Hyperion in Faynan
Here’s another thing that came out while I was in the field, and that I meant to write something about. A paper by Stephen H. Savage, Thomas E. Levy and myself, titled “Prospects and Problems in the Use of Hyperspectral Imagery for Archaeological Remote Sensing: A Case Study from the Faynan Copper Mining District, Jordan,” was published in the Journal of Archaeological Science. Actually, it’s in the Feb. 2012 issue, but through the magic of the publishing process and the internet, this issue is already available. You can get the article from ScienceDirect here, and Steve has made the preprint available on his web site here.
As the title implies, one of the things we tried to do in this paper was describe the things that didn’t really work, as well as those that did. The inclusion of the section on the Principal Component Analysis is a good example. Some large-scale landscape features were clear, but the false positives and negatives were a bit troubling, and reflect some of the weaknesses of the method and the instrument itself. One of the biggest problems with using Hyperion for archaeological research is the rather coarse spatial resolution. Although the spectral resolution is quite good, with 242 narrow bands (for our purposes only 156 were usable), the spatial resolution is only 30 meters. As a comparison, newer commercial satellites like GeoEye-1 offer resolutions under 2 meters in multispectral bands, and under half a meter panchromatic. What this means is that some things just don’t show up on Hyperion images. For example, the primary focus of my research, Khirbat Nuqayb al-Asaymir, is a fairly large site (something like 7 hectares — 70,000 sq.m.), but it’s sparse enough that it’s basically invisible on the Hyperion images. This is something of a limitation, and one of the reasons that the focus of this paper is the Iron Age smelting center of Khirbat en-Nahas, which, as you can see if you read the paper, is pretty densely packed with slag mounds.
Anyway, I think it’s important to publish negative results along with the positive ones, and I’m glad that we did that here. You can, of course, read the paper and judge for yourself.
2012 Savage, Stephen H., Thomas E. Levy, and Ian W. Jones Prospects and problems in the use of hyperspectral imagery for archaeological remote sensing: a case study from the Faynan copper mining district, Jordan. Journal of Archaeological Science 39(2):407-420.