Professional Surveyor Magazine Current Edition

Software Review: Trimble R8 GNSS + Trimble Access

by J. Craig Brewer, PLS

Trimble’s R8 is a lightweight, compact, fully integrated GNSS receiver loaded with the most advanced positioning technology. For this review I used the R8 with a Trimble TSC2 data collector running Trimble Access software. I have experience using the R8 receiver but have not used the Access software before this review.

While reflecting on this review, I’m amazed at how far surveying technology has advanced in only the last 40 years. I’m sure some of our readers can remember when pulling chains and turning sets on transits was an everyday work method. I can only imagine what type of tools we will be working with 40 years from now.

Weighing just over three pounds with battery, the R8 contains the receiver, antenna, UHF radio, Bluetooth, battery, and 57-megabyte internal memory. The amount of memory sounds small, but it’s enough to hold several weeks of raw observables. The chip set inside the receiver has 220 channels and can track up to 22 satellites. It is capable of receiving signals from GPS L1, L2, L2C, and L5. It also receives Glonass L1 and L2. Trimble intends to use signals from the Galileo satellites once they are operational and can currently receive Galileo test signals.

The R8 has a seven-pin lemo connector on port 1 and a nine-pin connector on port 2. There is also an antenna connector for use with the internal UHF radio. I used Bluetooth connections so didn’t need these.

Setup

Setting up the R8 is quick and painless. I turned on the R8 and placed it on the pole, then turned on the cell phone and put it in my pocket. Once I turned on the TSC2 and ran the Access software, the R8 and cell phone were connected via Bluetooth. In just a couple of minutes I was connected to a network and receiving sub-centimeter corrections. The time saved by not needing to search for benchmarks and run miles of level loops was enough to put a big smile on my face.
The receiver, data collector, and pole weigh just over eight pounds. Weight becomes extremely important after you have carried something all day.

The R8 can operate as a mapping-grade receiver, providing sub-meter positions, or as a survey-grade receiver, providing sub-centimeter positions. You may be wondering, “why not use survey grade positions all the time?” Sub-meter position corrections are much less complex than those required for sub-centimeter positions. This allows positions to resolve more quickly. Also, I have found that sub-meter positions can provide more reliable results than sub-centimeter positions in areas with multiple obstructions, such as tree canopy. If you are working on a GIS asset mapping project in an area with multiple obstructions, sub-meter might be a better choice.

This data collector is used in Georgia and South Carolina and has information for two networks loaded. I picked eGPS from the list and had a fixed sub-centimeter VRS solution in just a few seconds. (eGPS Solutions, Inc. is the largest privately owned GNSS GPS base station network in the United States. Their network covers all of Georgia and Florida and extends about five miles off each state’s coastline.)

Most surveyors I know are choosing to use RTN corrections rather than a dedicated base receiver. There are several advantages. Network use eliminates the time spent setting up a base station and allows you to cover more ground in less time. You also save the expense of purchasing a base receiver and are not exposed to the risk of having the base stolen. The largest limitation is cell phone coverage. If you are working in an isolated area, network corrections may not be an option. As cell phones become more widely used and providers expand the networks, this is becoming less of a problem.

Using Access Software

Once I had everything running, I dove into the TSC2 and the Access software. Just like everything Trimble develops, Access is part of a complete workflow solution. Their goal is to maximize productivity and efficient work flow with minimal effort. I don’t always prefer products that are proprietary in design, but this approach is working well for Trimble. One big advantage is that you know exactly whom to call should you need product support. I have been bounced back and forth between product support departments in the past when using third-party applications. If you are trying to get a job completed, that is the last thing you need.

Trimble Access software not only runs the R8 and other Trimble receivers but also works with Trimble and most other total stations. You can begin a job in Access using the R8, then switch to a total station, and keep working within the same job. This eliminates the need to transfer data between devices and reduces the number of power chargers you need to maintain.

Trimble Access software combines field-survey tools with web-based tools and creates a real-time connection between the field and the office. It is built using their Survey Controller software as its base and is scalable.

The base level of Access software contains standard functions for performing both GNSS and conventional surveys. It also contains internet connection settings. The menus are arranged to minimize time spent moving between menus looking for settings and functions. Some of the specialized modules that can be added include Roads, Mines, Tunnels, and Monitoring. These can be purchased or rented if you need them only occasionally.

Under the measure menu I selected continuous topo and began to walk. I heard a ground shot being stored on the distance interval I had selected. After collecting a few hundred shots, I checked into a control point. Wow. No matter how many times I do this, the speed and accuracy still amaze me. GNSS is just one tool among many that we use to complete our work; it may not the best tool for every job we do, but GNSS provides a huge competitive advantage.

Online Connections

Another capability that can be added to Access is online services. These services provide a connection between the field and the office. Information can be transferred instantly using Access Sync and is also securely backed up on Trimble’s off site servers. Data can be synced at any time. Field surveyors can sync their file literally within seconds of taking their last shot, and then office processing and drafting can begin. Jobs can be reviewed and any additional information can be gathered before the crew leaves the site. If a layout revision is set to the office, the new files can be uploaded to Trimble’s server and synced onto the data collector. The time savings and efficiency increases are obvious. (A subscription to Trimble’s Connected Community is required for these online services.)

