About THL > Introductions > Maps Resources > Maps Introduction
Maps Introduction
We offer dynamic GIS-mapping integrated with our Place Dictionary as well as an archive of static historical and contemporary maps. THL's comprehensive online interactive map of the entire region allows you to zoom in and out to explore the world, while turning various layers off and on, and being able to click sites in the region to access descriptions and associated resources from the Place Dictionary. You can also change the language of toponyms, including Tibetan, Chinese, and Nepali. This dynamic resource is accompanied by our map collections, which offer a variety of static maps that are both scanned historical maps and custom made maps from our own data. Each map can be seen in its own right, but also overlaid on the GIS interactive map, and then made transparent to compare to contemporary data. In addition, we offer a limited number of specialized multimedia maps that offer rich visual platforms for exploring specific sites.
General Background on Maps
Maps in our present context are geographic maps, namely visual representations of the world in which we live, whether these are physical sites we all perceive or distinctive sites that are unique elements of specific religions and cultures, such as pure lands, heavens, or hells. It is often stressed that maps are representations of reality, or visual arguments, and thus are pervaded in their details by the presumptions and agendas of those who sponsor, create, and disseminate them. Whether the map in question is historical or contemporary, its scope, orientation, scale, symbology, colors and shape, labels, and so forth are thus all of great significance in helping us interpret the goals and position of the people and organizations involved in producing that map. The study of historical maps thus are both essential for helping us understand the location and names of specific places in specific times, but also in helping us understand the agendas and interpretative schemes of those who originally produced them.
Making maps has a long history in the world, as recognized by the field of cartography, which is the study and practice of making maps. The practitioners of this art are responsible for the aesthetic dimension of maps, the clarity of presentation for the often extraordinarily dense information being represented, and the highlighting of information and purpose which underlay a specific map. In modern terms, computers and digital resources have become an indispensable element of map making as enshrined in the rise of GIS (Geographical Information Systems). GIS refers to digital systems that organize geographical information by latitude, longitude, and altitude, and enable complex analysis and representation through use of the data. Thus, for example, if one has the right data sets in a GIS system, one could inquire into the changing nature of monasticism during a given time period, through analyzing what monasteries of what sects are founded at what time, as well as querying about the spatial relationship of each group of monasteries in relationship to surrounding environmental features as well as the location of different types of political formations. As long as all the data is in the GIS system, and keyed to a spatial footprint, astonishingly complex queries and automated cartographic representations can be generated in rapid fashion. Despite the power of GIS, though, the ancient skills of cartographers - enabling beauty, clarity, and rigor in the service of powerful argumentation and visualization - remain essential both in the GIS system itself, as well as generating static maps out of those resources.
Maps, and GIS, if often talked about in terms of “points,” “polygons,” and “lines” - a village may be a point or dot on a map, a nation or kingdom may be represented instead by a polygon or shape, while a river may be a line. Of course every point on a map is in reality a polygon, and on a large enough scale, would be represented as such, just as each line representing a river is in effect also a very elongated polygon. But for visual purposes of clarity, representing geographical features as points, polygons, and lines is essential. In addition, “topography” can signify, in some circles, the elevation contours, or the three dimensional shape of the earth’s surface. A map with topographic elements thus represents this through “contour lines” and other means. Against this background, maps often involve the use of a symbology, namely a conventional set of signs or symbols used to visually indicate different types of geographical features, such as different colors for different types of roads, or a particular kind of symbol for a specific kind of monastery. In addition, specific types of geographic features are also often given “labels”, which provide the toponyms, or place names. As the number of labels increase, label placement becomes crucial for preserving clarity. Finally a “legend” is often included with maps that decodes the symbology, as well as other framing aspects of the map.
