The Evolution of the Data Collector
Electronic data collection is so commonplace today that it is an exception when it isn't used. Early surveyors spent a lot of time in the field, sometimes even to the extent of processing their data and making maps in the field. Rising labor costs drove technological advances that minimized crew size and time in the field, yet the current crop of data collectors brings some of that data processing back to the field. Over the years, many factors have shaped the surveyor's handy data collector into an indispensable tool.
Early Days of Electronic Data CollectionIn the late 1970s and early 1980s, some of the European manufacturers of theodolites attempted their first designs of total stations. Included in some of these designs were also the first attempts at electronic data collection. Methodologies varied, but some of the novel ideas that manufacturers experimented with included Wild's (now Leica Geosystems, Norcross, Ga.) magnetic tape and Carl Zeiss' (now Trimble, Sunnyvale, Calif.) magnetic bubble memory modules. Interestingly, both of these solutions were onboard the total station, rather than a separate handheld device with keyboard, display, software memory and power. Other devices followed these initial attempts at data collection, and emphasized simple capture of the measurement data (usually slope distance, vertical and horizontal angles). Often a number and code used to describe the point could be added to the record. Special records were used to indicate instrument location, backsight location, height of instrument and target.
In 1983, Sokkisha (now Sokkia, Olathe, Kan.) introduced the SDR1, quickly followed in a year with the SDR2. Sokkia used the registered trademark "Electronic Field Book" for this technology to reflect a change in philosophy in electronic data collection. Rather than create an electronic version of a "bucket" into which the data was thrown to be later organized and analyzed, Sokkia developed the ability to do a number of in-field computing tasks with the SDR. These functions included immediate reduction of slope distances to their horizontal and vertical components, calculation of three-dimensional coordinates of observed points, area calculations, field staking calculations from any point, curve layout, and traverse calculations and adjustment. By offering these features, the technology restored to the field certain tasks of analysis and computation that had moved to the office. Customers saw this as an improvement in their ability to control the quality of their surveys. It allowed them to recognize problems in the field as they had in the days of pre-electronic instrumentation when data was reduced and even computed and plotted in the field.
Soon thereafter a number of software vendors added their products to the data collection mix. Some provided the "electronic bucket"; others such as Tripod Data Systems (TDS, Corvallis, Ore.) and Surveyor's Module Inc. (SMI, now Eagle Point, Dubuque, Iowa) provided in-field computing and analyzing tools. By the mid-1990s, almost all major instrument manufacturers either sold their own data collection software or obtained it from third parties--even though some of this software carried the manufacturer's brand name. Wild introduced a proprietary hardware product with its GRE series of data collectors, as did Hewlett-Packard (HP, Palo Alto, Calif.).
The most significant aspect of the SDR series and its counterparts from other manufacturers is that they were introduced as a hardware and software package separate from the total station. Most of the time, the data collector was only usable for collection of data from a total station. Sometimes it could be disconnected and used to enter notes similar to those a surveyor might write in a paper field book. Manufacturers have called data collectors by various names, sometimes to reflect their functions, and sometimes to differentiate them from other technologies. A number of manufacturers began using the term "field controller" to reflect its role at the nexus of the combined technologies used by the surveyor and its ability to do much more than simply collect data.
In most cases, the data collection hardware was made by parties other than the manufacturer of the integrated product. TDS and SMI, for example, relied on hardware platforms from Hewlett-Packard. Sokkia's data collector platform came from MSI Data Corp. (Costa Mesa, Calif.), a manufacturer of handheld data collection products for a wide variety of industries. The hardware was generally made for applications other than surveying, but somehow the data collector vendors found ways to adapt the hardware for surveying. Resistance to moisture, dust, vibration, shock and drops was often weak. Manufacturers resorted to add-on packages, boots and complete repackaging in a different case to address some of the surveying market's issues. Additionally, in the early days, battery-backed (volatile) RAM was commonly used to hold data. Lack of care in understanding the procedures for protecting the data from loss resulted in having to return to the field to survey again--which was not always possible. Gradually, the volatility of the data reduced. First, additional back-up batteries were included with the hardware and then the user-friendly flash EPROM technology was incorporated, which is still in use today.
The keyboards of the early data collectors varied considerably in effectiveness for field operation. The degree of moisture resistance, imperviousness to dirt, dust and debris and the correct tactile feedback were not consistently featured with the hardware, particularly if it had not been originally designed for the field. Displays were initially text only and single line. Before graphics and color were introduced, multiple line displays were a significant enhancement.
Onboard Data CollectionIn the mid-1990s, manufacturers saw an opportunity to give their customers an opportunity to "get it all from one source" by adding data collection capabilities to the total station itself. This was made possible by improvements that occurred in the microprocessor component technologies. One benefit of the combined unit was reduced cost. Another was that the surveyor no longer had to operate a separate device that could potentially be forgotten and left back at the office. Additionally, the integration eliminated the cable and its proneness to hardware failure, along with the way it tethered the user to the total station.
