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/

Jamie Gillis Joins Geomatic Resources

Irving, Texas – February 9, 2011 – for immediate release Jamie Gillis, RPLS, PLS has joined Geomatic Resources LLC as a Technical Support Specialist based at Geomatic’s Solutions Center located adjacent to the DFW Airport in Irving. He will provide technical support for Leica Geosystems GPS, Robotics, Total Stations, and Data Collection to Land Surveying Professionals in North Texas and Oklahoma.

Jamie brings a strong background in the surveying industry, and his high level of professionalism and survey knowledge to the Geomatic Resources team. His experience covers a wide range of surveying duties. His background includes serving as Instrument Man, Survey Assistant, Party Chief, Offshore Survey Technician, Project manager, and Professional Land Surveyor. His early surveying experience includes performing numerous field assignments in Nova Scotia, Canada. Recently, he has served as RPLS/ Project Manager for a number of natural gas gathering pipeline projects, oil & gas lease and location surveys, boundary, topographic, and hydrographic surveys and has been involved with offshore positioning and metrology, monitoring & logging surface & sub-surface positioning data in the Gulf of Mexico.

Jamie is a Registered Professional Land Surveyor in Texas and Louisiana, and is very active in the Texas Society of Professional Surveyors and the American Congress on Surveying and Mapping. He holds a PBC in Geographic Information Sciences from Texas A&M University in Corpus Christi. He also received a BA in History and Political Science from Dalhousie University in Halifax, Nova Scotia.

“Jamie will be taking on the key role of supporting our existing customer base on all survey products and will be helping with our ongoing sales efforts. We hope you share our excitement in adding such a well respected and knowledgeable person to our staff. Please join us in welcoming Jamie Gillis to Geomatic Resources” says Rodney Walsh, President of Geomatic Resources LLC. Jamie can be reached via email at jg@geotx.com

About Geomatic Resources
Geomatic Resources LLC is one of the largest independent distributors of Leica Geosystems products in the United States, serving North Texas and Oklahoma from a sales, rental, service, support and training center adjacent to the DFW airport in Irving, Texas. Geomatic provides Surveying Professionals with state of the art GPS, Robotic, Total Station, Digital Level, Machine Control and HDS Laser Scanning solutions as well as a full range of Supplies and Accessories. For more information about Geomatic Resources visit www.geotx.com or email rw@geotx.com or call 817-691-5328.

GPS Reference Networks

One of the mistakes we see companies make is they forget to be Boy Scouts (always be prepared).  In an effort to save a little money we often do not get back ups such as extra batteries, cables, etc…  This cost cutting usually ends up costing you more than you saved when everything goes down.

The same thing applies to working on GPS Reference Networks.  We assume that this simple solution that saves us thousands of dollars is a perfect end all answer and while it is great it is not the total solution.   We forget the variables involved such as the range of the receiver from the base, cellular connections, and let’s face it the base is being controlled by someone else.

When the company I worked for sent a GPS crew out to survey they had a back up.  When a standard crew went out, they had a back up.  I remember working in Louisville, KY one winter after a nice snow had come through and the temp was well below freezing.  We took 2 extra batteries for the total station which was a good thing because the old batteries did not hold up so well in the cold.  With about an hour of surveying left to do we had gone through the first two batteries and the third was starting to show signs of failing.  Several hours drive back to the office and a client wanting their job done that day did not leave us in a good spot.  My old friend and the Survey Manager (who was much smarter than me) chuckled when I started to hop in the truck to head back to the office.  He came around the truck with a level, a rod, and a tape.  We finished the job that day.

It can be expensive to have these extra things, but when you need them the savings is almost unmeasurable.  Reference networks are no exception.  The idea of being able to work miles from a base (over 20 miles in some cases) without having to ever set the base up or figure out the position is huge and something I would encourage more people to look in to.  The problem is that we get too relaxed and buy a single rover and have no back up plan.  When we reach the limits of the range of the network, the end of cellular coverage, or the network goes down you are essentially shut down and that is not good.

What do you do?  Go to plan “B”.   With so much new technology coming out right now we are finding great deals on used older technology GPS receivers.  We are also seeing products like the Altus APS-3 that can operate as a network rover, or as a base/rover.  For anywhere from $5,000-$12,000 you can have a back up plan that over time can save yourself down time, lost production, and most importantly money.

So do yourself a favor and be a Boy Scout….always be prepared!

Trimble Adds CAD Point Creator Software to its Building Construction and MEP Portfolio

New Trimble Point Creator Office Software Provides the Ability for Contractors, Engineers,
Detailers, and Architects to Create 2D and 3D Points for Field Layout within their Native CAD Application
NEW ORLEANS, May 5, 2010 — Trimble (NASDAQ:TRMB) today introduced the Trimble® Point Creator Software for contractors, engineers, detailers, and architects supporting the building construction industry as well as mechanical, electrical, and plumbing trades. The application, available in two versions—Trimble Point Creator and Trimble Point Creator Pro—provides a platform where Computer Aided Design (CAD) users can create 2D and 3D points easily transferrable to and from a Trimble LM80, Trimble MEP, Trimble TS Series Total Stations as well as other total stations. The application is compatible with popular CAD platforms such as AutoCAD, Bricscad, and ZWcad.

