As imaging in general explodes, questions naturally arise about the role of surveying. Ted Knaak, president of Certainty 3D, spent a lot of time at his group’s user conference talking about how control can be added after data had been collected.
While there are as many technical discussions as there are methods and technologies (and even equipment types) to accomplish the data capture, the basic issue is when to add control. The simple answer is, when it’s needed.
That sounds a bit flippant, but it is actually true. Knaak’s comments are derived from the kind of work he does for departments of transportation. In those cases, a state DOT may have a specific project where survey-grade data is needed but at the same time, it must collect hundreds (if not thousands) of miles of data that will be used for other purposes. Those longer stretches of road may be targeted for GIS data, which doesn’t require the same level of control as the construction projects.
Given the cost of establishing control, Knaak’s recommendation is to collect the data in a way that allows control to be added later. The process for the construction project doesn’t change, but where the GIS data is being collected there may be some adjustments to the specifications established at the beginning of the project and the quality control and quality assurance during the process. With good data and tight quality control, the need for expensive field work to add control to some of the portions of the data may be avoided or at least reduced. This should translate to projects other than the highway examples Knaak uses.
The role of the surveyor in establishing control is pretty clear. The question is, does everyone get the message? There’s a difference between accurate and precise. Capturing accurate imagery may be fine for the GIS portion of the highway example, but precision is needed for the construction element. The only legal document that guarantees that precision is the one signed by a licensed surveyor.
Manufacturers who serve the survey and geospatial professions understand the differences and work hard to avoid confusion. The rise of simple, fundamental imaging tools, and especially unmanned aerial systems, is fogging up the lens a bit for those outside the profession who are asking for and using these images. With the final deliverable in mind, it is important for surveyors to help data consumers understand where control is needed, how it is established, and whether control can be added later to the data.
The answer isn’t, “control is needed everywhere all the time.” It may be the answer is that control is needed in more places than the user has been led to believe. It’s better to establish that up front and have more usable data collected cost effectively than to do the same work twice.
Surveyors need to understand the nuances of how to connect the dots for the end users, if you’ll allow a pun. That may mean spending some time learning more about the extraction and processing side of data collection.