After the combined data-collector-and-total-station appeared on the market, many different incarnations of software interfaces were introduced and sold. Some worked better on the total station, whereas others worked better in a separate handheld device. For manufacturers, a disadvantage of combining the data collector and total station in one unit was that a customer's preference for another software interface affected sales. This was somewhat overcome when third-party software providers of popular data collectors, such as TDS, integrated their software inside the total station.
Back to External Data CollectorsWith the introduction of RTK GPS in 1992 by Trimble, the world of data collection suddenly changed. GPS manufacturers knew that the acquisition of RTK products by potential customers was going to be limited by the ability to properly annotate the survey work done in the field. Many new functions, such as support of geoid models, datum conversions and plane projections needed to be supported in a handheld device coupled to the RTK GPS receiver.
The operational parameters of GPS put new demands on portable handheld devices used as controllers. Some of the parameters that were different from those for total stations included: no line of sight required to the base station, long distances from the base station (10 km in the early days), all-weather operation and 24-hour surveying. Renewed energy was put into developing software and hardware platforms that could meet these new demands.
The push to support RTK also brought about questions from the user community regarding the interoperability between total station and RTK technology. Manufacturers realized that they had to solve this problem to convince their customers to move from a one-tool survey crew (using a total station) to a two-tool survey crew (adding RTK GPS). Further software development was required to solve this issue, and refinements to this process continue today.
Since the most desirable solution for customers was a device that could be used to collect data interchangeably with a total station and RTK GPS, most manufacturers returned to the external data collector model. If the device was "stuck" inside the total station, lower levels of interoperability with RTK resulted. So, although market pressures initially moved data collection inside the total station, RTK began to pull it out into a separate device again. This eventually gave birth to the "parents" of the current crop of data collection devices.
In this new iteration, the principal issue to be resolved was the large number of cables used to connect the data collector to the GPS receiver. The receiver often served as the conduit to the digitally controlled radio device, which served as the data link to the base station. Extra batteries, the antenna connection, etc., added additional cables. Cables were eliminated in the rover by combining the receiver, antenna and battery in the same housing and by adding Bluetooth technology to handle the two-way communications with the data collector.
The Geodimeter brand of total station by Spectra Precision (now Trimble) took a unique approach to data collection hardware. Spectra's data collector was a removable device shaped like a keypad for a total station. It could be transferred to the rover pole and used to control RTK GPS data collection. The memory and software moved with the removable keyboard and thus accomplished the same goals, but in a more integrated fashion than conventional handheld data collection devices. Trimble continues this approach as one of its data collection solutions today. For example, the Trimble CU controller is designed as an integrated keyboard for the S6 total station and can be attached to the robot and RTK poles.
Robotic InfluenceThe unique requirements of robotic total stations have also influenced data collection hardware. The robotic total station was a response to customers who needed faster, cheaper and more accurate ways of getting things done. Theoretically, the robotic total station can be effectively run by a single person. This makes a data collector useless if it is built inside the total station or connected by wire. At a minimum, the operation of a robotic total station required the interface for data input (keyboard, touchscreen, etc.) and output (display, audio signals, etc.) to be at the prism pole and wirelessly connected to the total station. In response, manufacturers elected to combine the interface, computer and software into one device. The result is a handheld data collector with a pole mount that frees both of the user's hands.
Today's Data Collection HardwareBecause of the need for interoperability between total stations and RTK GPS, a standalone or transferable data collector has become the optimal solution. It detaches from the prism pole and attaches to the RTK GPS rover's pole. Currently, this solution dominates the market. Data collection devices support interfacing with a minimum of two kinds of technology (total stations and RTK GPS). Many data collectors support other surveying technologies as well, including digital leveling, static GPS and laser scanning. Because of the sheer volume of data produced by static GPS and laser scanning methods, this data is often stored in another memory device rather than inside the data collector, although control information and other data may be stored in the data collector. Notably, Leica Geosystems did not follow this route and elected to have separate data collectors for its total stations and RTK GPS, but with an identical operating interface to facilitate interoperability and data compatibility. Leica's design philosophy has been that the two operating environments are sufficiently different so it is better to optimize the data collector hardware separately for each. But even Leica offers third party data collector hardware that switches between RTK GPS and total stations.
Today's data collector hardware comes from major manufacturers of surveying instrumentation and software and hardware manufacturers, as well as major manufacturers of portable computing technology (e.g., Juniper Systems of Logan, Utah; Two Technologies Inc. of Horsham, Pa.; and Hewlett Packard). In some cases, manufacturers of instrumentation provide users with third party software and hardware solutions to data collection as well as their own to provide maximum flexibility, especially when crews mix brands of tools.
Carlson Software (Maysville, Ky.) chose to introduce several versions of Two Technologies' hardware platforms for its customers. According to Bob Bailey, director of data collection, "The HP-48 was such a popular unit that we introduced the [Carlson] Explorer with a keypad that reflects about 40 percent of the keys of the HP-48, giving the customer the ability to use keys or the touchscreen."
