1. Spatial Data – data with a geographic location, representation, or reference point that it
describes.
2. Cartography – the science of map making, including data inclusion, layout, elements, colors, and
design. As much as it’s a science, it’s an art form.
3. Shapefile – an Esri proprietary data format for storing geographic data. Very cross-GIS
compatible, but limiting in many aspects. Often misused to mean any geographic dataset as in
“could you send me that shapefile?”
4. Layer – multiple meanings in a GIS context:
a. The distinct data elements that compose a map document, ordered one on top of the
next for GIS drawing order (top is drawn last and seen first)
b. A single data element, saved into a GIS file format along with its associated symbology.
5. Scale – the ratio of the size of elements on screen or in print on the map to their size in the real
world
6. Raster – spatial data that stores location based upon a single origin point and a data stream of
known width, height, and resolution. Often used for continuous surfaces.
a. DEM – Digital Elevation Model. A specific use case of raster data where the pixel value
represents the elevation of areas covered by the pixel. Sometime called a DTM (digital
terrain model) or DED (digital elevation dataset).
7. Vector – spatial data that stores location using Cartesian coordinate locations.
a. Point – A single spot in (usually) two dimensional space. Attributes represent only that
location (and sometimes are inferred to represent nearby locations).
b. Line (Polyline) – Multiple points connected to represent all locations in between along
the connection.
c. Polygon – Multiple polylines connected to create a boundary. Polygon zones are
generalized representations where all locations contained within the boundaries are
considered to have the same property.
8. Coordinate System/Spatial Reference – defines the origin point, coordinate space, and geoid
for a dataset’s spatial data
a. Datum – the origin point of the coordinate system and information required to
accurately define an origin, like a surface model
b. Geographic Coordinate System (GCS) – A coordinate system that specifies latitude and
longitude as coordinates
c. Projected Coordinate System – similar to and includes a GCS. “Projects”/transforms
coordinates into a new coordinates system to display a map in 2D space. Sometimes
referred to as “the projection” of a dataset.
9. Resolution – the density of data of a raster dataset or rasterized map document. Sometimes
used to mean the density of data in any dataset. For raster datasets, this value is expressed as
the length of the side of a pixel (eg: 10m pixels). For rasterized graphic formats, it is most
commonly expressed in pixels per inch of paper (ppi) or dots per inch of paper (dpi) and a good
target to reach is 300 dpi for clear prints.
10. Geoprocessing – the practice of using GIS tools to process, transform, filter, and query GIS data
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