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Rasters and Vectors

Vector and raster are the two main digital formats used to represent spatial geographic data. This documentation aims to provide users with basic knowledge to understand the fundamental file types commonly handled in GIS software such as GEO4X.

🗺️ What Is a Raster Layer?​

Raster data represents the world through images.

These images consist of a grid of cells called pixels, organized in rows and columns. Each pixel stores specific values.

✅ Examples of Raster Layers

  • DEM / DTM: Each pixel stores the elevation value at the coordinates corresponding to the pixel.
  • Photograph / Orthophotograph: Each pixel stores RGB color values representing the color at the pixel’s coordinates.
  • Thermal Maps: Each pixel stores temperature values measured at the pixel’s coordinates.

🔍 Key Characteristics

  • Spatial resolution: the real-world area covered by a single pixel
  • File size: can be very large depending on the resolution and geographic extent
  • Formats: GEOTIFF, TIFF

🛠️ Main Use

Raster data is particularly well-suited for representing continuous data such as elevation, temperature, vegetation, etc.

💡 Rasters are also commonly used to create binary masks (presence/absence) or to convert point data into surfaces for spatial analysis.

📌 What Is a Vector Layer?​

A vector layer has two components: an attribute component (associated information) and a graphic component (its shape or geometry).

The attribute component of a vector is descriptive. A vector is associated with specific data.

The graphic component of a vector is made up of nodes (points in space) and mathematical formulas used to calculate arcs (lines) that connect these nodes and form a geometry.

✅ Examples of Vector Layers

  • Points: trees, wells, buildings
  • Lines: roads, rivers
  • Polygons: parcels, industrial zones, forests, lakes

🔍 Key Characteristics

  • Precision and scalability: features are defined by mathematical relationships, allowing for infinite zoom without quality loss
  • Lightweight files: file size depends mainly on the number of features and attribute data
  • Formats: .shp, .geojson, .kml, .gpkg, .csv

🛠️ Main Use

Vector layers are ideal for representing discrete objects with clearly defined boundaries: infrastructure, administrative boundaries, point-based inventories, or cadastral data.