Analysis of Geometric Distortion / Cartographic Heritage

MapAnalyst

We develop methods for analyzing the planimetric distortion and accuracy of old maps and map diagrams. Distortion grids and other specialized visualizations can be created with MapAnalyst.

MapAnalyst is a specialized software for the geometrical analysis of map diagrams and old maps. It can generate distortion grids, displacement vectors, and isolines of scale and rotation to illustrate local map deformation.

MapAnalyst was reviewed in the journal Cartographica and was judged "a great piece of software for analysing old maps, and one would expect MapAnalyst to be a welcome addition to the desktops of map researchers everywhere". MapAnalyst has been used by several map historians for the study of old maps.
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    Distortion grid and position differences for the London Underground map

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    Distortion grid for the London Underground map on a Mercator projection

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    Isolines of local scale for the London Underground map

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    Displacement vectors for the London Underground map


Jenny, B. (2010)
New features in MapAnalyst.
e-Perimetron, 5-3, p. 176–180.

Jenny, B. and Mesenburg, P. (2011)
MapAnalyst – Analyse und Visualisierung zur Genauigkeit der Mappa critica des Tobias Mayer (1750). Cartographica Helvetica, 43, p. 43–48 [German].

Jenny, B., Weber, A. and Hurni, L. (2007)
Visualizing the planimetric accuracy of historical maps with MapAnalyst.
Cartographica, 42-1, p. 89-94.

Jenny, B. (2006)
Geometric distortion of schematic network maps.
Bulletin of the Society of Cartographers SoC, 40, p. 15-18.

Geometric Analysis of Cartographic Heritage

Old maps are increasingly used as a source for historical research. As with every source, when old maps are georeferenced and information is extracted for historical studies, the accuracy and reliability of the geometric and semantic information must be assessed. We describe a method based on a series of geometric transformations that 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 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, map projection). The visualizations help 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.
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Orange is a copy of black, but not blue: The displacement vectors of the Hassler and Nötzli maps coincide, the vectors of the Atlas Suisse are spatially unrelated (credits to Dr. Martin Rickenbacher, Federal Office of Topography swisstopo)


Jenny, B. and Hurni, L. (2011)
Studying cartographic heritage: analysis and visualization of geometric distortions.
Computers & Graphics, 35-2, p. 402–411.

Jenny, B., Jenny, H. and Hurni, L. (2009). Alte Karten als historische Quelle - Wie lässt sich die geometrische Genauigkeit des Karteninhalts abschätzen? In: Karten, Kartographie und Geschichte - Von der Visualisierung der Macht zur Macht der Visualisierung / Cartes, cartographie et Histoire - De la visualisation du pouvoir au pouvoir de la visualisation, Koller, C. and Jucker-Kupper, P. (eds), Zürich: Chronos. p. 127-144.

Digitization of Historical Physical Terrain Models

Non-contact 3D digitizing techniques allow for the digital preservation of historical physical terrain models. By comparing the digitized terrain models with modern digital elevation data, the accuracy and distortion of historical terrain models can be analyzed. Non-contact 3D digitizing techniques not only provide a suitable data-capture method for solid terrain model analysis but are also a means of preserving digital facsimiles of such precious artifacts.
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Historical relief model at the Alpine Museum, Bern.