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Definition
Information about a geographic feature in a GIS. Ex: attributes of a river might include its name, length, and average depth.
In raster datasets, attributes is info associated w/each unique value of raster cells.
Cartographic info that specifies how features are displayed & labeled on a map (ex:line thickness, length, color, and font). |
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A map element that defines a geographic extent, a page extent, a coordinate system, and other display properties for one or more layers in ArcMap. A dataset can be represented in one or more data frames.
In ArcMap's data view, only one data frame is displayed at a time;
in layout view, all a map's data frames are displayed at the same time.
Many cartography texts use the term "map body" to refer to what ESRI calls a data frame. |
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A collection of thematically similar geographic features (such as rivers, lakes, counties, or cities) that share the same geographic extent, coordinate system, and attributes. In ArcGIS, a layer references geographic data stored in a data source, such as a geodatabase feature class, and defines how to display the data.
Ex: a GIS map may have layers that include: 1)soils, 2)parcels, 3)streets |
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| Information about the content, quality, condition, and other characteristics of data. Metadata for geographic data may document its subject matter; how, when, where, and by whom the data was collected; accuracy of the data; availability and distribution information; its projection, scale, resolution, and accuracy; and its reliability with regard to some standard. |
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| The ratio or relationship between a distance or area on a map and the corresponding distance or area on the ground, commonly expressed as a fraction or ratio. A map scale of 1/100,000 or 1:100,000 means that one unit of measure on the map equals 100,000 of the same unit on the earth. |
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| A relationship based on location; that is, where features are located in relation to one another. There are four primary types of spatial relationships: distance, containment, intersection, and adjacency. |
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| The process of sorting or arranging entities into groups or categories based on their attribute values; on a map, the process of representing members of a group by the same symbol, usually defined in a legend. |
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| A type of thematic map in which a certain number of dots are used to represent a numeric attribute associated with a polygon layer. Dot density maps convey the intensity of an attribute. |
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| equal interval classification |
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| A data classification method that divides a set of attribute values into groups that contain an equal range of values. |
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| A map with symbols that change in size according to the value of the attribute they represent. For example, denser populations might be represented by larger dots, or larger rivers by thicker lines. |
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| natural breaks classification |
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Definition
| A data classification method that partitions data into classes using an algorithm, often called Jenks' optimization. The algorithm calculates groupings of data values and, possibly, a number of classes based on the smallest possible total error (the sum of absolute deviations about the class median, or alternatively, the sum of squared deviations about the class mean). Natural breaks classification is the default data classification method used by ArcGIS. |
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| The process of dividing one numeric attribute value by another in order to minimize differences in values based on the size of areas or the number of features in each area. For example, normalizing (dividing) total population by total area yields population per unit area, or density. |
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| A data classification method that distributes a set of values into groups that contain an equal number of values. |
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| A map designed to convey where things are in relation to each other. |
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| A map designed to convey information about a single topic or theme, such as population density or geology. |
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| The angle, measured in degrees, between a baseline drawn from a center point and another line drawn from the same point. Normally, the baseline points true north and the angle is measured clockwise from the baseline. |
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| A reference system used to locate geographic features on a two- or three-dimensional surface. A coordinate system is comprised of a spheroid, datum, projection, and units. Common coordinate systems are geographic (three-dimensional), in which locations are measured in degrees of latitude and longitude, and planar (also called projected or Cartesian), in which the earth's surface is projected onto a two-dimensional plane and locations are measured in meters or feet. |
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| The units in which measurements are rendered on a computer screen or on a printed map. Display units can be set as desired by the user—for example, feet, miles, meters, or kilometers could be set as the display units. |
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| The linear value added to all y coordinates of a map projection so that none of the values in the geographic region being mapped are negative. |
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| A network of longitude and latitude lines on a map or chart that relates points on a map to their true locations on the earth. |
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A method by which the curved surface of the earth is portrayed on a flat surface such as a map. This generally requires a systematic mathematical transformation of the earth's graticule of lines of longitude and latitude onto a plane. It can be visualized as a transparent globe with a light bulb at its center casting lines of latitude and longitude onto a sheet of paper. Generally, the paper is either flat and placed tangent to the globe (a planar or azimuthal projection), or formed into a cone or cylinder and placed over the globe (cylindrical and conical projections).
