GIS Data Formats: Vector vs. Raster

Geographic Information System (GIS) data formats are essential for storing and managing spatial information. The most common GIS data formats are vector and raster formats. 

Vector data represents geographic features using geometric shapes such as points, lines, and polygons. Each feature has additional information (so-called attribute data), such as names or types, stored in a table.

• Points: Represent specific locations (e.g., a building or a tree)
• Lines: Represent linear features (e.g., roads, rivers)
• Polygons: Represent area features (e.g., lakes, land parcels)

 Out of the three vector shapes mentioned above, only polygons have an area.‍

Raster data represents geographic information as a grid of pixels, each containing a value that reveals information such as color, temperature, or elevation. The resolution of raster data is defined by the size of the pixels (e.g., one pixel = 10x10m → 10m resolution); higher resolution provides more detail but requires more storage space. Different from vector, raster is well-suited for continuous data, such as satellite images, aerial photography, and elevation models.  

Unlike vector data, raster data allows for multiple bands, which refer to layers of data for each pixel. For example, a single-band raster might represent elevation values, while a multi-band raster could include different wavelengths of light (e.g., red, green, and blue) for satellite imagery. Each band contains unique information and can be combined to create composite images or perform analyses.

Common Data Formats

Vector data formats like Shapefiles, GeJSON, and KML store geographic features with attribute data, i.e., properties or characteristics of spatial features.  

• GeoJSON (.geojson) is the most commonly used vector data format. It is an open standard format that uses JavaScript Object Notation (JSON) to encode a variety of geographic data structures.
• Shapefile (.shp): Stores geometric location and attribute information of geographic features. It consists of at least three mandatory files: .shp (geometry), .shx (shape index), and .dbf (attribute data). Thus, it is commonly distributed as a zip due to several files. It is a proprietary standard managed by ESRI.
• KML/KMZ: Keyhole Markup Language files (.kml) or compressed KML files (.kmz) display geographic data in Google Earth. It is a proprietary standard managed by Google.

Raster data formats like GeoTIFF are used for imagery and grid-based data.

• GeoTIFF (.tif or .tiff): A GeoTIFF allows georeferencing information to be embedded within a TIFF (Tagged Image File Format) file. A TIFF is a flexible and adaptable raster image format that supports the inclusion of multiple types of data in a single file, such as image data, layers, and tags (e.g., geodata).

Please note that you can only upload an asset into Maya in vector format (all mentioned above) and that the exports are made available in raster format as a GeoTIFF.

When to use what?

To determine when to use vector data and when to use raster data, you need to consider the type of geographic features and the requirements for scalability and precision.

Vector data works better for large coherent areas but not as well for complex shapes. For example, if you need to represent a large, simple area like a square the size of Africa, a vector format is more efficient because it can represent the area with simple shapes and does not need to store data for each individual pixel within the area.

Raster data, on the other hand, works better for detailed and complex shapes but not as well for large areas. For example, if you need to represent a detailed and complicated area like mangroves in a river delta, a raster format is better because it can accurately show the fine details and variations in the area.

Written by Delphine-Marie Zacharias 🧡