Chapter 2 — Data Formats

2.1 Vector Data File

a) GeoJSON

An example of a FeatureCollection that includes a point, line and polygon geometry with some attributes stored as properties:

  { "type": "FeatureCollection",
    "features": [
      { "type": "Feature",
        "geometry": {"type": "Point", "coordinates": [102.0, 0.5]},
        "properties": {"prop0": "value0"}
        },
      { "type": "Feature",
        "geometry": {
          "type": "LineString",
          "coordinates": [
            [102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [105.0, 1.0]
            ]
          },
        "properties": {
          "prop0": "value0",
          "prop1": 0.0
          }
        },
      { "type": "Feature",
         "geometry": {
           "type": "Polygon",
           "coordinates": [
             [ [100.0, 0.0], [101.0, 0.0], [101.0, 1.0],
               [100.0, 1.0], [100.0, 0.0] ]
             ]
         },
         "properties": {
           "prop0": "value0",
           "prop1": {"this": "that"}
           }
         }
       ]
     }

b) GeoPackage

Its filename usually ends in .gpkg. Applications such as QGIS, R and ArcGIS will recognize this format.

c) Shapefile

The shapefile format is a geospatial vector data format for geographic information system (GIS) software.

The list of files that define a “shapefile” is shown in the following table. Note that each file has a specific role in defining a shapefile.

shp files

d) File Geodatabase

A file geodatabase (.gdb folder) is a relational database storage format. It’s a far more complex data structure than the shapefile and consists of many files. An example of the contents of a geodatabase is shown in the following figure.

2.2 Raster Data File Formats

Rasters are in part defined by their pixel depth. Pixel depth defines the range of distinct values the raster can store. For example, a 1-bit raster can only store 2 distinct values: 0 and 1.