datum

error unknown tag plural data · error unknown tag plural datums

1. Something known or assumed as fact, and is made the basis of reasoning or inference which an intellectual system of any sort (such as knowledge or theoretical framework) is constructed.

   a datum of experience

   1 more example

   given this datum, it follows that

2. singularSingular of data: A single recorded phenomenon, especially obtained by scientific work.

   Holonym: data set

   Synonyms: data point

3. businessA point, line, plane, or surface with reference to which positions (such as elevations) are measured or indicated. (Examples include a permanent benchmark in leveling or mean sea level in a topographical survey).

   A geodetic datum is sometimes also called a benchmark.

   4 more examples

   GD&T tells us that the center of a bolt circle is in fact defined by the locations of the holes themselves, as each is a datum.

   In a strict sense, a tidal datum can be understood as the reference plane (or surface) to which the height of a predicted tide is referred.[…]Sounding and chart datums are low water datums, that is, they refer to the level of the water surface at low tide. Nonetheless, there are also datums based on high water levels.[…]These two different datums may be included in the broader category of vertical datums, which comprises any plane or surface used as a reference to measure vertical distances (such as depths, drying features, heights on shore, etc.).

   2000, Nuno Sergio Marques Antunes, “The Importance of the Tidal Datum in the Definition of Maritime Limits and Boundaries”, in Maritime Briefing, volume 2, number 7, International Boundaries Research Unit, University of Durham, page 5

   Datums are another important map aspect related to projection. A datum provides a base reference for measuring locations on Earth's surface.

   2007, Roger F Tomlinson, Thinking about GIS: geographic information system planning for managers

   For horizontal measurements [on the Earth], we fix a mathematical body of Earth in space using a Cartesian coordinate system. After that, a separate coordinate system is created over the surface of this body to generate horizontal coordinates. A mathematical earth body fixed in space makes up the horizontal datum.

   2012, Yong-Qi Chen, Yuk-Cheung Lee, chapter 2.3, in Geographical Data Acquisition

4. nauticalA floating reference point, or SLDMB, used to evaluate surface currents in a body of water, and often employed by coastal search and rescue.

present singular third person datums · participle present datuming · participle past datumed · past datumed

1. To provide missing data points by using a mathematical model to extrapolate values that are outside the range of a measuring device.

   On the left the stacking velocity functions are datumed to sea level and show great disparity.

   1998, Stuart Fagin, Model-based Depth Imaging, →ISBN, page 164

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   Removing the effects of any period of deformation by datuming or flattening selective reflection horizons should restore the structure prior to the datumed horizon, or the amount of deformation above the datumed horizon.

   1982, Paul M. Tucker, Pitfalls Revisited - Issue 3, →ISBN, page 6

   On the other hand, if we have a sufficiently accurate near-surface velocity model, we may apply wavefield datuming to convert the raw data into new data as if they were recorded along a datum below the near surface (Box 2.3).

   2014, Hua-Wei Zhou -, Practical Seismic Data Analysis, →ISBN, page 62