Zprávy památkové péče 2018, 78(1):54-58 | DOI: 10.56112/zpp.2018.1.09

Processing aerial photographs and publishing them in the Archeological Map of the Czech Republic information system

Martin Gojda¹, Lucie Čulíková²

¹ Filozofická fakulta ZČU v Plzni

² ZČU v Plzni

One of the most important results of survey activities of the aerial archaeological program, both in general and specifically in the case of the Archaeological Institute of the Academy of Sciences in Prague, is the acquisition, primary processing and storage of a large number of oblique aerial photographs (Aerial Photograph Archive - ALS - containing approximately 23 thousand digital photos and negatives and slides converted into electronic format). To utilize the potential of this fund would mean processing them further, i.e. transforming interpreted images of buried archaeological sites that capture prehistoric and historic settlements through (predominantly) vegetation symptoms into plans. This means rectifying oblique images in GIS/ArcMap using orthorectified and georeferenced (vertical) aerial photographs (orthophotography) and subsequently digitizing (or vectorizing) their archaeological content into a separate layer. In this way, ready plans of aerially photographed sites are gradually prepared as shapefiles which can be later viewed on the background of satellite or aerial imagery, orthophotomaps, or topographic maps available through internet geoportals (e.g. Cenia, ČUZK).
From the point of view of accessibility, the aerial photo data in the AMCR information system is placed into two of four groups (A-D). The decision to include them into one or the other is based on the need to protect archaeological sites recorded by aerial surveys. The purpose of this categorization is to allow access to aerial photographs to interested parties from the general public while at the same time maintaining restraint in permitting access to images of such locations whose character (especially burial, ritual, and other sites potentially rich in finds of movable - especially metallic - artifacts) would predetermine them to danger should their location be made public. The decision on the scope of accessibility of aerial photographic data (images and their metadata) was based on the principle of openness which is generally the backbone of the access policy to AMCR data.
The aerial photographs are therefore located in AMCR as follows:
1. in Group A - images to which all interested parties (both professional and the general public) have full access. These include a) photos of most of the sites identified by vegetation, soil, etc., through a visual aerial survey, b) photographs of physically preserved (on the land surface) archaeological and building-historical monuments and urban (or other artificial/man-made) building and landscape features, c) photographs of natural structures/phenomena (e.g. extinct river beds) usually related to the documented settlements of past populations, and finally d) aerial photographic documentation of large-scale archaeological excavations.
2. in group C - on-line access to aerial photographs and their metadata is given to only the professional (academic) community, more precisely the employees of authorized archaeological organizations (AAOs) who are authorized to further the agenda on behalf of the AMCR and are named in the agreements between the Archaeological Institutes of the ASCR and AAOs. These are photos of sites whose former features indicate a high probability of the presence of an increased number of artifacts made from precious/colored and ferrous metals (especially modern militaria). As indicated above, the inclusion of archaeological sites in this group is primarily intended to help protect them from the illicit activities of prospectors who most often use metal detectors to identify movable components of archaeological heritage.

Keywords: aerial photographic data, aerial photograph archive, archaeological heritage, advanced data processing, online data availability

Published: March 1, 2018  Show citation