English

In ECDIS, a feature schema which provides a description of real world entities. It contains a list of FEATURE OBJECT classes (each relating to a real world entity), ATTRIBUTES and allowable ATTRIBUTE VALUES.

In ECDIS, the mode in which information on the ECDIS is being presented. Typical modes include: north-up - as shown on a nautical CHART, north is at the top of the display; Ship’s head-up - based on the actual HEADING of the ship, (e.g. Ship’s gyrocompass); course-up display - based on the COURSE or ROUTE being taken.

In ECDIS, to display the chart information at a DISPLAY SCALE larger than the COMPILATION SCALE. Overscaling may arise from a deliberate overscaling by the mariner, or from automatic overscaling by ECDIS in compiling a DISPLAY when the data included is of various NAVIGATIONAL PURPOSES.

In ECDIS, a 2-dimensional data structure in which the geometry is described in terms of NODES and EDGES which are TOPOLOGICALLY linked. A special case of a CHAIN-NODE data structure in which edges must not cross. CONNECTED NODES are formed at all points where edges meet.

In ECDIS, a DISPLAY in which OWN SHIP remains stationary, while all other charted information and targets move relative to own ship’s position. See also TRUE MOTION DISPLAY.

In ECDIS, the pre-determination of COURSE, speed, WAYPOINTS and radius in relation to the waters to be navigated, and in relation to other relevant information and conditions.

A graduated line on a MAP, PLAN, PHOTOGRAPH, or MOSAIC, by means of which actual ground distances may be determined. Also called GRAPHIC SCALE or LINEAR SCALE. In ECDIS, a vertical bar scale of 1 nautical mile divided into 1/10ths, intended to convey an immediate sense of distance.

In ECDIS, SYMBOLS designed specifically for fast draw and to give the maximum clarity under all conditions of viewing the CRT. They are less complex than the equivalent paper CHART SYMBOLS.

In ECDIS, the implemented term used in the IHO transfer standard data structure for a spatial object (i.e. a SPATIAL OBJECT as defined in the data model is encoded as a spatial record in the data structure). There are three types of spatial records: VECTOR, RASTER and MATRIX.

In ECDIS and digital data, the set of properties of geometric forms (such as connectivity, neighbourhood) which is defined with the DATA MODEL remaining invariant when subject to a continuous transformation.

In ECDIS, in conjunction with ROUTE PLANNING, a geographical location (e.g. latitude and longitude) indicating a significant event on a vessel’s planned route (e.g. course alteration point, calling in point, etc.).

Observed depth including all corrections related to the survey, post processing, and reduction to the appropriate vertical datum. See Correction of Soundings, Reduction of Soundings.

Component of total propagated uncertainty (TPU) calculated in the horizontal dimension. THU is a two-dimensional quantity with all contributing horizontal measurement uncertainties included.

Component of total propagated uncertainty (TPU) calculated in the vertical dimension. TVU is a one-dimensional quantity with all contributing vertical measurement uncertainties included.

Estimate characterising the range of values within which the true value of a measurement is expected to lie as defined within a particular confidence level. It is expressed as a positive value.