Data drives all cartography- without it, maps couldn’t be made. There are countless types of data- each delivering their own unique value and insights. However, all types of mapping data fall into one of two categories: Vector Data or Raster Data. We spoke with Geospatial Analyst, Kelli Hercules, about why raster and vector data are important, how they differ, and their respective benefits when it comes to displaying specific data.
“Vector data is made up of points, lines, and polygons; all of which are used to represent real-world features in maps. All geometry types store information in x/y coordinates.
For EVG’s use of vector data:
- Point data usually represents small features, such as small buildings, pylons, landmark significant features.
- Line data represents features, such as: transportation (roads, cart tracks, trails), rivers, cables, pipelines.
- Polygon data represents features, such as: land cover, area hydrography, large buildings, city/county/state/country boundaries.
(Image courtesy of firenorth.org.au)
Raster data is made of pixels that are compiled into rows and columns. Primarily you will see raster data used in digital aerial photographs, satellite imagery, or even digital pictures. However, raster data can be organized into two separate categories, discrete data & continuous data.
- Discrete rasters are easy to distinguish as the data is organized into themes. Where one value might represent land cover, another may represent a river.
- Continuous rasters represent values that are above/below sea level. Digital elevation models are a good example of continuous raster data.”
How does this apply to your work at EVG?
“Both raster and vector data are important for our day to day tasks here at East View Geospatial. When we source data in-house, the data would be procured as a vector (points, lines, and polygons). This data is amassed in four different areas/themes: Hydrography, Transportation, Culture, and Land Cover. These two data types can also be utilized simultaneously. Raster data is necessary for feature data collection, in which the data being collected is vector data. Whether we procure our data or use data from other sources, vector and raster data are at the core of what we do here at East View Geospatial.”
Raster data and vector data are the base of all things geospatial. At the most granular level, all datasets will either be a raster dataset or vector dataset. With the cartographic process becoming almost 100% digital, it is crucial for cartographers to fully understand the differences and nuances of both types of data.
Kelli Hercules, Geospatial Analyst