Feature Classes, Data File Formats in ArcGIS

Feature Class A single geographic feature type (having the same spatial representation) corresponds to a feature class Feature classes in geodatabase are: Point feature class Line feature class Polygon feature class Annotation Geographic feature type (counties, roads, capitals, etc.) Collection of geographic features with same geometry type. manhole cover locations as points sewer lines parcel polygons Street name annotation

Feature Classes Annotation: Text

Data File Formats and ArcGIS Shapefile - legacy ESRI (ArcView 3.x) Coverage - legacy ESRI (ArcInfo 7.x) Geodatabase - most recent (ArcGIS 8.x onwards) Layer Type of data format (A Data Format is an implementation of a Data Structure. Examples of a data format include 'coverages', 'shapefiles' and 'grids') graphic (location and shape data) Tabular (text, numbers, or other data) Source: http://www.indiana.edu/~gisci/courses/g338/lectures/introduction-to-gis-2.html

http://www.geog.ucsb.edu/~jeff/gis/data_models1.html

Shapefile (.shp) Each shapefile corresponds to a feature class A complete shapefile comprises of at least 3 files with the same prefix name( *.shp, *.shx and *.dbf) (should be saved in a same folder) *.shp = shapefile, *.shx = header and *.dbf = associated database file Additionally, you may have a *.prj = Projection file, a *.lyr =layer, and other index files. All these files must be saved in the same workspace. Contains a single feature type. Attribute information (stored in dBASE tables) The linkage of geometric files to separate attribute tables is common to shapefiles and coverages and is called a georelational data model by ESRI. http://www.geog.ucsb.edu/~jeff/gis/data_models1.html

ArcInfo Coverages A coverage is a collection of files in a subdirectory Contains multiple geographic feature types Folder that contains all of these feature classes is the actual coverage Two folders within a workspace (one with the name of the coverage and another named ‘info’) These files contain both the graphic and tabular data Each geographical feature type corresponds to a feature class An ArcInfo coverage does not have an individual file extension. Each of the 2 folders contain multiple files. One with coverage name has various .adf files and info folder has .dat and .nit for all the coverages and grids in the workspace. The best way to manage (copy, move, delete, rename) ArcInfo coverages is with ArcCatalog or ArcInfo Workstation. Similar description with ArcInfo Grid. http://www.geog.ucsb.edu/~jeff/gis/data_models1.html

ArcInfo Coverages Icons and hierarchy.

Geodatabase (.mdb) Primary mechanism used to organize and use geographic information in ArcGIS Geodatabase is a collection of geographic datasets of various types (vector, raster, and tabular data) Can be created, accessed, managed through standard menus and ArcCatalog, ArcToolbox and ArcMap object-relational database approach for storing spatial data. A geodatabase is a "container" for holding datasets, tying together the spatial features with attributes. With shapefiles, each file can only handle one type of feature. A geodatabase can store multiple feature classes or type of features within one file (held in a common file system folder)

Geodatabase http://www.geog.ucsb.edu/~jeff/gis/data_models1.html

Layer File (.lyr) Readable directly by ArcGIS Does not contain actual geographic data Specifications for the presentation of other datasets color label properties (font, color, placements, etc.) Such presentation properties are usually time consuming to create, so a .lyr file allows these settings to be saved and shared. In order to use a .lyr file, you must also have a separate data file with the same prefix name saved in the same file space.

Icons and hierarchy Source: http://www.geog.ucsb.edu/~jeff/gis/data_models1.htm