Crossing an Imagined Chasm
ARTICLE SPONSORED BY Trimble
Evolving technologies and expectations are blurring the traditional distinction between surveying and GIS
In the early years of GIS, many surveyors viewed the technology with caution—if not with a bit of disdain. The derisive phrase surveyors used to describe GIS, “Get It Surveyed,” was based on deep-rooted bias and often-inaccurate perceptions about the role and objectives of GIS data collection.
The crossover between the disciplines of GIS and surveying brings important opportunities for geospatial professionals. Readers of this column are likely in an ideal position to provide value, efficiency and comprehensive information that can benefit a wide variety of clients and applications.
In essence, the data collected by both GIS professionals and surveyors provide answers to the same basic questions: “Where is it?” “What is it?” “How does it relate to things around it?” “What about it is interesting or important?” In addition, both seek to address the most important question: “How can I get the information to people who need it?” They use similar technologies and work processes. And, in many cases, the information they produce is used by the same people. In spite of this, it’s not unusual to hear people refer to the so-called “Survey-GIS gap.”
The gap—if it exists at all—is closing rapidly. Rather than being competing disciplines, surveying and GIS are complementary actors that offer mutual benefits and opportunities.
Both disciplines use positions and attributes as primary data. The contrast lies in the differing emphasis on precision. Surveyors focus on precise measurement and positioning, while GIS requires detail and precision in descriptions and attributes. GIS attributes have little value without positions, and precise survey locations are nearly always accompanied by some sort of descriptive information.
In many cases the impetus to blend surveying and GIS comes from clients and end users of GIS data. Organizations are learning that increased precision in positioning can make their geospatial information more valuable and useful. For example, locating a gas shutoff valve in a flooded intersection can be slow and difficult. If the valve location is known only to within a meter or so, the field crew can spend precious time in a potentially dangerous situation. But with decimeter or even centimeter precision, the crew can find the valve more quickly.
Consumers of GIS data also want more than the 2D drawings and maps that were the hallmarks of early digital mapping solutions. The accuracy and precision needed to produce 3D deliverables with comprehensive attributes is a valued asset in many enterprises. However, traditional GIS technicians may lack the skills and equipment (high-precision GNSS and optical instruments) needed to produce the desired accuracy. As more GIS users come to understand the value provided by high accuracy, they are turning to surveyors to gather the precise data destined for GIS applications.
At first glance, this seems like a win-win situation: it can provide more work for surveyors and better data for GIS. But there’s a catch. Many surveyors are not trained to collect the information needed to satisfy the GIS need for detailed data. Missing information can result in costly revisits and misunderstanding between surveyors and GIS professionals. What’s needed is a way to tighten the interaction between data acquisition and data management and analysis.
Let’s look at three solutions to the problem. In one approach, survey-grade positioning solutions can be tied into the GIS workflow. This method simplifies the process of gathering decimeter (or better) positions and can be used by GIS professionals. By using software development kits (SDKs) or configurable solutions such as Trimble TerraFlex™ software, users can blend precise positions with GIS workflows and attribute collection. The method lends itself well to dedicated GNSS handhelds, as well as consumer-grade handhelds and a Bring Your Own Device (BYOD) approach.
A second approach in the field uses the Trimble Catalyst solution, an on-demand, software-based GNSS capability and service. Using Trimble Catalyst with an Android-based tablet or smartphone and a small, low-cost antenna, field operators can achieve up to centimeter precision in real time. The positions can be used by any app running on the device to provide simple, familiar workflows while working at a level of precision that is appropriate for their particular application.
A third method calls on the surveyor to gain specific knowledge about the information used in the GIS. This can best be accomplished by delving directly into the GIS database and creating workflows that capture all of the necessary data. To do this, surveyors can use Trimble Business Center (TBC) software to connect directly to an Esri database and extract object data and schema. This information can be used to automatically create the code libraries used by field surveyors with Trimble Access™ software. Then, when the survey crew calls up the code for a specific feature, the software guides the surveyor to gather all of the needed information. Aside from collecting more detailed attributes, the surveyor can operate within his or her existing workflows.
While matching survey feature codes to GIS needs isn’t new, the ability to automatically create feature codes from GIS schema is a significant step. It can save days or weeks of work to define feature codes. A GIS database may have thousands of different features, each with a dozen or more attributes. By connecting directly to the database, users can eliminate time-consuming manual entry and prevent errors or inconsistencies in definitions.
The links between surveying and GIS continue on the back end as well. When the survey field data returns to TBC, it is reviewed for accuracy and adjusted as necessary. Then, a single command writes the new survey data directly to the GIS database. When the GIS user refreshes the map in the ArcMap environment, all of the new data is there and ready for use.
This flow of information bypasses the usual process of exporting data from one package and importing it into another. Additionally, the GIS approach used by TBC removes many of the challenges faced by surveyors unaccustomed to collecting such rich attribute information. Each feature, complete with attributes and survey metadata, is available in the GIS database.
Demand for geospatial information will continue to grow as clients and the public become more savvy about the value and use of spatial data. As a result, surveyors should expect to be asked to provide more GIS-ready data and GIS professionals should plan to provide positions with higher accuracy than previously required. By adopting tools that allow survey solutions and workflows to interact directly with GIS databases and workflows, geospatial professionals can replace the gap with new business opportunities.
Modern software transfers survey-grade data directly to GIS databases. The GIS feature schema guides field crews in collecting detailed attribute information.