The Trimble Connected Community is a web-based service that allows you to access and share information with multiple team members. It allows users to sync and store data and also includes project management and communication tools. These include calendars, links, blogs, images, quick notes, and forums. Information is available in one central location from various users and workgroups; events and schedules are easily tracked; and project history is secure and readily available when needed.

I hope this review has given you an idea of what this equipment is capable of. To learn more, contact your Trimble dealer or click here. Click here to see a video of Trimble Access in use.

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J. Craig Brewer, PLS is a principal and director of surveying at KRI Engineering, Inc., a civil/survey consulting firm in Savannah, GA.

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History Corner: The Beginnings of Satellite Geodesy

by George M. Cole, PLS, PE, PhD

Part one (in the January issue) tracks the progression of the first tests and use of artificial satellites for geodesy, a forerunner to today’s GPS. Part two continues the history, with early notes from the field.

As the North American satellite triangulation program progressed in the mid 1960s, it became obvious that, with a higher-flying, larger satellite, a truly worldwide network could be created, including all continents and major islands. Such a network would eliminate the troublesome discontinuities in mapping systems that existed over the oceans and at most national frontiers. However, such an effort was obviously beyond the reach of a small agency such as the Coast and Geodetic Survey.

Therefore, a “sales” presentation was made to the Department of Defense and NASA. The concept was of obvious interest to Defense because this was at the height of the Cold War. Accurate targeting of ballistic missiles required accurate knowledge of the positions of both the launch site and target on a common reference system. Therefore, a joint program was developed, with the Coast and Geodetic Survey retaining responsibility for technical direction of the field operations and data processing.

NASA launched a balloon-type satellite, PAGEOS I, for the use of the program on June 23, 1965. Shortly thereafter, survey parties began traveling around the globe, carrying elaborate cameras and precise timing synchronization systems. Using twelve observation teams, field operations continued until 1971 and resulted in a network of 45 stations.

Unlike our modern GPS observations, each satellite triangulation occupation lasted normally for several months because repeated photographic observations of the satellite had to be made simultaneously with those being made at other stations. Furthermore, those observations had to be made when the satellite was sun-illuminated and the skies clear at each of the widely spaced stations working together.

To provide scale to the triangulation network, the project included the measurement, by use of EDMs, of on-the-ground distances, or baselines, between several pairs of stations. Two of these baselines were located in North America, one in South America, two in Europe, one in Africa, and two in Australia. The project was an international effort with cooperation by all of the nations in which stations were located. Some nations provided observing teams and some participated in measuring the baselines.

Time Synchronization

Time synchronization of the observations was an especially challenging part of the program. Each observing unit was equipped with a precise time synchronization system, and those systems were synchronized monthly by someone traveling to each station with a portable electronic clock synchronized to the U.S. Naval Observatory’s master atomic clock. Between monthly synchronizations, any drift of each unit’s time system was monitored by comparing the frequency output of the system with very low frequency (VLF) radio transmissions.

The electronic clocks used for time synchronization were fairly sophisticated, and there were many interesting episodes with airport security personnel when traveling with these ticking electronic devices. When flying with the more accurate, but larger, cesium-beam-type clocks (atomic clocks), an extra seat on the aircraft would have to be purchased for the clock because of its physical size. Fortunately, as the program progressed, various active satellites were launched with atomic clocks aboard. In coordination with the Applied Physics Lab of John Hopkins University, a means of using signals from those satellites for time synchronization was developed.

Interesting Times in the Field

Because it was necessary to occupy some relatively remote locations to achieve the best geographic configuration, field operations for these projects sometimes presented exciting challenges. I was fortunate in serving on field parties at several interesting locations. My first assignment was with a field party occupying the station on the island of Antigua in the British West Indies. There, I was able to skin dive and bask in the warm tropical sun in my time off.
Immediately following that, however, I experienced thermal shock after being assigned a party that occupied a station in the small, Arctic Eskimo village of Cambridge Bay, on Victoria Island, Northwest Territories, Canada. We were flown to the village on a Royal Canadian Air Force C-130 cargo aircraft that landed on the ice of the bay. As soon as the aircraft landed, the crew opened the rear ramp of the aircraft and began rolling out our equipment trailer and unloading all our supplies onto the ice.

In less than a half hour after landing, the plane had taken off, leaving us standing there in the thirty-degrees-below-zero darkness, on the ice of the bay in our new parkas and bunnie boots, with all our equipment and supplies scattered around us. I must confess to a few moments of abject fear as the aircraft took off that October, scheduled to return to pick us up not until the following April.

During that assignment in Cambridge Bay, our four-person team lived in a wood-frame-supported insulated tent, equipped with a “honey bucket” for a restroom. Frequently, several lemmings visited inside the tent, and we had to dig out of the quarters through snow drifts after storms. Therefore, it was not the most comfortable living conditions. It was difficult to work for long periods outside, so by adopting local custom, using snow blocks, we constructed a good-sized expansion to our equipment shelter as a work area (Figures 1 and 2).




