Whether we like it or not, technology is dragging us forward. In the surveying community we have had to deal with disruptive technology changes just as often as the rest of society, maybe more. The interesting thing about surveying measurement science is you have to be aware of the complete history or you may find yourself in a legal entanglement.
For instance, when retracing an existing boundary survey we find units of measurement involving paces, chains, poles, steel tapes (and even cloth tapes), EDM’s, total stations (manual and robotic), and finally GPS. It doesn’t stop there though. Now we have static laser scanners and imaging GPS systems and a number of hand-held devices ranging from GPS receivers with built-in imaging and laser pointers to purely hand-held image based systems using photogrammetry. Not to be left out, traditional aerial photography and photogrammetry have long held a place in the surveyors tool box for historic retracement and evidence.
Obviously not all of these can be used to (precisely) locate boundary lines, but that is just one part of the surveyors problem. Location of all above ground features is also a very big part and can be very time consuming. This will be the focus of this discussion.
The "modern" approach to surveying at the moment usually involves quickly occupying points on, above, below or near the features of interest using GPS (probably RTK). Depending upon the project area a vehicle is often utilized to rapidly move from point to point. No matter what, the crew spends a lot of time walking. On most projects there are often areas that cannot be measured with GPS due to skyward obstructions and in those cases the total station is used. This is all facilitated by using one data collector to switch between a GPS unit and a total station. This technology has drastically changed how field procedures are performed, how long it takes, how much it costs, crew size, reliability and more.
Since many of our readers are probably not very familiar with what a typical lot survey looks like, lets take a quick look at one.
A survey is more than just lot or boundary corners. In fact, it has to be quite comprehensive often showing not only the streets, powerlines, buildings, poles, and driveways but drainage and all other pertinent above ground information. This information is important to the land owner, realtor, buyer, and developer as well as the local governing body including the tax collectors office. Using a total station with a two or three man crew this sort of data can easily consume several hours just to collect the field data. With an integrated GPS and total station the time and man-power can be reduced. One important point to note is that to get the information necessary somebody normally has to occupy the point of interest with a receiver or a reflector. However, even this can be overcome using an imaging system, reflector-less system, or static laser scanner more equipment.
How does a typical boundary survey begin? Normally a surveyor will receive a call, email, or visit, with a request to have a parcel surveyed at a certain address. Not many years ago, this then required a field trip to the site to perform a brief reconnaissance mission to help build an estimate. Today, with the advent of Google Earth and other similar utilities, the surveyor can get a glimpse of what he/she will be facing before one arrives at the site. Still, you never really know until you get to the site what to expect.
What if the area to be surveyed was part of a large subdivision?
How about a small lot with a high wooden privacy fence and a small backyard? Perhaps its a lot with a solid canopy of trees? Maybe its a lot with partial tree cover and multiple buildings? It could be a very neglected home with low, thick brush (usually poison ivy or poison oak!) around almost all of the features of interest. These are all very typical scenarios in lot surveying. When preparing a bid or readying a field crew, these considerations all contribute to what equipment is necessary.
Now lets turn our eyes to the future. Lets consider using a mobile mapping system. It is very doubtful that a system with a $500,000+ purchase price will be employed to do a $500 to $1500 lot survey. The ROI just isnt going to be there. Its not just the equipment cost that makes this prohibitive though, its the software as well. A company can find itself quickly paying upwards of $50,000 just to get the job done with more than one piece of software. Add to that the training and it becomes pretty apparent why lot surveying with a mobile mapping system is unlikely. However, often times struggle and perseverance can yield great return.
Lets change the picture a bit. Lets bring in a mobile system that is priced at $100,000 and requires no special, dedicated vehicle and only one person to operate. It can be mounted on a car, truck, or ATV, carried on a backpack, pushed on a cart or pulled on a wagon, or even mounted on a UAV. Would such a system make an impact on lot surveying?
Tune in next time as we begin our investigation into lot surveying with Snoopy. As always, keep an eye on www.lidarusa.com for our latest developments. You never know when something special might happen!