Spatial data

Data types
Acquiring digital data
Creating digital data sets

Creating a GIS involves data capture, verification and processing. Geographical data exist as maps, aerial photographs, satellite images or tables. This means that a spatial database can be created by:

• getting hold of data that is already in digital format from a data supplier
  
  
• digitising information from map data
  
  
• doing a survey to collect geographical entities eg a field survey
  
  
• interpolating from point observations to create surfaces of continuous data
  

Common forms

• Paper or digital topographic or thematic maps. These are at a specific scale and locations of objects or entities are specified by a specific coordinate system.
  
  
• Digital images. These are at many temporal and spatial scales.
  
  
• Ground survey. These are usually point data.