It was an exciting assignment. The village’s population at that time was about 200. Although it was a fairly barren area, there was an abundance of wildlife such as Arctic fox, seal, ptarmigan, and occasionally musk oxen. Also, there was active ice fishing on the Bay. While there, we stumbled upon the remains of the ship Maude, once used by the great Norwegian polar explorer Amundsen. Parts of it were still visible above the ice.

There were also opportunities to accompany villagers on seal hunting trips via dog sled and to participate in the village curling league in a homemade rink in an abandoned Quonset hut. While there, I learned to speak a passable version of the Eskimo language. The villagers’ name for us was oplogiyanik kongiatit kaomayonik, which translates as “bright star gazers.” Therefore, during the Christmas season, we mounted an illuminated star on top of our camera dome when not in use.

Following Cambridge Bay, I had field parties in several other locations, including Goose Bay Labrador; Keflavik, Iceland; and Halifax, Nova Scotia, before being assigned to the Washington office to assist in the coordination of the program. Although I continued to travel extensively to our various stations in my new position, I missed the more intimate knowledge of the geography of an area gained by several months of living there. The program included some exotic places and involved a wide variety of geographic conditions and in extremes ranging from 125 degrees in central

Africa to the 55 degrees below that we experienced in Cambridge Bay and even colder temperatures in Antarctica, so it was a challenging and exciting program.

Evolution

Yet, within a decade after this tremendous effort, the network and technology was obsolete. Satellite technology evolved to allow development of the Global Positioning System that provides the capability for position determination to a far greater precision in seconds instead of the several-month observational period associated with the satellite triangulation process. Furthermore, GPS uses a relatively small instrument as compared to the cargo-planeload of equipment used in the earlier program. Nevertheless, the satellite triangulation program did represent a significant, and adventuresome, advance in man’s understanding of the Earth’s size and shape that set the stage for the later improvements of the space age.

Participation in the program also gave me an appreciation for the ease which we now determine geographic positions with today’s GPS system. Each time that I make a GPS observation, I cannot help but remember how it was back in the “good old days.”

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George M. Cole began his career as a commissioned officer in the Coast & Geodetic Survey (now the NOAA corps). His career has also included service as the state cadastral surveyor for Florida and many years in the management of private surveying and mapping firms. Dr. Cole is currently an adjunct professor at Florida State University.

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Feature: Constellations Merge

By Geoffrey Phillippe, Cheryl Kung, and Steve Wilson

The last two years have seen a shift in the precision GPS equipment market as high-precision GPS receiver manufacturers are moving from GPS-only systems to multi-constellation (GNSS) systems. During this time, we have also seen GLONASS emerge as a credible constellation worth consideration as a component in the surveyor’s arsenal. But while combining GLONASS with GPS indeed improves survey results, it pays to understand the facts and nuances behind this complex situation.

GLONASS (GLObal’naya NAvigatsionnaya Sputnikovaya Sistema) is a globally available satellite-based navigation system operated for the Russian government by the Russian Space Forces. From the end-user standpoint, both the U.S. GPS and Russian GLONASS systems work in similar fashion, as both systems use a constellation of globally distributed satellites orbiting the Earth in precise orbits. The user determines their distance from an individual satellite by measuring the time it takes for a radio-frequency transmission to travel from the satellite to the user’s equipment. Position is then determined by triangulation based on the distance from each satellite currently in view.

The following table provides a comparison between the performance of the GPS and GLONASS systems.



While GPS and GLONASS share high-level similarities in function, some critical differences affect end-users:

• There are twice as many active and healthy GPS satellites as GLONASS satellites. It is feasible to use a GPS-only receiver globally but not a GLONASS-only receiver.
• The clock and orbit accuracy of the GPS satellites is significantly better than that for GLONASS satellites. Therefore, a GPS-only solution is much more accurate than a GLONASS-only solution.

If GPS is better than GLONASS, then why use both? The answer comes down to a comparison between ideal and real-world conditions. If the world were ideal, there would be no obstructions and lots of well-positioned satellites in view at all times. However, in the real world, trees, buildings, hills, and other obstructions can block satellite reception. As a result, the receiver does not track all the satellites in view, and the ones it does track may be arranged such that any position errors become magnified.

While tracking enough satellites to compute a position is important, it is equally important that the satellite geometry provide for a high-quality, robust solution. The effect of satellite geometry on position accuracy is expressed using the term PDOP (position dilution of precision). PDOP is measured on a unitless scale from 1 to 20, as outlined here.


    
Under ideal conditions, with a clear view of the sky with 10 to 12 satellites in view, the PDOP for a GPS-only solution could be in the 1–2 range. The challenge is that due to buildings, trees, and urban canyons, there are often fewer than six visible GPS satellites. At these times, the PDOP drops from a usable number of 2–3 to a barely acceptable level of 5 or 6. Suffice it to say that no one wants to stake his or her reputation (or legal liability) on “let’s take a shot” quality of measurements.

