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ArcGIS Pro Introduction

How GIS Works

GIS LayersArcGIS Pro uses the concept of a Geographic Information System (GIS) to build maps in which each category of spatial feature is a separate layer. The layers are spatially "georeferenced" so when the user overlays them the program can line them up correctly  to build and symbolize a map or analyze relationships between them. 

The first three types of layers listed below are called "vector layers" or "feature layers" and contain individual features that the program can distinguish.

  • Point (e.g., landmarks, cities on a small-scale map).  Zero-dimensional.

  • Line, or arc (e.g., roads, streams, railroads, power lines). One-dimensional.

  • Polygon (e.g., political entities, census geographies such as tracts). Two-dimensional.

  • Raster images (e.g., an aerial photograph, scanned topographic map, or remote sensing imagery such as elevation data).  Contrasting with feature-based vector layer, these are images based on an X by Y grid of cells, each of which has a value that represents something like elevation, land use classification, or color value.

Data is associated with the spatial features, and can be mapped or analyzed:

  • There can be attributes, or tabular data, associated with each feature in a layer (e.g., demographic data for each Census Tract).

  • Join your own data: Data tables (e.g., database or spreadsheet files) can be added ("joined") to a layer if there is a field with common values (e.g., census tract number).

  • Plot XY data: The program can also map data files in some spreadsheet and database formats if some fields contain geographic coordinates). 

  • Geocode addresses: Tables that contain address data can be "geocoded" to map the locations address locator reference files.

  • Georeference images: Users can open a non-referenced raster image and georeference it in ArcGIS Pro, and sometimes can vectorize features from a raster image.

You can also add your own information to a map with drawing and writing tools.