Surface Interpolation

Above are several examples of ways in which surface data can be visualized to see patterns in settlement in a region.  In this case, points connected to data on artifact numbers and population estimates were used to show where communities were located in the past.  By looking at these patterns, one can infer the level of local and inter-community communication in past societies.  

Oaxaca Survey Grids - Georeferencing and Digitizing

  






































Paper maps and documents are often the primary sources of historical data and site reports.  This week we focused on how to take this type of data and incorporate it into ArcMap documents.  Being able to view and examine landscape data in this way is an important new method for analysis and interpretation in settlement pattern studies.

Maps and site data from a published report of a survey done in Oaxaca, Mexico were available as scanned files in .pdg format.  The maps were made into jpegs and then georeferenced to a topographic basemap.  Then they were digitized: grid squares, soil maps, and site plan maps.  By combining these map layers, archaeologists can make inferences about settlement patterns and how these relate to environmental conditions.

The last step involved joining data in an Excel spreadsheet from the site report with the newly created shapefiles showing the sites in each grid.  In this case, the resulting data shows the low population figures for the period IIIB sites in grid N9E8,

Looking at this map, it is difficult to make a guess about whether or not population size was a function of land type, since only 3 sites are involved.

Georectifying James Cook's 1785 Map of Macao

Historical maps can be fantastic sources of information, but they are rarely accurate enough to layer over current images without going through the process of georeferencing and rectifying.  This map shows a georectified map of Macao in 1785 layered over a recent image.

To do this, there must be at least 2 layers, and control points are added between the historic map and the modern one, using points that can be identified on both maps.  In this lab, we also added a topographic map to better identify specific locations.  As more points are added, the historic map shifts in location so that the 2 maps line up as much as possible.  In this case, 10 points were added before the map was rectified using a type of sampling called Cubic Convolution, which is used for data like images and photographs.

The purpose here is to highlight the changes in landscape and environment over time.  Other data can be examined using this method, such as population trends and settlement patterns. It can be used at a variety of scales, from neighborhoods and cities, to larger regions.