SWE Common Data Model OGC 08-094r1
Examples
Biological or chemical species data is usually represented by a categorical data component that can leverage on existing controlled vocabulary.
A camera mode can be represented by a categorical value – AUTO_FOCUS, MANUAL_FOCUS, etc…
Requirement
http:www.opengis.netspecSWE2.0reqcorecategorical-rep-valid
Req 3. A categorical representation shall at least consist of a category identifier and
information describing the value space of this identifier.
The “Category” data type detailed in clause 7.2.6 is used to define a data component with a categorical representation.
6.2.3 Numerical continuous
Perhaps the most used representation of a property value, especially in the science and technical communities, is the numerical one, as the majority of properties measured by
sensors can be represented by numbers.
Numerical representation is often used for continuous values and, in this case, the representation consists of a decimal often floating point number associated to a scale or
unit of measure. The unit specification is mandatory even for quantities such as ratios that have no physical unit in this case a scale factor is provided such as 1, 1100 for percents,
11000 for per thousands, etc..
Examples
Temperature measurements can be represented by a number associated to a unit such as degrees Celsius or Fahrenheit – 23.51°C, 94°F
A velocity vector is composed of several values usually 2 or 3 associated to a unit of speed – [1.0 2.0 3.0] ms.
Requirement
http:www.opengis.netspecSWE2.0reqcorenumerical-rep-valid
Req 4. A continuous numerical representation shall at least consist of a decimal
number and the scale or unit used to express this number.
The “Quantity” data type detailed in clause 7.2.8 is used to define a data component with a decimal representation and a unit of measure.
Copyright © 2011 Open Geospatial Consortium
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OGC 08-094r1 SWE Common Data Model
6.2.4 Countable discrete
Discrete countable properties are also of interest and are most accurately captured with a numerical integer representation. They do not require a unit since the unit is always the
unit of count i.e. the person if we are counting persons, the pixel if we are counting pixels, etc. Note that continuous properties can also be represented as integers with
certain combinations of scale and precision. This case should not be confused with the countable properties described here.
Examples
Array indices and sizes are countable properties with no unit. There are numerous other countable properties such as number of persons, number of bytes, number of frames, etc.
for which the unit is obvious from the definition of the property itself.
A discrete countable representation should not be confused with a continuous numerical representation whose scale and precision allow encoding the property value as an integer.
Requirement
http:www.opengis.netspecSWE2.0reqcorecountable-rep-valid
Req 5. A countable representation shall at least consist of an integer number.
The “Count” data type detailed in clause 7.2.7 is used to define a data component with an integer representation and no unit of measure.
6.2.5 Textual
A textual representation is useful for providing human readable data, expressed in natural language, as well as various alpha numeric tokens that cannot be assigned to well-defined
categories.
Examples
Comments or notes written by humans ex: data annotations, quality assessments. Machine generated messages for which there is no taxonomy ex: automatic alert messages.
Alphanumeric identifier schemes leading to a large number of possibilities that cannot be explicitly enumerated ex: UUID, ISBN code, URN.
Requirement
http:www.opengis.netspecSWE2.0reqcoretextual-rep-valid
Req 6. A textual representation shall at least consist of a character string.
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Copyright © 2011 Open Geospatial Consortium
