Africa, 1802 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Africa. It was published by A. Arrowsmith, Rathbone Place, Nov. 1, 1802. Scale [ca. 1:6,500,000]. Covers also Cape Verde Islands and Madagascar. The image inside the map neatline is georeferenced to the surface of the earth and fit to the 'Africa Sinusoidal' projection. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, cities and other human settlements, territorial boundaries, shoreline features, and more. Relief is shown by hachures. This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection and the Harvard University Library as part of the Open Collections Program at Harvard University project: Organizing Our World: Sponsored Exploration and Scientific Discovery in the Modern Age. Maps selected for the project correspond to various expeditions and represent a range of regions, originators, ground condition dates, scales, and purposes.

Historic paper maps can provide an excellent view of the changes that have occurred in the cultural and physical landscape. The wide range of information provided on these maps make them useful in the study of historic geography, and urban and rural land use change. As this map has been georeferenced, it can be used in a GIS as a source or background layer in conjunction with other GIS data.

source map publication date.

map.

None.

The georeferenced raster is a faithfully reproduced digital image of the original source map. Some differences may be detected between the source graphic used and the raster image due to the RGB values assigned that particular color. The intent is to recreate those colors as near as possible. Data completeness for raster digital image files reflect content of the source graphic. Features may have been eliminated or generalized on the source graphic due to scale and legibility constraints The horizontal positional accuracy of a raster image is approximately the same as the accuracy of the published source map. The lack of a greater accuracy is largely the result of the inaccuracies with the original measurements and possible distortions in the original paper map document. For instance, this map contains grid-like seams that are the result of being formerly folded as a booklet. There may also be errors introduced during the digitizing and georeferencing process. In most cases, however, errors in the raster image are small compared with sources of error in the original map graphic. The Root Mean Squared (RMS) error for this map is 60008.73608 meters. This value describes how consistent the transformation is between the different control points (links). The RMS error is only an assessment of the accuracy of the transformation.

ESRI ArcGIS 9.3.

Not applicable.