Basic Terminology
Understanding a few basic terms will be of great utility in assessing and enjoying historical and contemporary maps. To start with a “feature” is short hand for “geographic features”, which signifies anything that can be located on the surface of the world in relatively stationary fashion - a mountain, lake, television tower, nation, county, monastery, village, and so forth. “Orientation” signifies how a map’s directions are related to the compass directions of the actual world - north, south, east, and west. While in contemporary times it is common for maps to represent the top of maps as being in the north, historical maps and specific types of maps often involve other orientations.
“Geometry” or “GIS” typically signifies latitude and longitude, which are numbers that provide a unique location on the world’s surfaces. Latitude is the geographic coordinate that specifies how far a site is to the north or south of equator, while longitude is the geographic coordinate that measures how far a site is to the east or west of a line known as the “prime meridian” that passes through the Royal Observatory in Greenwich in England. Latitude and longitude values traditionally are expressed in degrees, minutes, and seconds (DMS), but modern digital systems typically instead use decimal degrees to express the physical location of a site.
However, a latitude and longitude, while enabling precise location of a site on a perfect model of the world’s curved surface (such as a globe), are problematic when using a map, which is flat representation of the earth’s curved surfaces. In order to enable the world’s curved surface to be represented on the flat plane of a map, one has to perform what is called a “projection”, which is essentially a method of representing the surface of a sphere or other shape on a plane. Such a process distorts the surface in some fashion, but each projection preserves some aspects of the earth’s surface while distorting other aspects, such as area, shape, direction, bearing, distance, and scale. Thus a variety of map projections exist, each relating to a different purpose and agenda. In assessing data sets and maps, thus, it is important to know the projection that was used, each of which typically goes by a specific name. The most famous map projection is the Mercator projection, originally designed as a form of nautical chart.
Just as importantly is “scale”, which reflects the correspondence of distance on a map to distance in the real geography it is representing. This is expressed as a ration such as 1:10,000, meaning that 1 of any unit of measurement on the map corresponds exactly, or approximately, to 10,000 of that same unit on the ground. Thus one centimeter on the map corresponds to 10,000 centimeters on the ground. “Large scale” maps, such as 1:10,000, thus cover small regions in considerable detail, such as a town or township, which can be of use for a tourist or hiker navigating a specific place. In contrast, a “small scale” maps, such as 1:10,000,0000, cover large regions in much less detail such as a nation or continent, which can be useful for a tourist or student. Typically 1:100,000 is considered medium scale. The nomenclature of “large” and “small” can be confusing - it derives from the earlier practice of writing these as fractions, such that 1/10000 (1:10,000) is larger than 1/10000000 (1:10,000,000). Maps do not usually strictly adhere to accuracy in scale, since specific geographical features are exaggerated in order to make them clear such as the width of a road or stream.
On the digital side of things, it can be helpful to keep in mind the distinction between “raster” and “vector” images. In simplified terms, a “raster image” is what we typically think of as a digitized image, such as a digital photo or scanned map. All of the rich visual detail is preserved through the use of thousands of individual pixels on the computer screen, but the file is also large and cumbersome, and its various components are not easily manipulated or understood in a computer context. In contrast, vector graphics uses geometrical primitives such as points, lines, curves, or polygons to represent images based upon mathematical equations; they are small smaller in file size, and more easily analyzed in a computer context. Analogously, think of PDF of a text as a raster image, and a word processing document as a vector image. More relevantly, if you have a historical map, the first step would be to scan it and thus create a raster image, while if one would then go through and trace certain elements such as the location of villages and rivers, you could create a derived vector image out of that raster image.
Finally, in relationship to historical maps, one must understand “georectificaton.” In simple terms, georectification is taking a map and correlating it to the physical geometry of the world, such that the map can be overlaid, for example, on a modern GIS representation of the world. Georectification is done by assigning each pixel (picture element) in the image a separate latitude and longitude coordinate. Practically speaking, one accomplishes this by finding features in a historical map for which one has a latitude and longitude, and then extending that to correlate the entire map. Obviously this involves a certain degree of distortion since the irregular character of historical maps entails that there is a precise one to one correspondence with a given map is simply not possible, such that georectification provides varying degrees of utility.