The announcement was made today at the Associated Builders and Contractors 2010 Educational Conference, the association’s annual gathering of merit shop contractors, subcontractors, material suppliers, and related firms throughout the U.S.

As the construction industry continues to push the utilization of Building Information Modeling (BIM) practices for cost savings, overall efficiency, and project data collaboration. Trimble Point Creator Software enables users to create 2D and 3D points directly within familiar CAD platforms—and then easily share with field layout software/controllers. For the project manager utilizing CAD drawings for information as well as point creation for field layout, Trimble Point Creator works seamlessly inside CAD software, simplifying data preparation for layout.

By incorporating common industry standards and file formats such as .cnx, .dwg, .dxf, .csv, and many others, Trimble Point Creator Software supports the transfer of points to and from a Trimble LM80, Trimble MEP, Trimble TS Series Total Stations as well as other total stations on the market today. And with overall data integrity playing a key role in the effectiveness of deploying BIM throughout a project, Trimble Point Creator is designed to retain each point�s attribute data, even when imported from a field controller file.

The introduction of Trimble Point Creator Office Software to Trimble’s Building Construction portfolio demonstrates a continued commitment to leveraging technology to deliver solutions that provide a strong return on investment for a broad range of contractors and trades on the industrial, commercial, and residential construction jobsite.

Trimble Point Creator and Trimble Point Creator Pro Software are available now through Trimble’s worldwide Building Construction Distribution Network.

About Trimble’s Building Construction Business

Trimble’s Building Construction Division is a leading innovator of productivity solutions for the building construction contractor. Trimble’s solutions target site prep, general, concrete, mechanical, electrical, and plumbing contractors on large and small commercial, industrial and residential jobsites. Trimble is focused on delivering solutions that tightly link office based process and information with the field crew—including taking Building Information Modeling (BIM) and other design data to the field for highly accurate positioning and layout of foundations and mechanical, electrical, and plumbing systems. Trimble solutions provide a high-level of process and workflow integration from the design phase through to the finished project—delivering significant improvements in productivity throughout the building construction lifecycle.

About Trimble

Trimble applies technology to make field and mobile workers in businesses and government significantly more productive. Solutions are focused on applications requiring position or location—including surveying, construction, agriculture, fleet and asset management, public safety, and mapping. In addition to utilizing positioning technologies, such as GPS, lasers and optics, Trimble solutions may include software content specific to the needs of the user. Wireless technologies are utilized to deliver the solution to the user and to ensure a tight coupling of the field and the back office. Founded in 1978, Trimble is headquartered in Sunnyvale, Calif.

Fixed Height Tripods for GPS

With a total station the height of the instrument is usually measured to the height of the “eye” or the center of the optic which makes it relatively simple.  With GPS there is no optic, only an imaginary plane that is used to determine elevation by figuring the distance from the ground to this plane.  Ok, maybe it is not imaginary, but the phase center measurements are neither physical positions nor stable points.

The phase center is variable on any GPS receiver based on directional signal information from satellites. These variations affect the antenna offsets used to connect the measurement to the position being recorded.  To handle this, the National Geodetic Survey calibrates each receiver model creating a measurement between the receiver phase center and it’s antenna reference point (ARP).  When we plug in the height of the receiver to our data collector we key in the measurement from our point to the ARP.

Some receivers have “measure points” on the receiver other than the ARP that are easier to get to for measuring.  You can then either do the simple math to reduce the height from the measure point to the ARP, or in some cases the data collection software already has that equation built in so you only enter the distance from the point to your measure mark.  Some units such as the Leica receivers have a tripod hook that has been calibrated to their ARP.  This allows the user to affix the “hook” to the base of the receiver, pull the tape to the point and know the number read includes the distance from the end of the tape to the ARP.

The simple answer here is to do the same thing you do for your rover.  Use a fixed height base.  There are a few options available such as the Fixed-Height GPS Antenna Tripod with Collapsible Center Staff from SECO Manufacturing (SECO PN: 5119-00).  This particular tripod features a collapsible center staff with twist locking mechanism that rotates 360° to check calibration of plumbing with a 10-minute vial, and quick release & twist locking mechanisms on the legs. It is dual graduated and adjusts to three heights: 2 m, 1.8 m, and 1.5 m. It collapses to 50 inches (127 cm).

I highly recommend these for use with the Altus receiver and have a few clients using them with their Sokkia and TopCon GPS units as well.  For more details on how to use this tripod visit SECO’s website http://www.surveying.com/tech_tips/details.asp?techTipNo=13.