What do you do if you have only a GPS-only receiver and a poor PDOP? You basically have two options. You send your team out to lunch and hope that when you come back in an hour, the GPS environment is better. Or you go old school and break out the total station, theodolites, and transits. Either way, you start spending—and sometimes wasting—time, energy, and money to capture five minutes of data.

GNSS system manufacturers know that it is not just the number of satellites tracked but the quality of the position measured by factors such as PDOP that drives the adoption of their equipment by the professional surveying community. If a manufacturer can provide a better PDOP in real-world conditions than the next competitor, the better the perception of their equipment will be by end-users and the more sales they
can garner.

A Hypothetical Example

How does GLONASS help me do my job better? Let’s assume you are working on a sunny, clear day in Los Angeles, California during mid-January 2010, doing a precision survey close to a set of trees, as shown in Figure 1. With an unobstructed view of the sky, the GPS-only satellite visibility provides usable PDOP <3 for most of the day, as shown in Figures 2 and 3.

However, in the hypothetical scenario, the outcrop of trees has knocked out 40 percent of the sky in one direction. This significantly reduces the number of visible GPS-only satellites, increasing the PDOP to unacceptable levels, as illustrated in Figures 4 and 5.

By adding GLONASS satellite tracking to the solution, the overall GNSS satellite visibility improves, yielding a usable PDOP (e.g. 3–4) for most of the work day (Figures 6 and 7).

Testing a Real-World Example

A series of dynamic partial blockage tests were conducted in the Los Angeles area between July and September 2009 using a NavCom Technology SF-3050 GNSS StarFire Receiver. This high-precision, multi-frequency GNSS receiver is capable of tracking all available public GNSS signals including:

• GPS – L1, L2, L2C, L5
• GLONASS – G1, G2
• Galileo (GIOVE-A, -B) – E1, E5b
• SBAS – WAAS, EGNOS, MSAS

The SF-3050 rover antenna was mounted on the roof of a GNSS test van (Figure 8) and driven through the test course at speeds up to 25 meters per second. The SF-3050 was configured as an RTK rover, receiving RTCM RTK corrections from a RTK base station located about 26km away. For a dynamic truth reference, a competitive GPS receiver integrated with a military-grade IMU was configured in RTK-aided mode and received RTCM code corrections from the same base station.



The partial shading test course (Figure 9) consisted of a ~3500-meter stretch of Madrona Avenue in Torrance, California. The street has a number of tall trees (10 to 12 meters) in the median as well as on either side of the road. The trees block portions of the sky up to 60- to 70–degree elevation, making it difficult for a GPS-only receiver to maintain tracking.

The main purpose of partial shading testing was to evaluate the impact of using GLONASS to aid GPS for DGPS modes such as RTK, test the receiver’s ability to recover quickly in difficult environments, and ensure that it did not report solutions grossly in error during the difficult sections

The course was driven three times, interwoven with static periods when the van was parked in an open-sky area to ensure that the SF-3050 test receiver had fully reacquired all satellites in view. As illustrated in Figure 10, the SF-3050 typically tracked six to eight satellites when configured in GPS-only mode. With this number of satellites, the 3D position jumps (delta North, East, Up – dNEU) were frequent and sizable, often exceeding 15 meters (Figure 11).

In contrast to the GPS-only results, the SF-3050 configured in a GPS+GLONASS tracking mode routinely tracked 12 to 14 satellites over the test course. In addition, the periodic position jumps were far fewer in frequency and lower in absolute magnitude (e.g. 10 to 15 meters), as illustrated in Figures 12 and 13.

Clearly, GLONASS is not a panacea that can solve all the problems a professional surveyor may encounter in the field with a GPS or GNSS receiver. The best and most high-tech equipment on the market will not replace solid fundamentals, good technique, and a bit of common sense.


















However, the integration of GLONASS and GPS by a multi-frequency, multi-constellation GNSS
receiver can provide a number of benefits to the professional surveyor:

• ability to work in environments where obstructions may partially block the sky,
• less vulnerability to changes in GPS satellite visibility (e.g. GPS brownout), especially when operating in high-precision modes such as RTK,
• improved PDOP and ability to rely on the quality of the data, and
• greater operational time in the field and increased efficiency by not having to wait for that perfect time to take measurements.

All these benefits translate to professional surveyors achieving greater use of their GNSS equipment. This means a faster return-on-investment for the GNSS equipment, being able to do more in less time, and having better margins or cost-competitiveness. These capabilities are critical as the surveyor market responds in these turbulent economic times.

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Geoffrey Phillippe is GNSS product development manager for NavCom Technology.
Cheryl Kung is GNSS product marketing and communication specialist for the company.
Steve Wilson is GNSS products business manager at NavCom Technology.

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Rules of the Game: Avoiding a Complaint by Effective Communication

by Knud E. Hermansen, PLS, PE, Esq.

