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Jenny, B. and L. Hurni (2011). "Studying
cartographic heritage: Analysis and visualization of geometric
distortions." Computers & Graphics 35(2): 402-411. Old maps are increasingly used as a source for historical research. This is a consequence of the increased availability of old maps in digital form, of the emergence of user-friendly Geographical Information Systems, and of a heightened awareness of the unique information stored in old maps. As with every source for historical studies, when old maps are georeferenced and information is extracted for historical research, the accuracy and reliability of the geometric and semantic information must be assessed. In this paper, a method based on a series of geometric transformations is presented, which transforms control points of a modern reference map to the coordinate system of an old map. Based on these transformed points, the planimetric and geodetic accuracy of the old map can be computationally analyzed and various visualizations of space deformation can be generated. The results are graphical representations of map distortion, such as distortion grids or displacement vectors, as well as statistical and geodetic measures describing the map geometry (e.g., map scale, rotation angle, and map projection). The visualizations help to assess the geometric accuracy of historical geographical information before using the data for geo-historical studies. The visualizations can also provide valuable information to the map historian about the history of a particular map and its creation. Laycock, S. D., P. G. Brown, et al. (2011). "Aligning archive maps and extracting footprints for analysis of historic urban environments." Computers & Graphics 35(2): 242-249. Archive cartography and archaeologist's sketches are invaluable resources when analysing a historic town or city. A virtual reconstruction of a city provides the user with the ability to navigate and explore an environment which no longer exists to obtain better insight into its design and purpose. However, the process of reconstructing the city from maps depicting features such as building footprints and roads can be labour intensive. In this paper we present techniques to aid in the semi-automatic extraction of building footprints from digital images of archive maps and sketches. Archive maps often exhibit problems in the form of inaccuracies and inconsistencies in scale which can lead to incorrect reconstructions. By aligning archive maps to accurate modern vector data one may reduce these problems. Furthermore, the efficiency of the footprint extraction methods may be improved by aligning either modern vector data or previously extracted footprints, since common elements can be identified between maps of differing time periods and only the difference between the two needs to be extracted. An evaluation of two alignment approaches is presented: using a linear affine transformation and a set of piecewise linear affine transformations. --
Dr. Duane F. Marble Email: dmarble at OregonFast.net
2226 Primrose Lane Telephone: 541.902.8837
Florence, OR 97439 Cell: 541.991.1730
Emeritus Professor of Geography -- The Ohio State University
Courtesy Professor of Geosciences -- Oregon State University
An early comment on the proper use of GIS technology:
"I warne yow wel, it is no childes play"
Originally from Chaucer, but also quoted by me in 1967 in a
monograph on software tools for computational geography
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