Digitizing the Upham Map
C. Identifying Data to Record from Upham's Map
Digitizing Upham's map involves several different steps:
-
Test digitizing: For demonstration and
experimentation purposes, immediately digitize the points of Upham's
map.
-
Establish control points:
Simultaneously research information about existing sites depicted on
Upham's map, so that the data created from this map could be matched to
other contemporary data about Salem and Essex County,
Massachusetts.
- Registration of the map: Use
control points to register, or fix, the real world location of Uphams
points, and assigning geographic coordinates to the image.
- Digitize georeferenced points: From
the registered image, digitize points and harvest geographic
coordinates.
- Adjust locations: Compare Upham's map
to known contemporary data and correct his locational data as
necessary.
- Build and link attribute database:
Link the geographic data to an attribute database about the participants
in the trials to create demographic mapping.
- Merge data from Upham with data created
from other sources: Georeferenced data will match with
data created from the Pereley/Freeman and Andover Historical Society
maps.
This process is slightly backward from what might usually be done: that is,
we might normally have first researched existing sites to obtain a series of
known "control points" that could be used to anchor the Upham map as we
digitized. However, we recognized that this would take time and effort, and
we felt that it would be useful to have a point coverage of Salem available
to experiment with, even if it were not "geographically aware," or
referenced to a real-world coordinate system.
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