Entity with a well defined boundary and identity that encapsulates state and behaviour.

Optical element that receives light from the object and forms the first or primary image of an optical system.

Act of measuring or otherwise determining the value of a property.

Method, algorithm or instrument, or system of these, which may be used in making an observation.

Formal representation of phenomena of a universe of discourse with an underlying vocabulary including definitions and axioms that make the intended meaning explicit and describe phenomena and their interrelationships.

The OGC is a non-profit, international, voluntary consensus standards organization that is leading the development of standards for geospatial and location based services.

A standard that has members of the GIS user communities cooperatively working to correct and improve spatial data and attributes in exchange for less restrictive uses of the data.

A program in which the source code is available to the user for their use and/or modification from its original design free of charge. Open source code is typically created as a collaborative effort in which programmers improve upon the code and share the changes within the community. The result of this collaboration is the fast and affordable development of high quality technologies and software products.

Transparent access to mixed geodata and geoprocessing resources in a networked environment.

Specification of a transformation or query that an object may be called to execute.

Scale which provides a basis for measuring only the relative position of an object.

Image in which by orthogonal projection to a reference surface, displacement of image points due to sensor orientation and terrain relief has been removed.

Digital or digitized aerial photographs in which the pixels are geometrically rectified and given geographical references. The data structure is raster. An orthophoto map may include details of topography and names.