XYZWorks (Roswell, Ga.) also uses products from Two Technologies, but again custom-designs its offerings to fit the needs of its software and customers. The variations even include the physical keys and accessories, such as the battery-charging and data downloading facilities provided with the units.
Some software vendors rely on platforms from multiple vendors. Eagle Point offers customized platforms from both Two Technologies and Juniper Systems. "A large number of our DOT clients require the data collector units to last through a four- or five-year replacement cycle and, consequently, are willing to pay more for the military specs of the SMI Allegro, and then we have our smaller surveying shops that want performance, but are willing to compromise ruggedness to have a more affordable system that our SMI Jett supplies," says Lance Andre, product manager for the SMI product line at Eagle Point.
Among the unique combinations available today are offerings from Topcon (Livermore, Calif.) and Magellan (formerly Thales, San Dimas, Calif.). Topcon's GMS2 was designed primarily for GIS data collection. It has a built-in GPS receiver for this purpose, as well as a digital camera. However, the GMS-2 can also be used with Topcon's total stations and adds flexibility for surveyors alternating between surveying and GIS data collection. A similar concept is used with Magellan's MobileMapper CE device, but without an integrated digital camera.
Physical FeaturesThe hardware used by surveyors today is a far cry from the hardware of the 1980s. In all cases, the current collectors have been designed for outdoor environments, and resistance to moisture, dust, vibration, shocks and drops has improved.
Attention to the user interface has improved through increasing the size of the displays. Today, many of the data collectors provide a one-quarter VGA screen at a minimum. As a result, instead of simply supporting text and icons, graphics including the display of maps and photographs are possible. A color display is standard in many cases. Many of the screens use touchscreen technology, so the software interface is a combination of hardware keys and virtual keys or buttons on the screen. Styluses are not mandatory but handy for operating some of these touchscreens. While most of the data collectors have screens that support a horizontal orientation (similar to the notion of "landscape" when printing on standard paper), more compact data collection devices have been introduced with vertical screens ("portrait" in the paper printing analogy). These devices usually have a limited number of hardware keys and are intended to be primarily operated using the touchscreen. For example, the TDS Recon and the Juniper Systems Archer are widely used as platforms by third-party software manufacturers.
The flexibility of configurations for operating and screen layout help customers tailor their purchases to their work. "Devices with a vertical screen format are usually more affordable and weigh less than devices with keyboards, [and] weight is an important consideration for some customers," says Eric Hall, marketing product manager for survey at TDS. "On the other hand, the horizontal screen devices offer the ultimate in flexibility with full keyboards. And since they are bigger, we can include everything but the kitchen sink, and buyers with performance in mind tend to go for that."
ConnectivityNew developments in communication technology have inevitably flowed to the portable devices. One of these technologies is Bluetooth, an industrial specification for wireless personal area networks (PANs), also known as IEEE 802.15.1. Bluetooth provides a way to connect and exchange information between devices like personal digital assistants (PDAs), mobile phones, laptops, PCs, and in the case of surveying data collection, the data collector and GPS receiver, total station and other surveying instrumentation. Another is WiFi, which is the use of wireless local area networks (WLAN) based on the IEEE 802.11 specifications. In addition to these, other communication technologies have been developed to facilitate communication between the data collector and the total station and the GPS receiver, including spread spectrum 900 MHz, 2.4 MHz, UHF, VHF, and cell phone technologies such as GPRS and GSM. Data collectors usually have Bluetooth and WiFi capability built-in (sometimes available as options). The add-in technologies may be plug-in cards, add-on hardware that is permanently or semi-permanently attached, or external to the data collector.
Connections between data collectors and surveying technology can be made through two principal ways: serial ports (whether RS232C or USB) or Bluetooth. In the office, it is still common to use serial cables (though they may be integrated into some type of charging/data interface cradle or dock). Other methods of data transfer include WiFi and removable memory media (which necessitates a device attached to the computer that can accept that media).
MemoryMemory for software and data has expanded in capacity and reduced in physical size with each generation of data collector technology. While much of it is built-in, removable data modules are still available to support greater flexibility for the manufacturer, distributor and user.
Flexibility Now and in the FutureFlexibility has been a hallmark of the design of the modern data collector hardware. Slots for Personal Computer Memory Card International Association (PCMCIA) cards, Secure Digital (SD) cards and Compact Flash (CF) cards have abounded. These cards can be used for data or software or both. Some slots can be used for purposes other than memory, further increasing the ways in which data collection hardware can be applied to solve surveying problems. Functionality can be added by plugging the following devices into card slots: GPS receivers, cell phone modules, spread spectrum radios, USB ports, Bluetooth radio modules, cameras and 802.11 (WiFi) devices to connect to WLANs. More devices are likely in the future.
With such flexibility in options, customers are able to distinguish between different styles of hardware to best meet their data collection needs.
As technology continues to advance, the digital level, RTK and static GPS and laser scanner are now beginning to exert influence on the molding of data collectors. Other new surveying and mapping technologies will inevitably alter data collection hardware in the future, and this dynamic progress will continue to work in the surveyor's favor.