3. Direct vs indirect survey techniques
As a last issue, I want to address the undeniable tension between the goals of the Cultural Heritage field and the aims and strategies of the geomatics industry from which it borrows tools and practises. This tension comes from the inherent nature of these new optical sensing techniques and how it alters the cognitive aspect that is related to the survey of heritage. In the past, surveying was often defined as a practise in which: “The first objective of a survey should be to record what is necessary in order to understand and to illustrate the history of the building” (ICOMOS, 1990). A definition that was later paraphrased in the ICOMOS Sophia Principles for the recording of monuments, groups of buildings and sites (1996), and in the RecorDIM publications of the Getty Conservation Institute (Letellier, Schmid and Leblanc 2007). All these publications recognise that surveying is a cognitive process enabling the understanding of heritage. Adopting new techniques from the geomatics community has altered the aspect of “understanding”, because it changed the momentum of data selection [De Vos 2022, in press].
To explain this, first we need to look at the distinction between “direct” and “indirect” survey techniques. Under the name direct techniques we can group tools such as a Total Station (TS), hand-measured drawing, global navigation satellite systems (GNSS), etc. because interpretation and selection are actively made at the point of capture. They provide differentiated datasets relying on the surveyor understanding the extent and depiction of the subject to be mapped at the time of survey (Blake et al. s.d.). Indirect techniques, such as photogrammetry and 3D laser scanning are characterized by recording large amounts of undifferentiated data at the point of capture. Further processing and selection from that data, is done off-site (Blake et al. s.d.).
This distinction is an important one to make because it clearly explains the selection mechanism behind both techniques. However, when misinterpreted, it seems that when and where this selection finally is made is without consequence. In a recently published article the director of preservation studies at the Texas University, Brent Fortenberry, writes: “While the investigative component remains constant, digital technology moves the moment of documentation translation from the point of contact with the building into a third space—the studio or lab” (2019). This is not the case. Like I have argued above, the investigative component does not remain constant, because in most cases we are only investigating approximations of the surfaces – and not the objects itself.
Looking into the tradition of the German school of Building Archaeology, we see that surveying through close observation (in contrast to remote optical sensing) is much more than just a means of recording information, it is regarded as a research method as such (Busen et al. 2017). In fact their precursor Manfred Schuller is extremely critical towards the use of indirect measuring techniques to be applied for the metric survey of built heritage. He states that “the fundamental problem is that the analysis is separated from the object, so that one of the basic rules of building archaeology is not fulfilled” (2002). He warns that “this violation will take its revenge!”(ibid, 15). With the basic rule, he refers to his belief that “measuring and drawing must always take place on site in a combined process [as] only this approach sharpens the eye for critical observations and forces the mind to go to work.” (ibid, 11).
Personally, I plead for a holistic approach that combines the benefits of optical sensing techniques, with those of close observation and hand measurements (De Vos 2017). Although this seems all to obvious, in practise the use of combined methods are not a commonplace. We have reached a point in which we are travelling at two speeds. While not so long ago, surveying and research (understanding) was more or less interrelated, and thus taking place at the same speed, we now need to remind ourselves that although technology has offered a quick alternative – a price-affective and highly automated recording – the understanding of heritage and the creation of a comprehensive (historical) narrative does not come overnight. The two processes are detached and travel at a different speed. Although seductive we should be aware not to succumb to a prioritisation of digital 3D data acquisition over added heritage knowledge results. The use of technology should lead not so much to faster research but to better research.
Blake, B., Lunnon, S., Bedford, J., Andrews, D., Becket, N., Thomason, B., s.d. Metric Survey for Heritage Documentation, Documentation for Conservation, A manual for teaching Metric Survey Skills, English Heritage, Getty Conservation Institute [unpublished]. [online: http://bill-blake.co.uk/files/Download/CIPA%20Recordim%20Teaching%20Guide.pdf]
Busen, T., Knechtel, M., Knobling, C., Nagel, E., Schuller, M., Todt, B., 2017. Bauaufnahme, Munchen.
De Vos, P.J. 2017. “Documenting for Posterity: Advocating the Use of Advanced Recording Techniques for Documentation in the Field of Building Archaeology”. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences, IV-2/W2, 59–65.
De Vos, P.J., 2022. “Reflection on the use of a Total Station and Hand-Measured Drawing for the Metric Survey of Built Heritage”; in:, B. Blake, M. Santana & A. Vandezande (ed.), 20 Years of Archdoc at the Raymond Lemaire International Centre for Conservation, Leiden [in press].
Fortenberry, B., 2019. “Digital Documentation in Historic Preservation Education and Research: Prospects and Perils”, Preservation Education & Research, 11, 81-116.
International Council on Monuments and Sites, 1996. Principles for the recording of monuments, groups of buildings and sites. Sofia. [online: https://www.icomos.org/en/charters-and-texts/179-articles-en-francais/ressources/charters-and-standards/387-principles-for-the-recording-of-monuments-groups-of-buildings-and-sites-1996]
International Council on Monuments and Sites, 1990. Metric Survey Guide to recording historic buildings, London.
Letellier, R., Schmid, W., & Leblanc, F., 2007. Recording, Documentation, and Information Management for the Conservation of Heritage Places: Guiding Principles. Los Angeles.
Rączkowski, Włodzimierz. 2020. “Power and/or Penury of Visualizations: Some Thoughts on Remote Sensing Data and Products in Archaeology”, Remote Sensing 12 (18): 2996.
Schuller, M., 2002. Building Archaeology, ICOMOS VII, Lipp GmbH, München.
The London charter for the computer-based visualisation of cultural heritage, 2009. [online: https://www.londoncharter.org/fileadmin/templates/main/docs/london_charter_2_1_en.pdf]
Tylman, W., 2018. “Computer Science and Philosophy: Did Plato Foresee Object-Oriented Programming?” Found. Sci., 23, 59–172.
Verhoeven, G., 2019a. “The 3D datafication of cultural heritage: more than just a flash in the pan?”, keynote presentation, at: The 27th CIPA Heritage Documentation international symposium “Documenting the past for a better future”, Avila.
Verhoeven, G., 2019b. “Resolving some spatial resolution issues – Part 2: When diffraction takes over”, AARGNEWS, 59, 12–23.