How to use the command 'ogrinfo' (with examples)

‘ogrinfo’ is a command-line utility that is part of the Geospatial Data Abstraction Library (GDAL) suite. It provides functionalities for listing and inspecting geospatial data from various formats supported by OGR, GDAL’s vector library. The command is invaluable for users needing detailed information about geospatial datasets, including formats, layers, and features.

Use case 1: List supported formats

Code:

ogrinfo --formats

Motivation:

Knowing which data formats are supported by OGR is crucial for users working with diverse geospatial datasets. This information allows users to determine if their data sources can be processed using GDAL’s suite of tools. Listing supported formats can also help guide data conversion processes by informing users of the available output formats.

Explanation:

• ogrinfo: This is the command to invoke GDAL’s utility for inspecting geospatial data.
• --formats: This argument tells ‘ogrinfo’ to list all the vector data formats that the installed version of GDAL supports. It provides a quick overview, particularly useful for verifying the availability of handlers necessary to read or write specific data formats.

Example output:

Supported Formats:
  -> ESRI Shapefile
  -> GeoJSON
  -> KML
  -> CSV
  -> GPKG
  ...

Use case 2: List layers of a data source

Code:

ogrinfo path/to/input.gpkg

Motivation:

Understanding the structure of a geospatial dataset is essential for effective data analysis and manipulation. Listing the layers of a data source gives insight into its composition, indicating what types of data are available within. This step is often necessary before delving deeper into specific layers to perform detailed analysis or processing.

Explanation:

• ogrinfo: The command used for inspecting geospatial data.
• path/to/input.gpkg: This is the path to the GeoPackage file that contains the geospatial data. The given file path is the target data source from which layers will be listed.

Example output:

INFO: Open of `path/to/input.gpkg'
      using driver `GPKG' successful.
1: points_layer (Point)
2: lines_layer (LineString)
3: polygons_layer (Polygon)

Use case 3: Get detailed information about a specific layer

Code:

ogrinfo path/to/input.gpkg layer_name

Motivation:

Gaining detailed information about a specific layer within a geospatial dataset is crucial for users who need an in-depth understanding of the data structure and attributes. This use case is especially important for tasks such as data validation, preprocessing, or preparing data for analysis.

Explanation:

• ogrinfo: The command for accessing geospatial data details.
• path/to/input.gpkg: The path to the data source containing the layers.
• layer_name: The specific layer within the data source from which detailed information is sought. This argument enables users to focus on a single layer for a more detailed inspection.

Example output:

Layer name: layer_name
Geometry: Point
Feature Count: 200
Extent: (4981234, 3891234) - (5987654, 4893456)
Layer SRS WKT:
GEOGCS["WGS 84", ...
Attributes: 
  fid: Integer (0.0)
  name: String (0.0)
  ...

Use case 4: Show summary information about a specific layer

Code:

ogrinfo -so path/to/input.gpkg layer_name

Motivation:

When a quick overview of a layer’s characteristics is required, such as before an analysis or during early stages of data exploration, obtaining a summary of the layer is beneficial. This information can guide decisions about deeper data inspection or transformations needed.

Explanation:

• ogrinfo: Used for querying geospatial data.
• -so: This flag retrieves a summary of the indicated layer.
• path/to/input.gpkg: Specifies the data source.
• layer_name: Indicates which layer’s summary to display.

Example output:

Layer name: layer_name
Geometry: Point
Feature Count: 200
Extent: (4981234, 3891234) - (5987654, 4893456)

Use case 5: Show summary of all layers of the data source

Code:

ogrinfo -so -al path/to/input.gpkg

Motivation:

This use case is critical when initial evaluations of a data source need to be conducted to understand the makeup and breadth of information within multiple layers. It provides a comprehensive overview of what each layer contains and is useful for new data sources where familiarity has yet to be established.

Explanation:

• ogrinfo: Command for inspecting geospatial data sources.
• -so: Request summary information.
• -al: Indicates all layers in the data source should be considered.
• path/to/input.gpkg: Path to the GeoPackage file containing the multiple layers.

Example output:

Layer name: points_layer
Geometry: Point
Feature Count: 100

Layer name: lines_layer
Geometry: LineString
Feature Count: 150

Layer name: polygons_layer
Geometry: Polygon
Feature Count: 50

Use case 6: Show detailed information of features matching a condition

Code:

ogrinfo -where 'attribute_name > 42' path/to/input.gpkg layer_name

Motivation:

In data analysis or preprocessing scenarios, selectively querying features based on attribute conditions can save time and facilitate focused analyses. This command allows the user to filter features in a layer according to specified conditions, enabling a targeted examination of data subsets.

Explanation:

• ogrinfo: Invoked to inspect geospatial data.
• -where 'attribute_name > 42': A SQL-like syntax filter applied to select features where the attribute’s value exceeds 42.
• path/to/input.gpkg: File path to the specific data source.
• layer_name: Specifies the layer in which to apply the filter.

Example output:

Feature Count: 10
...
Feature 1: (43) point_detail1
Feature 2: (45) point_detail2
...

Use case 7: Update a layer in the data source with SQL

Code:

ogrinfo path/to/input.geojson -dialect SQLite -sql "UPDATE input SET attribute_name = 'foo'"

Motivation:

Modifying attribute values programmatically is often necessary to rectify data or prepare it for analysis. This use case demonstrates using SQL commands to update layer attributes directly, saving the need for separate database systems when executing common update operations.

Explanation:

• ogrinfo: Executes operations over geospatial datasets.
• path/to/input.geojson: Referring to the GeoJSON data where the SQL operation will take place.
• -dialect SQLite: Specifies the SQL dialect to be used, crucial for ensuring the correct interpretation of the SQL command.
• -sql "UPDATE input SET attribute_name = 'foo'": An SQL statement describing the update operation, changing the value of ‘attribute_name’ to ‘foo’ wherever applicable in the dataset.

Example output:

INFO: Updated attribute_name in layer input for selected features.

Conclusion:

Using ‘ogrinfo’ effectively enhances your ability to work with geospatial data by providing a versatile set of tools for inspecting and manipulating data sources. From listing supported formats to executing SQL operations, these examples highlight the practical ways in which ‘ogrinfo’ commands can facilitate comprehensive geospatial data management. With these capabilities, users can confidently engage with complex datasets to extract valuable insights and perform necessary data transformations.