In this article’s examples, names have been deleted and in some cases wording and facts changed to preserve confidentiality.

Surveyors have often called me to admit they are seeking my advice because a complaint has been filed against them with their state board of licensure (in the examples here I refer to “the board”). Being charged with a complaint of improper practice or behavior is usually a stressful experience.

Competent and incompetent surveyors alike can expect to go through the experience during a lifetime of practice. In fact, my experience suggests that complaints are made more often against competent surveyors than the incompetent surveyors. I surmise that competent surveyors are often of firm conviction based on the knowledge they have faithfully performed their duties in a competent manner. The surveyor’s conviction leads to such strong self-assurance and self-advocacy that the surveyor fails to realize that his or her opinion, when placed in the heated environment of a boundary dispute, is like gasoline on a fire: it causes an explosion that engulfs the surveyor.

Also among competent surveyors are those who perform surveying services without fault but often are not as faultless when operating the business, especially when communicating with the client and the client’s neighbors.

Conversely, I have seen incompetent surveyors move a corner pin around at the request of the client or neighbor with no conviction as to the propriety of their actions. However, the neighbor or client, seeing that his or her demands are being met, lacks any inclination to file a formal complaint although the surveyor’s incompetence must be obvious even to these laypersons.

In almost all cases, there is some lead-up to a person making a complaint. Surveyors can often avoid a formal complaint by recognizing the signs of an irate or frustrated client or neighbor and taking steps to prevent or alleviate the irritation or frustration. If a surveyor perceives there is an irate or disgruntled neighbor or client, the surveyor should keep written notes of events, actions, conversations, and contacts.

Whenever possible, the surveyor should respond to the irate or frustrated party promptly, in writing, combining both tact and reasonable rationale. The time spent responding to an irate party may reap many benefits, the biggest being the prevention of much time, effort, cost, and stress resulting from a formal complaint to the licensing board.

Here is an example letter.



The surveyor should always communicate to the irate party in a manner that assumes the communication will eventually be examined by the board (or court). The board could form their first impression of the accused surveyor after reading the surveyor’s communication.
The next article will provide advice on preparing for the hearing.

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Knud Hermansen is a surveyor, an engineer, and an attorney. He teaches surveying at the University of Maine and operates a consulting firm providing services in professional liability, title, land development, boundaries, and easements.

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Editor's Desk: Surveying’s International Flavor

We all know that surveying transcends political and geographic boundaries. We measure land and water no matter where it may lie. But two things have come to light recently that accentuate the international flavor of surveying.

One of our feature stories gives a rundown on GLONASS, the Russian satellite positioning constellation. Many GPS equipment manufacturers offer products that can receive GLONASS signals, and surveyors have begun to use the signals to augment GPS, particularly in situations where overhead canopy or lack of available satellites makes GPS by itself less than fully effective. We attempt to eliminate some of the confusion surrounding GLONASS and show how it can be integrated into surveying procedures.

We often hear of the progress non-U.S. systems such as GLONASS, Galileo (Europe), and Compass (China) are making, to the point that we take them for granted. But remember that not long ago, we were hostile enemies with Russia and other communist bloc countries in the Cold War and threatened to wipe each other off the face of the Earth with our nuclear arsenals. Perhaps more than anything else, satellite positioning has brought, or at least revealed, a new post-Cold-War era of international cooperation, as we all enjoy the benefits of these constantly improving systems. Both GPS and GLONASS were originally developed for defense and space purposes, and it’s great to see them spun off for use in civilian applications. Wouldn’t it be nice if they could help us bring peace to places like Iraq and Afghanistan?

As for the other thing, many sectors of our society have responded to help victims of the recent earthquake in Haiti, and those in the surveying and mapping profession are no exception. Actually, it turns out that maps are a sought-after commodity in Haiti. In a post on Google’s Blogspot, David Smith, a surveyor in Scranton, PA and vice president and director of geospatial information technology for Synergist Technology Group, says, “Currently, useful maps of Haiti are few and far between.” He says OpenStreetMap has been able to rapidly respond and provide robust updates to include capturing data about things like collapsed buildings. “I would encourage anyone who has time to contribute to get involved in this effort—editing can be done directly in OpenStreetMap.”

Equipment and software vendors have gotten involved as well. In its newsletter, DeLorme says it has applied its mapping and GPS tools to the crisis. “Data technicians developed a GPS-accurate, routable road and street map for Port-au-Prince and other affected areas.” It adds, “Products are now being used by emergency personnel and relief organizations to map the extent of the destruction, help navigate around the city of Port-au-Prince and beyond, assist in the distribution of much-needed supplies, and plan for the slow rebuilding process.”

I’m sure many more surveyors around the world have responded to this need. Kudos to anyone who helps out with this massive recovery effort.

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Feature: New Workflows Increase Profit

By Terry Bennett

What is my business strategy for the future? How do I stay competitive? What does the future hold for my employees? As surveyors and business owners, we often ask ourselves these questions whether we are a sole proprietor or head of a large company with many offices and employees.

Because of the technological advances in GPS, GIS, geomatics, surveying, and building information modeling (BIM) software, we are constantly re-tooling and updating our equipment portfolio to keep pace. But are we doing the same with our business process and strategy? For the most part, many of us use similar hardware and software both in the field and in the office, so how do we turn that consistency into a competitive edge? And how is laser scanning going to redefine surveying and all AEC businesses over the next five to seven years?

Although laser scanning is still new, expensive, and complicated, it’s already having a major impact on traditional surveying and opening new fields to surveying and measuring expertise. For instance, laser scanners are now used for factories, forensic analysis, media and entertainment, historical preservation, and transportation. And the list of applications will only grow as the technology becomes more common and less expensive—similar to how GPS has been widely adopted as the price has dropped.

For a few key reasons, companies are beginning to look at laser scanning for buildings over other techniques. First, with the complexity of buildings, no other technique can capture the same level of detail as the laser scan. Second, laser scans provide for significantly higher degrees of accuracy for construction documents. Ultimately, this combination of detail and accuracy allows the creation of a model well suited for communicating intent, efficient collaboration, and presentation purposes.
 

Process as Important as Technology

While terrestrial laser scanning holds great interest as a technology, its true power comes when that technology combines with new modeling and analysis tools and BIM workflows. Together, they are breathing new life into old infrastructure by modernizing as-built information to a current state. Energy conservation and sustainability are top priorities in the United States and many places around the world today. Efforts are under way in many states to reinforce that focus, with an increasing number of local governments offering fast-tracked permitting to projects that are green, or sustainable, in approach.

When applied to existing buildings, bridges, dams, railroads, and even subways, laser scanning exterior and select interior locations produces a point cloud of the structure that can be used to create 3D models. These models, in turn, can be used in a BIM process. This integrated approach allows professionals to use coordinated, consistent information to explore a specific project’s key physical and functional characteristics digitally from design to construction, before it’s built.

By capturing the geometry and characteristics through laser scanning, the resulting model can be used in a BIM process to conduct many aspects of energy performance analysis, retrofit approaches, iterative design options, detailed construction sequencing, and support contracting processes. These range from basic models to energy and investment-grade audits to implementing measures that enable better decision-making.

BIM helps users create a model so they can visualize and simulate the performance, appearance, and cost of renovations on any piece of infrastructure. Recent reports indicate that the world’s population is moving to urban centers, growing from 53 percent today (or 3.6 billion people) to 70 percent (6.3 billion people) by 2050. Pressure on the global urban infrastructure will rise dramatically. To redesign infrastructure in dense urban settings where this mass migration is heading, designers need very detailed and accurate as-builts of what exists.

Today, surveyors have the opportunity to step up to that business challenge. Whether it’s the billions of dollars spent greening our buildings or fixing roads, bridges, and waterlines, the density of the sites will require the clarity and resolution that laser scanning provides. The resulting digital model that surveyors can provide engineers, architects, or building owners is a valuable part of the process and one that reaps great advantages over the traditional processes and general CAD drawings.

Determining physical properties by using laser scans with BIM allows you to more quickly and more accurately analyze and assess the performance of infrastructure. With this data in hand, you can better evaluate, compare, and rank the environmental and financial affect of proposed renovations. Possessing this deeper understanding of the relative performance of the infrastructure portfolio, stakeholders can prioritize an overall infrastructure modernization program and focus on those projects that have the greatest affect. However, technology may well be the easy part, while the change in process and new thinking needed to take advantage of the technology is the hard part—the business side of the equation.

Becoming Model Centric

For many of us, changing the focus of our business processes requires a change from being application-centric to model-centric, i.e. BIM. This proves true as we look at the proliferation of point clouds and masses of 3D information ready and waiting for a BIM workflow. What does this mean? While the survey department focuses on the software best suited for a data collector or total station, the engineering department is contemplating which design software and wireless devices for inspections are best.

Here’s the key: Have the two really communicated with each other from a process standpoint? When you have models becoming the commodity for design, how does the transfer of models between professionals (surveyor to engineer or architect) change the workflow? While each department may efficiently perform its own tasks, this type of department- or task-focused approach leads to restricted and regimented workflows that make it difficult to innovate even with new tools and technologies. Not to mention that numerous agencies may need to review the information and require custom reports that also need to be re-run with each change. This creates critical pain points where the information must be created again and again in different formats.

When looking at a process change such as going from standard survey deliverables to contributing laser scanning point clouds to a BIM workflow, consider the following aspects. Like before, understanding the process of BIM—what it does, what existing processes it will allow us to do differently, and what it will enable us to do that we haven’t before—is vital. Think back on the reluctance to the first 2D CAD systems. When 3D modeling systems appeared, there was even more resistance. This same resistance to change holds true for BIM solutions. These create and operate on digital databases for collaboration and manage change throughout those databases so that a change to any part is coordinated in all other parts, and they capture and preserve information for reuse by additional industry-specific applications.

