Sun 29 Jul 2007
Broad-based web GIS for archaeology
Posted by under Agency , Contractor , cultural resource management , cyberinfrastructure , GIS , open access , open data , policy , projects , reports[4] Comments
        Fennelle makes a good point. My impression is that agencies are often protective of their GIS data and may fear that wide disclosure will lead to people with nefarious purposes knowing where sites are located. One of the frustrations (also an opportunity) is that through CRM investigations incredibly detailed GPS and GIS databases are often built-up about archaeological sites or regions, but there is no policy in place or architecture for capturing much of that data long-term. For example, my firm often conducts GPS-based archaeological survey such that every artifact collected is associated with a GPS point (for example in a controlled surface collection). But typically, agencies will only want one or a few GPS points for each site (or a shapefile with site boundaries). A lot of these points are also, or could be tagged with information on stratigraphy, soils, slopes, groundcover, or prior distubance. So aside from legacy data storage within your own firms’ archives there is no long-term organized effort to preserve the painstakingly collected data. I am sure there are people in SHPO offices and elsewhere who would be interested in a broader-based archaeology GIS (currently state CR GISs work well but data collection/display is somewhat limited).                                               Â
         The possibility is that web-based and accessible formats could be used to store and make available archaeological data without compromising the need to secure certain kinds of data. A collaborator of mine has written an XML data format that could be used to tag archaeological data in ways that could be read by various internet scripts. It is pretty basic right now but it or something like it could make distributed GIS or GPS archaeology on the web more possible! He and I also are collaborating on a webviewer that allows for analysis of spatial archaeological data within any webbrowser (he is the programmer not me!).  Both icon and color-based intuitive analyses (Jacques Bertin’s visual variables) as well as results of quantitative analyses are available. I’ll post some more information on these ideas if anyone is interested in seeing it.
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Kevin Schwarz
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August 3rd, 2007 at 3:10 pm
One thing not discussed with regard to this GPS data accuracy is the issue of scale and appropriateness. What I have found is that state and federal agencies are beginning to become sensitive to the need to have accurate data, but they often really have very little understanding of what data accuracy entails. The assumption is made that better technology should be used if it is available, and the cost of using it is often placed upon the developer or agency undertaking the project. However, sub-meter accuracy in recording site locations (or site boundaries) is ridiculous for a Phase I Survey. When you consider that all archaeological sites are, in essence, point-clouds, and that shovel testing is a sampling process, how do you define their boundaries? What does a boundary even mean given that significant sites are also defined by activity areas (some of which may have no remnant artifacts at all), human-altered landscapes, Traditional Cultural Properties, and the like? The concept of “site” has been seriously questioned for decades, yet we may be mandating sub-meter accuracy in recording vague undefined boundaries? This strikes me as completely inappropriate.
All Cultural Resource Management is exactly that: “management” of the resources. This means that collection of data should be at the appropriate scale to complete the management tasks for the undertaking. In other words, for a Phase I survey, the management tasks are to identify the general nature and location of the site(s). Sub-meter accuracy GPS points are not necessary, and one should expect boundaries to change for NRHP-eligible resources during the Phase II and Phase III processes (because they always do). The management task for a Phase II is to identify the level and area of “significance” for the site – not to interpret that significance, or address research questions. In that case, the level of accuracy needed is merely enough to ensure that no significant portions of the site will be adversely effected by the undertaking (and that might require sub-meter accuracy, but usually doesn’t). It is at the Phase III level that sub-meter accuracy IS required, but why bother with a GPS, when it can be done much more accurately with a total station? Several sub-meter accurate GPS points may be required to triangulate a total station datum point, but beyond that the total station will be much more accurate (mms rather than 10s of cms).
Ultimately, the point is that data standards and expectations need to fit the scale of management and investigation. Better technology does not mandate its use in all situations. Just because we can tag additional information to GPS points does not mean that it should become required.
We need the people who are making data quality decisions to be aware of these issues (which are much the same in academia as well) and act on them appropriately. To date, I am seeing little awareness of them. All of this is irrespective of the nature of data storage, transfer, and sharing.
- Tom Whitley
August 8th, 2007 at 12:29 pm
The advent of GIS- and GPS-based archaeology in CRM is as much driven by our clients’ needs as our own needs for data accuracy. Although Tom makes a good point, all that you really need to locate a site on a Phase I survey (often) is a topographic map and a ruler, agencies and private clients usually have Arcview or AutoCadd maps/databases for their projects and expect us to be able to place your survey finds in the project context they have created.
So I do not think it is generally ridiculous to GPS our sites/finds at the Phase I level. In addition to relocating sites/finds this information is often used to help clients’ projects avoid specific sites (or portions of sites) or better understand potential impacts. There are some cases where GPS data (or intensively collected GPS data at least) is not needed, but I can think of several large-scale CRM projects in the Midwest that have developed extensive GIS databases partly for archaeology that utilize GPS units intensively to integrate field-collected archaeological data with other project information.
The point my original post though is that CRM or other archaeological data is often collected digitally and full advantage should be taken of the capabilities of digital technology. I believe that the DDIG discussion is about archiving or using the web to make data accessible, foster collaboration, and share information for archaeological purposes, which include but are not limited to cultural resource management. Phase I archaeological databases have value from the perspective of settlement pattern and landscape archaeology, irregardless of whether Phase II and Phase III investigations are performed at particular sites. Another example, the Traditional Cultural Places (TCP) concept that Tom refers to is not always conducive to GPS-based surveys however researchers have used GPS and GIS to inventory traditional places (e.g., rock art sites) in collaboration with indigenous groups as a means of legitimating traditional cultural sites and territories.
Kevin Schwarz
September 21st, 2007 at 2:48 pm
My comment wasn’t that use of GPS on the Phase I level was ridiculous, it was that “sub-meter accuracy” GPS was ridiculous. There is a world of difference with respect to cost (though it is not as much as it was in the old days of selective availability). My point was that “taking full advantage” of digital technology does not mean disregard of the appropriateness of the scale and its applicability to the resource and the project.
I fully agree that GPS is a useful tool in Phase I survey, and I have been using it in Phase I surveys since at least the early 1990s. But, as we are all aware, a little knowledge in the wrong hands is a dangerous thing. Let’s not become enamored of technology to the point where the cost of collecting the data outweighs its usefulness.
Tom Whitley
October 4th, 2007 at 10:15 pm
Right, I understand what you mean. Our Trimble handheld unit has a software slider that opposes “precision” with “productivity”. If you choose precision (depending on satellite geometry and other factors) you may be able to achieve submeter accuracy. However, the cost is the amount of time it takes to receive a set of coordinates with the GPS unit. If you choose productivity, you get quick read-outs but you’re sacrificing accuracy. Choosing productivity might be an appropriate choice,depending on the Phase I survey goals and requirements.