25 February 2010

Spatial and Geospatial

Often my students ask about the difference(s) between spatial and geospatial. These two words appear very frequently in remote sensing and GIS literature.

The word spatial originated from Latin 'spatium', which means space. Spatial means 'pertaining to space' or 'having to do with space, relating to space and the position, size, shape, etc.' (Oxford Dictionary), which refers to features or phenomena distributed in three-dimensional space (any space, not only the Earth's surface) and, thus, having physical, measurable dimensions. In GIS, 'spatial' is also referred to as 'based on location on map'.

Geographic(al) means 'pertaining to geography (the study of the surface of the earth)' and 'referring to or characteristic of a certain locality, especially in reference to its location in relation to other places' (Macquarie Dictionary). Spatial has broader meaning, encompassing the term geographic. Geographic data can be defined as a class of spatial data in which the frame is the surface and/or near-surface of the Earth. 'Geographic' is the right word for graphic presentation (e.g., maps) of features and phenomena on or near the Earth's surface. Geographic data uses different feature types (raster, points, lines, or polygons) to uniquely identify the location and/or the geographical boundaries of spatial (location based) entities that exist on the earth surface. Geographic data are a significant subset of spatial data, although the terms geographic, spatial, and geospatial are often used interchangeably.

Geospatial is another word, and might have originated in the industry to make the things differentiate from geography. Though this word is becoming popular, it has not been defined in any of the standard dictionary yet. Since 'geo' is from Greek 'gaya' meaning Earth, geospatial thus means earth-space. NASA says 'geospatial means the distribution of something in a geographic sense; it refers to entities that can be located by some co-ordinate system'. Geospatial data is to develop information about features, objects, and classes on Earth's surface and/or near Earth's surface. Geospatial is that type of spatial data which is related to the Earth, but the terms spatial and geospatial are often used interchangeably. United States Geological Survey (USGS) says "the terms spatial and geospatial are equivalent".

Excerpted from my book Remote Sensing and GIS

1 comment: