How Wide is a Point?

I have been reading a lot of banter about accuracy and precision which brings me to this “point”. Errors in measurements can lead to a wide range of issues in the survey profession. The sum of the potential error equals something I like to call “our error budget”. How big is your budget? First let’s look at the three types of errors that add to that budget.

Gross errors, also known as blunders. This type of error can be of any size or nature. They generally occur due to carelessness of the person doing the measuring, like writing down the wrong value or measuring between the wrong points. This error can be reduced or eliminated by using good procedures but transposing numbers is not uncommon.

Systematic errors are errors that can be mathematically modeled and hence corrected. They are caused by using a different mathematical model than that which exists in the real world. A good example of a systematic error is using the slope distance instead of the horizontal distance. This type of error can be reduced by using the correct and complete model.  An incomplete model will add to your error budget and cause the final measurement to be skewed.

Random errors also have an effect on the measurement but have no apparent cause. This type of error is the small differences between repeated measurements of the same quantity. They can be reduce or eliminate them from our measurements by statistical procedures. One example would be to create a mean value for a measurement to be used for a later measurement.

Now I’m no mathematician or statistical wizard, but I have been around the block a few times in the error buggy. Feedback from others in our profession has always been sharp to criticize a procedure but have also been faster to adopt a procedure once it has been proven beyond a reasonable doubt. This reminds me how some of the latest talks have pointed to the issue of “can scan data produce results that are more accurate than the published specifications of the scanner?”. Now for the answer… “YES” This is because there are many points that are being used to solve the position of a point. In other words we can use the power of averages to solve the final position.

The term survey accuracy can be confusing, misused and politicized especially when a layman is involved.  Although the fields of mapping and land surveying have benefited greatly from technology there is still the resounding question of accuracy in cadastral surveying based on measurements or law. There are accepted errors in the National Spatial Reference Systems (NSRS), the Continuously Operating Reference Stations (CORS) and the horizontal and vertical control stations maintained by the National Geodetic Survey (NGS). There are errors in the equipment, human errors introduced by the field surveyor, and accepted errors in the technology. But never before have we dissected and expected such precise accuracy in our profession until we knew we could obtain it. What was accepted as standard practices with traditional surveying in the past is now not good enough with current technology. The days of dead reckoning stood less criticism than .02’ laser scanner acquired data. Chaining has become obsolete which reminds me of a story about the old man that approached a survey crew. The old man asked the crew chief “do you still use a chain. The crew chief replied “sure whenever we get the truck stuck”.

Which makes me ask just how wide is a point?

Why Does a Bug Turn?

Did you ever think about the path of a bug? Why it alters its path? It crawls along its straight path then, suddenly without reason or provocation alters its course. Is it perhaps that he has traveled outside his environment?  Entomologists will tell you that when the bug grows weak they find it harder to exert energy to the path. When they are too weak they are stuck and frequently die shortly afterwards so they alter a course to return to familiar avenues of nourishment, not unlike the surveyors attitude with understanding how new technology can enhance their services. We all have our comfort zone that keeps us bound with limitations.  The educator has tenure, the union member has solidarity and the surveyor has the training to retrace others footsteps by analysis of evidence.

It is this guided path by the surveyor that makes us turn like the bug when faced with new technology. We saw it with the introduction of the total station and again with the advancements of GPS. Surveying is supposed to be the retracement of another surveyors work not a technology or math competition where a tenth of a foot is challenged. New technology is the focus going toward the challenge of whose math is better instead of embracing it by outing the principals and the art of surveying into play.

When I first started surveying we would evaluate found evidence right there in the field.  We would make a decision as to which set of found monuments we would use to best trace the previous surveyors path. With  GPS and Total Stations today’s surveyors can collect  coordinate values and suddenly you are in a virtual world. Now you are not boots on the ground evaluating the evidence right there right now but in a virtual world back at the office or in the truck which also enables multiple eyes to evaluate the field at the desktop. Terrestrial Mobile LiDAR Scanning (TMLS) is doing this to the topographic data collection routines in much the same way. It is taking the evaluation of the terrain shapes and break lines out of the field and into the office  and into a virtual environment. 

So, like a bug as we alter our course let’s not do it because we have become weak, lets embrace it to forge ahead new paths that make us stronger. When the bug eventually rolls over is it to die?

Do You Hear What I Hear?

     There is a new way to talk about transportation among surveyors and engineers. Now, I will be the first to admit that there is a huge personality difference between the two. Neither personality is bad thing, it is just a thing.  What the engineer says is often times not what the surveyor hears. Project communication goals must be clear from the beginning.  Why is the project being done? What is expected from the data? What is the time frame? These are questions that define the approach that the surveyor will take, whether traditionally or by using technology like terrestrial mobile LiDAR scanning (TMLS).  As the surveyor expands the tools of documentation that allow them to mine data from their survey at later time, up front communication will allow for a seamless workflow of sustainable data. As the additional applications of data expand with technology so must the communication. 

     The goals for each project must be clearly defined. Public mobility needs safe highways that can accommodate the traffic flow. The traveling public wants to get where they want to go quickly, without incident. And, they want to do it with one person in a car per destination. But don’t get me started on limited usage of HOV lanes and public transportation.  That is another BLOG. What the transportation industry is looking for is accountability, community based planning, and a performance driven plan. At the early stages of a project the engineer relays to the surveyor that data needed is usually needed for planning purposes.
     The second stage of the project requires a topographic survey usually including the utilities. So how do you get these two phases of a project completed without undue rework? A detailed written plan including time lines for phase deliverables and clear objectives. The traditional surveyor may or may not collect all the field work during the first phase, planning, but usually they just collect the data needed for the planning stage. The second phase, topographic survey for design, may be collected months or even years later. TMLS collects both phases quickly during the planning stage. This allows the engineer to look at different concepts using the point data during the planning stage and will eliminate multiple trips to the field by the surveyor to collect additional information whose value was not foreseen at the beginning of the project.
     So regardless if your project is utilizing TMLS or traditional survey, be sure to focus on the communication between the surveyor and the engineer, it will pay dividends throughout the project life cycle.

Happy Holidays

Outweigh the Outsource

There are pros and cons to outsourcing and the choice whether to participate can greatly affect organizational profits, employee morale and their productivity. These choices are made for different reasons and can cause conflicting loyalties. Current unemployment levels not seen since the Great Depression has many Americans feeling that Corporate America certainly isn’t doing its part to keep jobs “in-house”. Some of  the nation’s largest corporations — General Electric, Caterpillar, Microsoft, Wal-Mart, Chevron, Cisco, Intel, Stanley Works, Merck, United Technologies, and Oracle have cut their workforces by 2.9 million people over the last decade while hiring 2.4 million people overseas. This is eating away at our standard of living here in the US. No longer can an employee feel secure in their job like in the "old days" It also eats away at our tax base with no repercussions for outsourcing.

So what does that have to do with the surveyor? I continually hear how scanning technology is impeding on the survey profession yet,  most underestimate this new capability to handle more work and larger projects. Then what? Outsourcing drafting in the interim of automated processes is a viable option and there are many good, capable US companies that add that additional horsepower. US companies that understand regional issues, conversion issues with the international foot and metric verses US customary units. But, there are additional issues that encumber the work process when outsourcing overseas. Small as they appear, they can become one more issue to deal with in the life-cycle of a project.  Issues that become real are access, accountability, time differences and communication. The larger ramifications are security, inadequate bandwidth, national instability,  and of course the inevitable labor backlash publicity for your firm in this new “Buy America” age.

As a nation that is slowly becoming producers of nothing why would we now give away the virtual paperwork? What will our son's or daughter's work environment look like? Will they have the professional opportunities that you had?

Reference:

Zaid Jilani (2011, 19 April),ThinkProgress, Top "US" Corporations Outsourced More Than 2.4 Million American Jobs Over the Last Decade, retrieved July 21, 2011 fromhttp://www.truth-out.org/top-us-corporations-outsourced-more-24-million-american-jobs-over-last-decade/1303196400

Mother Nature Inside Looking Out

There’s an old weather saying by surveyors, “rain before seven… done by eleven”.   In my days of field surveying we welcomed a rain day.  It meant the day off!  Speed of data acquisition acquired from TMLS technology today allows us to virtually topo at the desktop, rain or shine. 

In March, the Terrametrix team ventured to American Samoa to document 126 miles for telecommunications placement. Temperatures are 88 – 76 degrees every day with a chance of rain somewhere on the island.  You can’t scan in the rain when the surface is shiny as the laser refracts off the surface into space. So, when it rained we just moved to the sunny side of the island. But, we still got an unusual time off due to weather.

American Samoa sits tropically west between Hawaii and New Zealand, or as we learned, in the tsunami Pacific Ring of Fire. In all my weather related experiences as a surveyor; tornadoes, blizzards and thunderstorms, the tsunami warning was the first time I was concerned about my elevation. It was not a day off on a tropical island to look forward to.  Consider, we had just completed several days of scanning and targeting areas of the remaining ruins from the 2009 tsunami that killed 22 residents in American Samoa's capital of Pago Pago.  Seeing this destruction first hand, plus watching CNN reports of the recent Japan earthquake, gave renewed respect for the power of Mother Nature. So, when the Pacific Tsunami Warning Center issued a tsunami warning for a wide area in the Pacific following Friday's 8.9 magnitude earthquake off Japan's east coast you can bet a day off wasn’t my first thought.

Japan is now working to rebound from its devastating earthquake and tsunami in rebuilding the region of Tohoku using the technology of Google mapping and modelling tools. It is clear that the collaborative technologies of TMLS and Google are laying new groundwork in the planning process that also reduces risks from future disasters. Integrated civil design and engineering software ideally suited to civil engineering and transportation projects like Bentley’s In-Roads, GEOPAK and TerraSuite’s plug-in to MicroStation can be used on all types of civil projects, by users with different levels of expertise, for a range of project needs. Because these products were developed and are supported by practicing civil engineers and professional surveyors they are more than a rainy day application.

Adapting to the Elements

To say that we surveyors come out of hibernation during the winter thaw is a mild overstatement of our role.  After all, the nature experience is why we chose this profession.  For me, it is these first two weeks in June in the Midwest that has special “back to nature” meaning for me.  This is a time when you can still shoot line through the trees.  Brome grass and other cool weather foliages are green before ripening and still laid down due to the snow pack. It is a time prior to the bugs and being outside temperature-wise is a pure pleasure.  Where did that go this season in Nebraska?

After enduring our strange spring, with high temperatures ranging from 96 degrees to 52 degrees since May 9^th, we now seem to be pushing the 90’s for the past week. This of course has brought with it torrential rains, flooding and severe tornadic thunderstorms.  April and May flew by as well with varied seasons as we travelled across the country for rail, highway and bridge projects.  What we learned as scan technicians and what we knew as surveyors is that the equipment you have must be as committed to the elements as the crew that runs it.  This season we have adapted new features and eliminated the “not so easy on your back features” to our scan truck to make the seasonal challenges more manageable. Although the StreetMapper360 system we have fitted with additional cameras weighs only about 200 pounds and it’s installation could be done in a few minutes, lifting it onto the roof became a process we wanted to avoid.  It now sits securely in the covered bed of the scan vehicle and hydraulically lifts through a skylight in the topper. Once on project site the scan system can be ready for data collection in just 2 minutes. Having the equipment out of harm’s way during destination traveling is more gas efficient (our green initiative) and less obtrusive during down time.

Another item we have found very useful is the adaptability of the StreetMapper 360 system which allows us to put the system on many different platforms, ie, boats, hy-railer etc, for a wider use of capabilities. Track time is valuable. This mobile platform makes “on-the-track… off-the-track” logistics more mobile. It is one rail certified Terrametrix scan technician collecting data and their track master driving a hy-railer.  On at a crossing… off at a crossing… at project start up and end. Terrametrix has taken the best of what was proven in the past, evaluated the issues that were cumbersome to speed and accuracy of the project and still maintained it’s versatility.

I guess if you think about it, we have created our own weather system inside the truck where every season can be whatever the AC or heater is set at. Every day at Terrametrix is now June!

Accuracy Lessons Learned

Benjamin Franklin, the surveyor said, “If you don’t remember your mistakes, you are destined to repeat them”.  I often ask myself, “What lessons do we need to remember as surveyors?” I have 33 years of my own to evaluate.  Now, as a proponent of terrestrial Mobile LiDAR surveying Scanning (TMLS), I understand the importance of this hindsight. After all, surveyors by nature are not animals of change. The common mind-set has been that the profession will fragment further to specialization driven by technology. The 5% of leading edge surveyors bring along the remaining percentage over an extended period of time. I am amazed at the number of surveyors who now utilize a GPS system like we used to break out the level, tape and transit. GPS has proven to be a truly incredible change in the work flow and physical effort needed in the field which equates to huge man hour savings. 

My survey mentor told a story about how he had performed a lot survey for a home owner. When he went to collect his fee of $100.00 the home owner said…

 "$100.00, but you were only here for a short time and you only had to set one corner".

My mentor replied, "Well, it was $5.00 to set the corner and $95.00 to know where to set it".

Knowledge is powerful and in today’s world of digital gadgets it can be a whirlwind that my mentor would not only embrace but excel in. 

 Did GIS change the role of the surveyor? Did GPS change the role of the surveyor? Will TMLS change the role of the surveyor? The answer to all of these questions is no, but it did! (Spoken like a surveyor.)  The truth is… lately as I travel across America speaking to surveyors and engineers, I am finding a greater acceptance for this technology because of its faster and safer way to collect spatial data. Surveyors are slowly embracing TMLS, not as a way to phase out their job but as a way to expand business and increase opportunities.   In fact, the past two months Terrametrix has been exposed to more than 4,000 surveyors at various conferences and workshops.  The tide is changing, after all how do you teach a computer spatial recognition?

What I am finding, however, is the questioning of accuracy, again and again and again. How accurate is it?  It’s a valid and important question and the answer is… survey grade accuracy. It’s discerning to me that until now, until TMLS provided the transparency of repeat data, what a traditional surveyor shot in the field was considered “gospel” accuracy. The difference is we can see the variance of data in TMLS. The field book was seldom questioned, however, you have to consider… send that same rod and instrument crew out again then tell me how close will they be on their second pass? Now add traffic. Add the GPS error budget. Add total station error budget.

The confusion of TMLS accuracy is not whether or not it is trusted data, the confusion lies in is the transparency of data accuracy.  It has been proven through field trials that TMLS accuracy is survey grade… 8–13mm, and just like GPS or a total station you have to use the correct procedures to obtain survey grade data. How precise is your rodman at 600,000 points a second?