A formal implementation strategy is an essential component of any successful laser-scanning-to-BIM deployment and must go well beyond a simple training and rollout schedule. It should address the workflow and organizational changes inherent to BIM. Laser scanning and BIM open many doors for designers, but to make it all work, you must have models generated from the get-go with reality-based data. That’s why laser scanning and the data it creates are critical. More than a point cloud, it is a 3D starting point for design. An implementation strategy also needs to address how the new solution will initially coexist with existing 2D drafting or 3D modeling applications.

Wholesale abandonment of these legacy design applications is impractical and often ill advised, but as the implementation expands, the strategy may also include plans for the phased retirement of legacy systems. Firms should look at how the BIM model can be accessed by related applications. Specifically, look at the work you need to accomplish today and match that to the tools you put in place today. For firms that handle large projects, your implementation strategy should include guidelines for creating and working with large models (additional hardware requirements, techniques for reducing model complexity, etc.).

Because BIM represents a new approach to design and not just the implementation of new supporting technology, firms should pay close attention to the makeup of the transition team, ensuring they comprise both technically forward-thinking people and senior leaders. Because change sometimes disrupts ongoing operations, it needs to be addressed head-on, prior to implementation. Education and awareness about BIM are key tools when tackling the natural resistance to change, particularly in firms where organizational structure and disparate locations make communication more complicated. Select the right project to start with, something your firm already knows how to do, so there’s only a single dimension of learning. Gathering these statistics can substantiate the promised ROI of the system and help garner support among the “show-me” members of the firm.

The Way Forward

Comprehension of these complex technologies is essential, and as surveyors we are called upon to speak a common hardware and software language with other AEC professionals, most notably civil engineers. As professionals, we need to step back and look at the bigger picture. We need to focus on not only what we are charged with—resolving land boundaries and providing the data framework for the building of infrastructure—but how best to redefine design and construction to leverage the extensive knowledge we have and the services we can provide.

What should you look for as you review technology, solutions, and systems for your business? Look for companies that want to be your business partner, not just providers of technology. And look to those that have a solution and a model-centric approach, one that can leverage your laser scans and models throughout the entire design and construction process.

They are the ones that will give you the best chance of evolving and leveraging all the technology we have at our disposal. We owe it to ourselves, our customers, and the future of our businesses. Some key aspects to consider: Information exchange between land development professionals on a project team is a given, but the degree of that exchange and ease at which it is accomplished is not. Traditionally, this breakdown in communication of design information is one of the leading causes of project overruns and delays. The ability to mitigate communication breakdowns to a minimum through business process improvement (and not just focusing on operational efficiency) is a critical step in decreasing liability exposure. Increasing accuracy and coordination between departments and different elements of the infrastructure work process will reduce errors and redundancy of information, all with the goal of decreasing the risk of business failure by avoiding high fixed costs or over-staffing in periods of high demand. Laser scanning and models in a BIM process have proven to address this.

At the top of the checklist for a smooth deployment of laser scanning and a BIM solution are these critical success factors:

• develop a sound, comprehensive implementation strategy for each,
• assemble the right team, those that comprise both senior and technology progressive people—you need advocates who will garner respect,
• select a suitable starting project, and
• be prepared for the inevitable resistance to change that a revolutionary approach like laser scanning and BIM will provoke.

At some point, we all will face making a change in our business strategies. To prepare for the future, we must be ready to change and know why. Change is never easy, but it is the one constant of business. So in thinking about laser scanning, it’s not what you are looking at that is key (just a technology), but what you see—a way to differentiate yourself and your firm, to become a key player in the move to BIM and the rebuilding of our world’s infrastructure.  

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Terry Bennett, PLS, LLS, LPF, LEED AP is senior industry manager for the Civil Engineering & Construction AEC Industry Group at Autodesk.

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Aerial Perspective: Faster, Easier, Better

by Adam Evans and Andrew Stott

Geospatial professionals today must frequently deliver situational awareness and site-specific geospatial data, quickly and efficiently, in the form of orthorectified images. Aerial remote sensing is an increasingly important tool for obtaining this data. In the past, the costs of operating traditional large-format aerial cameras have significantly reduced the profitability of smaller aerial mapping surveys and corridor projects. Moreover, the expense and systems expertise required to integrate and support all of the required components was, for many agencies and companies, a barrier to engage directly in airborne mapping; airborne mapping was just too complicated and expensive.

Today, because of new turnkey, all-in-one solutions, this is no longer true. Lightweight, ruggedized, and highly maneuverable, new airborne mapping solutions are designed to operate efficiently in even the most demanding conditions, providing timely, low-cost, and high-accuracy results for projects of all sizes. They include all required components, such as digital metric camera, flight management system, GPS-inertial system, and complete software workflow. A turnkey solution such as the Trimble Digital Sensor System (DSS), built by Applanix, a Trimble Company, uses “direct georeferencing” to deliver complete, accurate ortho products within hours of landing—without the need for time-consuming and expensive ground surveys.

