Documentation on Linking Data

With the first GIS map of Pompeii now available online, we are turning more of our attention to the problem of connecting our spatial data to our bibliographic data. While there is still some important spatial work to be done with the current map, the planning and documentation for the bibliographic integration serves as a worthwhile distraction. To that end and following a discussion last week with Alexander Stepanov, the PBMP’s GIS architect, I’ve decided to write up some very quick documentation for our data and their connections as a blog post. I’ve also decided to try something else new. Below is a Google Slide with the designs and discussions we drew on a whiteboard as the background. Over this are shapes representing files we need to link together with their names hyperlinked to their locations on the web (as hosted sites or Dropbox objects). In this way, the blog post operates in three different dimensions:

  1. As a public discussion
  2. As a living, internal document
  3. As an interface to the repository of files we’re using.

The files listed are as follows:

A single file of spatial data to start, the Propeties by Eschebach (Prop_ESCH), representing all the building and occupied spaces in the city. Later this will expand to include other, more generalized features of the landscape, such as the City Blocks, Gates, and Fortification Walls.

Three files from the Nova Bibliotheca Pompeiana are given here:

  1. The first 10,000 citations (GYG Citations_BIBLIOGRAPHY) completed from the NBP as there were prepared for uploading to Zotero (and then to Omeka). This shows how the data were divided and might be recombined.
  2. A list of property addresses from the Spatial Index from the NBP (GYG Citations_INDEX). This gives as a one-to-many relationship the address of a property and the one or more citations that relate to it.
  3. A list of addresses per citation as extracted from the full-text of the first two volumes of the NBP (GYG Citations_TEXT). This gives as a one-to-many relationship the bibliographic citation as given by Garcia y Garcia and the one or more addresses that relate to it.

Naturally, there will be a significant overlap between #2 and #3, which will reduce the total number of connections, but also offer a chance to preform quality control test on the data as extracted from the NBP.

If thinking of this a merely a spatial data problem, the work to be done is non-trivial, but also not conceptually difficult. That is, if all we wanted to do was to connect the bibliographic data to the map so that users could click on it and access that information, the process would be straight-forward: combine and proof tables #2 and #3, then join them to the spatial data of Properties by Eschebach. Indeed, that *is* our primary goal, but we also want those bibliographic citations to be linked to their full references on our other platforms (i.e., Zotero and Omeka). Moreover, we want users to be able to use search functions in the map – beyond navigating and clicking – to both find and leverage bibliographic information. For example, we want people to be able to search for an author in the map and have the sites and buildings associated with that author appear highlighted. The user should also then be able to create a new search off of this subset of data, using either additional bibliographic criteria or spatial definitions. To make these functions possible, however, the data stored in the map cannot only be reference numbers linked out to other resources. Finally, we would like to eventually have searches in our bibliography be (passed to and) responsive in the map, so that the results of regular bibliographic searches might be visualized in the map as well as in the listing of citations.

As you can see from teh image, we’ve got an outline of how we’ll do this. Nonetheless, if you are a GIS architect, a digital collections librarian, data designer, or all around smart person and have an opinion on how this might be done, in all or in parts, please do email me: Pompeiana[AT]gmail.com

– EP

Pompeii: The First Navigation Map

The PBMP’s first full map for navigation is now online. You can start to explore Pompeii in the map embedded below, or go to the full site for more space and options. If you want to customize the map or make a presentation from it, sign in to / sign up for your ArcGIS Online account and save a copy to your own webspace. The link is at the upper right of the embedded map page. [Click here to download the files as a map package or as Shapefiles (with minor improvements from online version) or as an illustrator file of just the architecture]. Below the map is additional information about the files, the information they contain, and their display.

The “Pompeii: Navigation Map” is essentially a set of nested tiles that change the display of the city as one zooms in and out to change the scale of the map. Overlying these are a series of vector-based files, which are used almost exclusively as invisible, data rich layers. That is, the transparency for many of the files set to 100% so that the information about Pompeii those files hold can be accessed (via a pop-up window), but their rendering does not slow the loading of the map.

Users may find the information in the following files to be of interest:

Data-Rich Layers

Elevations Points: This layer is turned off by default and set to not appear until the view scale reached 1:2500. Above sea level elevation data at 5cm or 10cm resolution from multiple sources: Corpus Topographicum Pompeianaum (1984); De Caro, S. (1979); Eschebach and Müller-Trollius (1993); Etani et al, 2003; Pompeii Archaeological Research Project: Porta Stabia.

Eschebach ALL: (West & East). Due to the number of features in the original file (Properties by Eschebach), the file was split in two along the via Stabiana. The user should notice little difference. There are, however, some significant issues to be aware of in the spatial consistency of properties for those interested in the area of individual features. Because the properties were drawn to express the functional categories assigned by Eschebach and not the contiguous physical boundaries of the building, there are overlaps, gaps, and duplications in the data. We are working to improve these data. For the moment, caveat emptor. These files do, however, contain information of importance to researchers, including:

  1. Address of the Primary Door according to Eschebach (1970; 1993).
  2. Functional Category according to Eschebach (1970; 1993).
  3. A link to image of the property at Pompeii in Pictures.
  4. The Date(s) of excavation according to the Corpus Topographicum Pompeianaum (1984).
  5. Area of the property in square meters.

PBMP CTP (Features): The 628 properties in this file represent the properties described in the “Structures” section of the Corpus Topographicum Pompeianaum (1983), pars. II. This layer contains information of importance to researchers, including:

  1. Address of the Primary Door.
  2. Page number of the information in the Corpus Topographicum Pompeianaum (1983), pars. II.
  3. All known names of the property: Name (1) – Name (15).
  4. Bibliographic reference for each known name of the property: Ref. Name (1) – Ref. Name (15).
  5. A link to image of the property at Pompeii in Pictures
  6. Area of the property in square meters.

Display Layers

Fortification Walls: Sixteen sections, between the defensive towers and city gates, of Pompeii’s extant fortifications are shown and named.

Defensive Towers: Eleven of the twelve known (by inscription) defensive towers surrounding Pompeii are shown and named.

Gates: The seven known gates to Pompeii are shown and named.

Unexcavated Areas: Three primary areas still not yet excavated (in Regions I, III, IV, V, and IX) are shown and named, as well as isolated areas along the interior of the fortification walls.

City Blocks: The excavated extent of the city blocks (insulae) are shown and labeled.

Streets: There are 97 streets and passage areas represented in this file with the extend of the street and its name given according to their modern conventional nomenclature (in Italian).

Alleys: Six passages within city blocks and disconnected from the street network shown and named.

Sidewalks: The excavated extent of the pedestrian sidewalks are shown.

Stepping-Stones: The 316 known stepping-stones within the street network are shown and named.

Forum: The forum, though also given a designation as a city block (VII 8), is shown here as its own feature.

Water Towers: The twelve water towers are located and labeled according to the nomenclature established in Larsen, 1982.

Fountains: Thirty-four public fountains, including both the complete footprint of the fountain and its interior basin, shown, symbolized to show the basin with water, and named.

Projected City Blocks (insulae): This is layer is turned off by default and expresses 46 extrapolated city blocks that remain partially or completely unexcavated. Some areas are almost certainly accurate (Regions I, III, and IX), while other are somewhat more speculative (Regions IV and V).

PBMP CTP (Tiles): This layer is turned off by default and represents the location of the 628 properties described in the “Structures” section of the Corpus Topographicum Pompeianaum (1983), pars. II. This layer visualizes the locations in the PBMP CTP (Features) layer, but does not contain that layer’s attribute data.