measure and position objects and to process and present data, will host its inaugural international conference, “Hexagon 2011”, 6-9 June at the Orlando World Center Marriott Resort in Orlando, Florida, USA. “Hexagon 2011” will bring together the latest technologies and user communities from Leica Geosystems, Z/I Imaging, Intergraph®, as well as Hexagon’s Metrology and Technology divisions, in one location to provide attendees with a user experience of unprecedented scope and value.

“Hexagon 2011” will feature more than 200 targeted break-out sessions and hands-on training courses tailored by tracks, previews of new technologies, interactive technical demonstrations and workshops and compelling customer testimonials. Additionally, the conference’s agenda includes insightful keynote presentations on industry and corporate trends as well as unlimited networking opportunities.

“The fusing of conferences into one unified “Hexagon 2011” conference underscores Hexagon’s steadfast dedication to its global customers and to delivering a conference of exceptional quality and value,” says Ola Rollén, President and CEO of Hexagon AB. “Every effort is being made to ensure that we exceed the expectations of our attendees, whom we thank for their continued support and encouragement.”

Employing the theme “Building a Smarter World”, “Hexagon 2011” emphasizes the ways in which Leica Geosystems and its sister companies empower organizations to build a smarter world through industry-specific technologies that makes processes and infrastructures better, safer and smarter. More than 3,000 attendees are expected to attend “Hexagon 2011”.

To register and to learn more about Leica Geosystems @ Hexagon 2011, visit http://www.hexagonconference.com .

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Leica Geosystems – when it has to be right With close to 200 years of pioneering solutions to measure the world, Leica Geosystems products and services are trusted by professionals worldwide to help them capture, analyze, and present spatial information. Leica Geosystems is best known for its broad array of products that capture accurately, model quickly, analyze easily, and visualize and present spatial information.

Those who use Leica Geosystems products every day trust them for their dependability, the value they deliver, and the superior customer support. Based in Heerbrugg, Switzerland, Leica Geosystems is a global company with tens of thousands of customers supported by more than 3,500 employees in 28 countries and hundreds of partners located in more than 120 countries around the world. Leica Geosystems is part of the Hexagon Group, Sweden.