- [American Standard Code for Information Interchange] The predominant
character set encoding of present-day computers.
- A rectangular area in Raster space, in which a single pixel value is filled.
- In GeoTIFF, a code is a value assigned to a GeoKey, and has one of 65536
- Coordinate System:
- A systematic way of assigning real (x,y,z..) coordinates to a surface or
volume. In Geodetics the surface is an ellipsoid used to model the earth.
- a mathematical approximation to all or part of the earth's surface.
Defining a datum requires the definition of an ellipsoid, its location and
orientation, as well as the area for which the datum is valid.
- Device Space
- A coordinate space referencing scanner, printers and display devices.
- 8-byte IEEE double precision floating point.
- A mathematically defined quadratic surface used to model the earth.
- European Petroleum Survey Group.
- For an ellipsoid with major and minor axis lengths (a,b), the flattening is
f = (a - b)/a
- For the earth, the value of f is approximately 1/298.3
- An image is geocoded if a precise algorithm for determining the
earth-location of each point in the image is defined.
- Geographic Coordinate System:
- A Geographic CS consists of a well-defined ellipsoidal datum, a Prime
Meridian, and an angular unit, allowing the assignment of a Latitude-Longitude
(and optionally, geodetic height) vector to a location on earth.
- In GeoTIFF, a GeoKey is equivalent in function to a TIFF tag, but uses a
different storage mechanism.
- An image is georeferenced if the location of its pixels in some model space
is defined, but the transformation tying model space to the earth is not known.
- A standard for storing georeference and geocoding information in a TIFF 6.0
compliant raster file.
- A coordinate mesh upon which pixels are placed
- Institute of Electrical and Electronics Engineers, Inc.
- In TIFF format, an Image File Directory, containing all the TIFF tags for
one image in the file (there may be more than one).
- Arc of constant longitude, passing through the poles.
- Model Space
- A flat geometrical space used to model a portion of the earth.
- Lines of constant latitude, parallel to the equator.
- A dimensionless point-measurement, stored in a raster file.
- Petrotechnical Open Software Corporation.
- Prime Meridian:
- An arbitrarily chosen meridian, used as reference for all others, and
defined as 0 degrees longitude.
- A projection in GeoTIFF consists of a linear (X,Y) coordinate system, and a
coordinate transformation method (such as Transverse Mercator) to tie this
system to an unspecified Geographic CS..
- Projected Coordinate System
- The result of the application of a projection transformation of a
Geographic coordinate system
- Raster Space:
- A continuous planar space in which pixel values are visually realized.
- In TIFF format, a RATIONAL value is a fractional value represented by the
ratio of two unsigned 4-byte integers.
- The USGS Spatial Data Transmission Standard.
- In TIFF format, a tag is packet of numerical or ASCII values, which have a
numerical "Tag" ID indicating their information content.
- Acronym for Tagged Image File Format; a platform-independent, extensive
specification for storing raster data and ancillary information in a single
- US Geological Survey
END OF SPECIFICATION