Direct georeferencing is one of the most significant applications of new technology in airborne mapping. This approach combines the technologies of airborne GPS for determining the position of the plane and camera with the abilities of an inertial measurement unit for determining the rotation of the camera. Direct georeferencing allows the creation of highly accurate aerial mapping products, in most cases without the need for aero triangulation and its associated time and cost. Designed to operate efficiently on even the smallest of aircraft, these all-in-one solutions using direct georeferencing are cost-effective, practical, and easy to use.

Turnkey airborne mapping solutions are proving to be efficient and effective for many applications. For example, large earthworks projects (any moving of earth, such as the digging of a canal) require accurate volumetric survey for the purposes of project monitoring and billing. Airborne and mobile mapping solutions allow accurate, non-intrusive measurements of moving earth, enabling users to manage their project with greater accuracy and accountability.

Case Study: The Arabian Canal in Dubai

The Arabian Canal is one of the largest developments of its kind in the world and one of the most complex civil engineering projects in the Middle East. Its developer, Limitless, is a global, integrated real estate developer, specializing in master-planning of large-scale, mixed-use projects and conceptualization and execution of waterfront developments.

On-going construction of the canal involves several challenges, including the need to accurately measure the amount of earthwork moved each day. A total of one million cubic meters of earthworks is moved every day, or about 5,000 to 10,000 trucks-loads.

Project managers have to accurately track three critical project requirements: progress against plan, as-build against plan, and invoice approvals. They require state-of-the-art technology for monitoring the earthworks; orthophoto maps of the construction area for planning and visualization, with ground sample distance of 10 cm (max), and ortho-accuracy at 12 cm RMS; and point measurements for volume calculations of cut/fill areas. The methods have to be very fast and effective because they needed accurate measurement of the topography of 100 hectares within hours.

The challenge: For smaller projects, earthworks monitoring such as this is often carried out using traditional survey equipment such as total stations or GPS, or more recently with 3D static laser scanners that produce highly accurate point clouds from which geometric measurements can be made. However, for this large area and given the constraint that measurements could be made only between shift changes (approximately 1.5 hours every 12 hours), traditional static survey methods would be too costly in both equipment and personnel and would not meet the required timelines.

Additional problems for a project of this size and scope include requiring many crews and sets of equipment for covering the large area and the many datasets that need to be merged, raising the cost and complexity. It also requires the manual setup of equipment, which is time consuming.

Mobile mapping technologies require higher capital but are cost effective because of their many advantages, including:

• very fast data acquisition,
• single pilot operation with associated low personnel costs, 
• the fact that a single set of equipment covers a large area, 
• that only one or two data sets need to be merged for quality control and for delivering very high reliability for data accuracy and precision, and 
• safer working conditions for staff.

The solution: Limitless decided to use two mobile mapping solutions instead of static surveying techniques, as mobile mapping represents an optimal convergence of digital photogrammetry with other positioning technologies such as laser scanning, GNSS, and inertial. Mobile mapping reduces the cost and the schedule risk by increasing efficiency.

The two platforms chosen were a helicopter-based Applanix DSS, integrated with LMS-Q240 lidar for producing orthomosaic color-image maps, and an Applanix land-based system for oblique imagery. Both produce directly georeferenced, high-resolution 3D terrain models in the form of laser point clouds and filtered digital surface models. The land and airborne data sets complement each other to produce full coverage and high-accuracy, high-density 3D terrain modeling of the dig with built-in redundancy.

Methodology: The development area is divided into four phases, each about 25 to 35 square kilometers. Using the airborne mobile mapping system, four hours flying time is needed to cover phase one, which is about 25 km2. This operation is done bi-weekly. The land-based system is used to cover the occluded area.

Out of both systems, a DEM is created accurately with a 10-cm precision. Within one week of conducting image/lidar scans, accurate topography as a final product is delivered. During a daily data acquisition scenario, the airborne system covers an area of 25 km2 with four hours of flying, while the land system covers 100 hectares mapped in an hour. Weekly 3D mapping products have been successfully delivered with average height accuracy of 6 to 8 cm, with standard deviation of 3 to 6 cm and RMS of 8 to 9 cm.

Results: The graphics below illustrate some of the system deliverables. Figure A shows the mapped area with our system (e.g. more than 4,500 images), with the produced pixel size precision is 10 cm. Figure B shows the active excavation and filling sites within phase one of our development. Figures C, D, and E illustrate area one progress level with 3D modeling and a color-coded image. Figures F, G, and H illustrate another active site that reached -6.5 meters below mean sea level, with 3D modeling and a color-coded image. It is a 40-meter-deep dig within the canal route, which illustrates the resulting excavation.



Traditional earthwork monitoring surveying techniques impose a significant risk for timeliness of data acquisition and associated costs. Mobile mapping represents an optimal convergence of digital photogrammetry with other positioning technologies such as laser scanning, GNSS, and inertial, reducing both the cost and the schedule risk by increasing the efficiency of the collection process. Mobile mapping systems provide high accuracy and short turn-around compared to traditional techniques.

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Adam Evans is DSS product manager and Andrew Stott is a technical writer at Applanix in Richmond Hill, Ontario, Canada.

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