﻿ Cartography

Methods of cartography

All the maps are equidistant cylindrical projections.

Our JAVA applets use the formulas of the equidistant conic projection (which dates back to Claudius Ptolemy) with standard parallels which are equidistant from the Equator.

Standard parallels : 13.467° N (Phnom Bok) and 13.467° S

The formulas are provided by http://mathworld.wolfram.com/ConicEquidistantProjection.html

The straight lines are loxodromes ie lines of constant bearing. The circles are the loci of points located at a given number of meters from a centre. We took into account the World Geodetic System of 1984 (WGS84).

The latter is described by  http://home.online.no/~sigurdhu/WGS84_Eng.html .

Our goal was to reproduce the work of an ancient surveyor.

Each depicted temple was digitized in the following way.

An outline in which two features were identified was traced from a satellite image or from a plan of the “École française d’Extrême Orient” (EFEO). The cartesian coordinates of the pixel elements of the outline were determined by a computer program “EditJpeg.exe” (Durham, 2002) and the pairs of coordinates stored in a file. With the help of the cartesian and geographical coordinates of the two features, the JAVA program calculates the geographical coordinates of each pixel and depicts them on the cylindrical projection.

Copyright Robert Bywater & Jean-Pierre Lacroix

rab1@ancientcartography.net