Understanding Geodata

Understanding Geodata

Geodata, also known as GIS data, is information with a spatial reference utilized in Geographic Information Systems (GIS). These data play a crucial role in various applications, providing valuable insights into geographical elements.

Primary and Secondary Geodata

  • Primary data: This is raw information directly acquired through measurements, such as property measurements, in its unprocessed form
  • Secondary data: These are refined versions of primary data, processed through calculations, modeling, or other methods to enhance their usability.

Components of Geodata: Object Attributes and Geometries

All geodata comprise two fundamental components: object attributes and object geometries.

  • Object attributes: These describe the characteristics of an object, such as a restaurants's brand, address, and reviews.
  • Object geometries: These determine the object's position and shape, represented as points, lines, surfaces, or bodies. For instance, when using Google Maps to find restaurants, the object geometry is a point with specific coordinates.

Categories of Geodata

Geodata is further categorized based on its nature.

  • Geospatial base data: Official and fundamental data used as a foundation for specialized and thematic maps, including topography, property data, and information from surveying administrations.
  • Geo-technical data: Data from various specialties, crucial in urban planning, environmental protection, demography, and more.

Storage Formats for Geographic Information

  • in a database e.g. PostgreSQL
  • as shapefile
  • in a geodatabase
  • as a raster image
  • as table data

Geographic information can be stored in various formats:

  • Geodatabase: E.g. PostgreSQL.
  • Shapefile: A common format for storing vector-based geospatial information.
  • Raster image: A format using grids of cells to represent information.
  • Table data: Tabular data storing information in rows and columns.

Acquiring Geodata: Public and Private Sources

Geodata can be obtained from both public and private providers. Public entities, like the State Office for Digitization, Broadband, and Surveying, may offer aerial photos and topographic maps with legal restrictions and varying costs.

Quality Considerations: Ensuring Fitness for Purpose

The quality of geodata is critical, depending on its application:

  • Accuracy: Varies according to the object's dimensions; precision proportional to the object's size is essential.
  • Logical consistency: Ensuring data consistency, for instance, avoiding negative values in population mapping.
  • Temporal dimension: Acknowledging time as a critical factor, especially in historical data or analyzing population structures over time.

Conclusion: Geodata as a Decision-Making Medium

In conclusion, geodata represents real-world objects with attributes and geometries. Its primary and secondary forms are stored in various formats, serving as the backbone for GIS analysis. Understanding the quality considerations is paramount for effective decision-making in diverse fields. Geodata is not just information; it is a powerful tool for spatial analysis and decision support.

First published August 30, 2020

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