Every map projection distorts distance, area, shape, direction, or some combination thereof. |
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| A shape used to represent the shape of the earth. A spheroid is a three-dimensional shape obtained by rotating an ellipse about its minor axis. This is an oblate ellipsoid of revolution, also called an ellipsoid. |
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| In a general sense, an abstraction of the real world which incorporates only those properties thought to be relevant to the application at hand. It would normally define specific groups of entities, their attribute values, and the relationships between these. In GIS, it is often used to refer to the mechanistic representation and organization of spatial data; for example, the vector data model and the raster data model. A data model is independent of a computer system and its associated data structures. |
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- A raster data format that defines geographic space as an array of equally sized cells arranged in rows and columns. Each cell stores a numeric value that represents a geographic attribute (such as elevation) for that unit of space. When the grid is drawn as a map, cells are assigned colors according to their numeric values. Each grid cell is referenced by its x,y coordinate locations.
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| A collection of geographic features with the same geometry type (such as point, line, or polygon), the same attributes, and the same spatial reference. Feature classes can stand alone within a geodatabase or be contained within shapefiles, coverages, or other feature datasets. |
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| In a geodatabase, a collection of feature classes stored together that share the same spatial reference; that is, they have the same coordinate system and their features fall within a common geographic area. Feature classes with different geometry types may be stored in a feature dataset. |
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A relational database that stores geographic data. More precisely, the geodatabase is an object-oriented data model introduced by ESRI that is used to store spatial and attribute data and the relationships that exist among them. The geodatabase provides tools for creating "smart" geographic features and enforcing database integrity. A geodatabase can store feature classes, feature datasets, nonspatial tables, and relationship classes.
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| A vector data storage format for storing the location, shape, and attributes of geographic features. A shapefile is stored in a set of related files and contains one feature class |
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| A snapshot describing the geographic data contained in a data source, layer, or map. A thumbnail might provide an overview of all the features in a feature class or a detailed view of the features in, and the symbology of, a layer. Thumbnails are not updated automatically; they will go out of date if features are added to a data source or if the symbology of a layer changes. Thumbnails are created in ArcCatalog. |
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| A coordinate-based data model that represents geographic features as points, lines, or polygons. Each point feature is represented as a single coordinate pair, while line and polygon features are represented as ordered lists of vertices. Attributes are associated with each feature, as opposed to a raster data model, which associates attributes with grid cells. |
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| What are the components of a geographic coordinate system? |
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- Prime meridian (usually Greenwich)
- Datum (usually spheroid)
- angular unit of measure (degrees)
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| Name one way you can get information about the coordinate system of a dataset in ArcCatalog? |
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| You can use the Description tab or you can look at the dataset's Properties dialog box. |
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| What are the 2 most important factors to consider when choosing a map projection? |
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Definition
- The purpose of the map
- Which spatial properties you want to preserve
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| When would you use the vector data model versus the raster data model? |
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| To represent features with distinct boundaries - polygons |
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| In a geodatabase polygon feature class, which 2 fields are automatically calculated and updated? |
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| List 3 methods of adding data to a geodatabase |
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- Importing
- Loading
- Copying
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| If you wanted to combine features from different feature classes into on feature class, which method would you use? |
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Definition
| You would load them into a new, empty geodatabase feature class. |
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| How is a GIS map different from a static map? |
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| A GIS map is linked to data so you can pan, zoom, get info, etc. |
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| What is one way you can get info about a feature using Arc GIS? |
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| You can use the Identify tool to click a map feature and see its attributes. |
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| What are the primary operations that a GIS can perform that make it a useful tool for solving problems? |
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Definition
- capture
- store
- query
- analyze
- display
- present data
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| What are the 5 steps in the geographic inquiry process? |
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- Ask a geographic question
- Acquire geographic data
- Explore geographic data
- Analyze geographic information
- Act on geographic knowledge.
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