Using Empirical Map Projections for Modeling Early Nautical Charts
A numerical model using the concept of multidimensional scaling, generalized to distances and directions measured on the surface of the Earth, is presented and tested, with the objective of simulating the main geometric features of early nautical charts. Starting with a sample of points defined by their latitudes and longitudes, the process consists in rearranging their positions in a plane so that the differences between the initial (spherical) and final (planar) distances and directions between them are minimized. The geometry of the Cantino planisphere (1502) is simulated and the output is compared with the geographic grid implicit to the original chart, with satisfactory results. The model proved to be an effective and easy-to-use research tool and may be used, not only for simulating and assessing the various factors affecting the geometry of early nautical charts, but also for educational purposes e.g. illustrating the properties of map projections.
KeywordsIndian Ocean Magnetic Declination Angular Distortion Show Line Great Circle Distance
Unable to display preview. Download preview PDF.
- Cortesão A, Albuquerque L (1968) Obras completas de D. João de Castro, 4 vols. Academia Internacional de Cultura Portuguesa, CoimbraGoogle Scholar
- Gaspar JA (2008) Dead reckoning and magnetic declination: unveiling the mystery of portolan charts’. e- Perimetron, Vol. 3, No. 4: 191-203Google Scholar
- Gaspar JA (2010) From the Portolan Chart of the Mediterranean to the Latitude Chart of the Atlantic: Cartometric Analysis and Modeling. Doctoral dissertation, Universidade Nova de LisboaGoogle Scholar
- Jenny B (2006) MapAnalyst: a digital tool for the analysis of the planimetric accuracy of historical maps’. e-Perimetron, Vol. 1, No. 3: 239-245Google Scholar
- Jenny B, Weber A, Hurni L (2007) Visualizing the Planimetric Accuracy of Historical Maps with MapAnalyst’. Cartographica, Vol. 42, No. 1: 89-94Google Scholar
- Korte M, Constable, C (2005) Continuous geomagnetic field models for the past 7 millennia: 2. CALS7K. Geochemistry, Geophysics, Geosystems, Volume 6, Number 1. AGU and the Geochemical SocietyGoogle Scholar
- Nunes Pedro (2002) – Obras, Vol. I: Tratado da Sphera; Astronomici Introductorii de Spaere Epitome. Fundação Calouste Gulbenkian, Lisboa [1st edition: Lisboa, 1537]Google Scholar
- Tobler W (1977) Numerical Approaches to Map projections. In Kretschmer E. (ed.) Studies in Theoretical Cartography, p. 51-64. Deuticke, VienaGoogle Scholar