A gazetteer is a geographic index or dictionary that helps you identify the geographic location associated with a place name.
A Gazetteer Metadata Service is a special type of ArcIMS Metadata Service that lets you provide a gazetteer that is appropriate to use when searching your metadata catalog. Searching a Gazetteer Metadata Service by place name returns the places in the gazetteer with a related name. Searching it by your area of interest returns the gazetteer places in that area.
ArcIMS comes with an ArcIMS Gazetteer disk. It has a world gazetteer dataset that contains approximately 350,000 place names and geographic features from around the world. It contains a complete list of all countries, large- and medium-sized cities, major water bodies, and mountain ranges, plus other geographic features. This dataset contains more detailed places within the United States such as small cities, ZIP Codes, some historical places, and parks. The global scope of this data lets you use it with any Metadata Service.
However, its global scope means that it might not include detailed places and features that people might use when searching your metadata service. You can add places to an existing Gazetteer Metadata Service using ArcGIS Desktop. First, create data defining the places to add to your gazetteer, then load them into the service using the tool provided with ArcCatalog.
The ArcIMS gazetteer data has been provided on the ArcIMS Gazetteer disk in shapefile format. If you want to use a subset of this data as the base for your gazetteer, you can export only the places you want to use from these shapefiles using standard tools in ArcGIS. Then, load the exported places into your Gazetteer Metadata Service.
After loading new places, the gazetteer service's text indexes must be updated to include the new place names.
Defining custom gazetteer places
For an ArcIMS Gazetteer Metadata Service, new places can be defined in any table or feature class supported by ArcGIS—use the format most convenient for you. You can use several tables or feature classes to store different types of places.
A gazetteer place is defined by providing the following information. Store each piece of information in a separate field.
A place name—One or more keywords that can be used to search for a place. Typically the place name is the name of a country, city, river, landmark, or any geographic feature for which users will be able to search. There should be one row in the table or feature class for each place; for example, one record for Japan, one for San Francisco, one for Lake Ontario, and so on.
The place name can consist of several keywords separated by spaces. For example, the place name New York Big Apple would let users find New York City whether they searched for New York or Big Apple. Keywords are not case sensitive.
A description of the place—A statement clearly identifying the place. The description is shown in the search results and must help users select the place in which they are interested. For example, if you search with the word Paris with the ArcIMS gazetteer data, you will find 67 places with that name, including Paris, Ile-de-France, France, and Paris, Oregon, United States.
The description should indicate the type of feature, such as an airport, lake, glacier, or historical location of a city, as in the following examples:
- Paris (historical), Oregon, United States
- Zephyr, 24K Quadrangle, United States
- Allingham Creek, River, Australia
- Toronto Island, Airport, Canada
- Koldukvislarjokull, Glacier, Iceland
A rank, or sorting order, of the place—A value from 1 to 25, where a value of 1 indicates the highest rank. When a gazetteer search finds many places, higher-ranked places will appear at the top of the list.
The geographic location of the place—Either a shape representing the place or four coordinates defining the place's extent.
When places are defined in a table, the bounding box must be defined by specifying the minimum x-, minimum y-, maximum x-, and maximum y-coordinates for the extent. Each value must be stored in a separate field. When places are defined in a feature class, the bounding box of each shape will be calculated and loaded into the database; the shape itself won't be used. Alternatively, you can define the exact bounding coordinates to be used for each shape in the same manner as for tables; you might choose this option if you add gazetteer information to a feature class that is primarily used for another purpose.
The Gazetteer Metadata Service stores places in decimal degrees. Feature classes must have a spatial reference defined. For instance, shapefiles must have an associated .prj file. When new places are loaded into the service, they will be transformed to decimal degrees if the feature class uses a different spatial reference. When a table is used, the coordinates for the bounding box must be specified in decimal degrees.