About georeferencing the MBM monasteries' data

T. Matthew Ciolek

Document created: 29 Sep 2012; Last updated: 02 Oct 2012

Corrections & addenda to this document were kindly provided by:

  • TBA

Georeferencing the data

This process involves investigations aimed at linking (Hill 2006, Wiki.GIS.com - The GIS Encyclopedia 2012b) the monastery in question to its exact spot in physical space. Georeferencing of historical data is a complex, painstaking and fact-hungry operation. It requires intensive parsing of information contained in relevant books and web sites. It is a search for all extant scraps of information, however minute, that may cast additional light on the appearance and physical whereabouts of the investigated establishment. All gathered intelligence is closely examined, compared and interrogated in the manner worthy of Hercule Poirot or George Smiley. Competing inferences are juxtaposed and weighted; settled conclusions are ready to be reconsidered in the light of fresh additional information. Our team's experience teaches that this exercise involves seven consecutive steps:

(i) Naming the place - development of a detailed list of all current and historic names (including all multilingual spelling permutations) of the monastery to be georeferenced.

(ii) Describing the physical attributes of the place - development of knowledge of the monastery's prominent physical characteristics (e.g. tall structure vs. squat; compact vs. sprawling one; walled vs. unbounded; one with steep vs. flat roofs; stone structure vs. brick structure, walls of some colour vs. walls of some other colour, a monastery with a prominent gate vs. one with no such a gate, zigzagging path to the place vs. ordinary/unremarkable path, and so forth).

(iii) Situating the place in the environment - development of knowledge of the monastery's immediate geographical context (e.g. 3 miles north-east of landmark L, next to crossroads, a day of walking on the way down from a mountain pass M, by a riverbank, overlooking a lake, on the hill's crest, on an N/S/E/W slope of the valley, on the outskirts of settlement S, etc.).

(iv) Locating the place on a map or aerial photograph - initially a general, then progressively more specific determination of the physical whereabouts of a monastery that goes by one of the standard and variant names that known to us, say P, Q, R, etc., and is also known to be situated in some characteristic manner relative to the terrain features X, Y, Z, etc. This stage matches named monasteries' known ecological context (see step iii above) with observed ecological characteristics of the mapped/photographed environment.

(v) Identification of the place - weighing the probabilities that the known structure (or its prominent part, such as the great hall, pagoda, stupa, the main gate etc.) with known physical characteristics (see step ii above) does in fact correspond to an object/feature that (a) has similar apparent physical attributes (as depicted in the aerial/satellite photographs), and - simultaneously - (b) is situated in a physical place confirmed through step (iii) above. In order to perform this task well a researcher needs to train himself in the art of forensic examination of aerial photographs and making informed interpretations of presence/absence of vegetation, undulations of terrain, distribution of solid shapes and faint shadows, as well as subtle traces and intimations of recent and/or long-discontinued traffic of people, animals and vehicles (Wilson 2000).

(vi) Measuring its lat/long coordinates - getting as detailed as possible a reading of the lat/long coordinates of the structure depicted on maps and photographs. Latitude and longitude measurements can be calculated by hand from extant paper maps. Better still, they can be obtained electronically via the "LatLng Tooltip" provided by Google Maps Labs page of the Google Maps system. Obtained readings need to be taken as closely as possible to the centre of a structure determined in step (v) above and expressed decimal degrees, a measurement system where latitudes South of the equator and longitudes West of the zero meridian have negative values. The more detailed the measurement, the better. A measurement with 3 decimal points has an approximate precision of plus/minus 55 meters (at the equator). Four decimal points result in precision of plus/minus 5.5 meters (Wikipedia 2012l).

(vii) Recording the georeferenced data - monastery's standard name and coordinates are encoded within an appropriate KML-formatted data file. […].

By the end of this seven-step operation, however, there remains the inevitable question of the data's accuracy - as opposed to the mere precision of one's measurements. Obviously, precision and accuracy are not synonymous with each other (Wiki.GIS.com - The GIS Encyclopedia 2012a). No matter how carefully we work, there is always a chance that some unnoticed clerical or analytical error might have crept into our georeferencing endeavours. All our georeferencing activity is, therefore, always an ongoing hypothesis making activity. For this reason, each of our MBM conclusions concerning the exact location of the named monastic complexes takes insurance. This is a number that indicates whether the actual placement of a monastery in the physical terrain is likely - in the light of the available information - to fall within 200 m, 2 km or 20 km of the point indicated by our coordinates […]. In August 2012 the MBM project has georeferenced 574 monasteries. The overall discrepancy between the MBM and the real-life lat/long coordinates was judged to be: no greater than 200 meters - 37% of cases, no greater than 2,000 meters - 42%, no greater than 20,000 meters - 22%.

References mentioned in the above passage:

  • Hill, Linda L. 2006. Georeferencing: The Geographic Associations of Information. Cambridge, Mass. and London, England; The MIT Press.
  • Wilson, D.R. (David Raoul). 2000. Air Photo Interpretation for Archaeologists. Stroud, Gloucestershire: Tempus Publishing Ltd.

SOURCE:
Section "4.4 Main MBM-related procedures on the Internet" in:

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