Archaeology 101: GIS
This year my Campus Archaeology Program project is going to be incorporating information from recent Field School’s into the pre-existing GIS map made of the Campus. This will include mapping Shovel Test Pit and excavation location and detail information. The ultimate goal of this project is to integrate all the previously gathered data obtained during CAP excavations and Field Schools to determine the predictability of finding artifacts at specific locations on campus.
GIS stands for Geographic Information System and works as a means of storing, analyzing, and displaying digitized data in a spatially meaningful way. This means that a wide variety of data can be mapped spatially including cartographic information and statistical information. This allows maps to be developed not only in a two dimensional way with street and building information, but also three dimensionally with elevation and topographic information. Statistics can also be incorporated into this as well, for example, allowing mapping of different demographics.
Data is put into digital form through two main types of data storage, raster and vectors. A raster is a pixel. The data is stored is rows and columns of cells. Each cell, or pixel, is assigned a value that could be anything from elevation, temperature, land use, etc. All these pixels come together to form a larger image. The value of storing data in raster cells is that is allows data to be displayed continuously, for example, elevation models are best displayed as a raster model because it allows for discreet continuous changes in elevation to be shown.
Vectors are a way of displaying data in three different types. Points, which allow for representation objects that require only a single point reference. Another data illustration that vectors allow for are lines, which allow for information such as roads, rivers, and topographic lines to be displayed one-dimensionally. The final type of data display is polygons, which allow for two-dimensional image depiction. Vector is usually seen in more in illustrating roads, lakes, sites, and other information in polygons.
When we use GIS at Campus Archaeology, we use both raster and vector layers. For aerial photos or elevation models we use vector data because it creates pictures. For information about the campus itself and our sites we create vector data. By combining the two we can create a model of campus that we can analyze.