For example, consider the basic digital total station equipped with a data logger but without dGPS, a graphical interface, or reflectorless capability:
Information flow is reciprocal – we have to set the instrument up correctly over a fixed point and provide it with locational information and the height of the target in order to make the instrument operational. The instrument records horizontal distance and angle, but it is dependent on us to select the location of interest, aim appropriately at the target and trigger the reading. It is also dependent on the staff holder positioning the target correctly over the object of interest, and on both human team members correctly recording any changes in target height. The instrument reports the three-dimensional coordinates back to the user and the process repeats iteratively in the conduct of the survey.
Access is reliable in the sense that total stations are well-established pieces of equipment. The fact that they are battery-operated might make them seem less reliable, but the days of instruments losing their settings when the battery is changed have gone, and a pair of batteries will typically last a full day's surveying. Total stations are fairly resistant to rain and dirt since they derive from applications in the construction industry, for instance, but there are limits, as evidenced in the appearance of screen or scope condensation and grit in the adjustment or focusing screws, for example. They are also reasonably portable, although carriage over long distance and rough ground generally benefits from the acquisition of a special backpack to replace the standard box
A total station is quite durable in normal use, although it responds badly to mistreatment. Students, for example, have it drummed into them to carry the instrument always in its protective box, and not to move it while the tripod legs are still attached. A survey will typically take place over hours if not days, so the durability of the relationship is long, although since an instrument might also be set up beside an excavation trench and referred to periodically, the durability of the relationship may be repeated but not permanent.
Trust in a total station is generally high, although this is (or should be) reliant on regular calibration checks and servicing. Errors will more often be caused by incorrect use, and surveyors become accustomed to performing mental checks that the readings returned by the instrument 'make sense'.
The level of procedural transparency is dependent on experience and may take time to develop. What the instrument is actually doing beneath the surface is not transparent, especially to a novice. However, although training is required in the use of a total station, this experience can generally be applied to instruments from a range of manufacturers since the basic essentials are the same even if the location of buttons etc. differs. While an instrument can be used by rote, understanding of the principles behind the recording procedures is valuable in ensuring that errors do not occur, or are recognised and can be corrected. Furthermore, understanding of the range of tools provided by the software beyond the straightforward capture of three-dimensional coordinates can enhance the setup of site grids etc. but this requires a greater knowledge of surveying practice.
Informational transparency is not particularly high, since although the coordinates generated are easily understood, keeping track of where readings have been taken is down to the skill of the surveyors. In addition, evaluating the results will generally require the data to be downloaded onto a computer and some subsequent processing undertaken for visualisation purposes. Transparency is significantly enhanced if output onto a graphical screen is built into the instrument.
Scope for individualisation is limited. There are few customisation options available beyond adjusting one or two default settings so a total station can generally be used by anyone with the appropriate knowledge. The extent to which surveyor and instrument are entrenched is debatable: for instance, one might claim that the ability to contemplate large-scale close-interval three-dimensional surveys was made possible by the increased availability of total stations; on the other hand, the level of intervention by the instrument is less significant than the processing and visualisation software in this sense.
To a degree, the application of total stations has been transformative. Anyone with experience of capturing three-dimensional coordinates using tapes and a dumpy level will know the difference the introduction of a total station makes, for example. However, it again seems more likely that the visualisation tools used subsequently are more transformative than the data capture device itself.
Overall, therefore, a total station presents a mixed picture in terms of these cognitive dimensions. It ranks reasonably high in terms of access, durability and trust, and, after training, on procedural transparency. It scores low in terms of informational transparency and individualisation, and it is difficult to assess transformative capacity although this is also likely to be relatively low. However, the reciprocal information flow would indicate a relatively close integration between agent and artefact. Indeed, the instrument is entirely dependent on the human agents for its operation, supplying in return a faster and more efficient way of measuring distances, vertical and horizontal angles and calculating three-dimensional coordinates for selected locations. Pre-digital devices required the human surveyor to read and manually record the parameters and subsequently undertake the calculations, so in this respect the digital device complements (in the sense that the human agent could otherwise perform the measurements and calculations themselves) and extends (in that the measurements and calculations are performed faster and easier than using the manual method). Human intervention and negotiation is nevertheless required, although the level and content of communication between the two surveyors is less than required for a plane table survey, for instance, and is largely replaced with the introduction of reflectorless devices, robotic total stations, and ultimately laser scanners. As survey instrumentation becomes digital and increasingly automated, so the level of human engagement changes: the cognitive load is transferred to the digital device while the survey strategy and (for now) the physical assembly and setup of the instrumentation remains on the human side of the relationship. The complexity of the task is increasingly taken over by the cognitive artefact. Correspondingly, the remoteness of the human agent from the details of the process increases – for example, time spent discussing the specifics of individual features and ensuring their accurate representation within the data is reduced considerably as the cognitive load moves from the human to the digital agent.
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