Property Value

The SEDRIS Data Representation Model APPENDIX A - Classes Property Value

Class Name: Property Value

Superclass - <Property>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class specifies a property of the attributed DRM object and its value in terms of

its meaning (specified using an EAC, SE_Index_Code, or SE_Variable_Code),
its unit of measurement (such as metres),
and its data storage type (such as EDCS_Integer).

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

Example

The <Property Value> instances of a representation of a lake might include the EAC_SURFACE_MATERIAL_TYPE of the lake.
Consider the man-made materials that can be found on any surface, such as cloth, carpet, asphalt, silk, metal, and natural materials, such as wood. To specify the material making up a wooden wall represented by a <Polygon> instance, the data provider represents it as depicted in Figure 6.48.

Figure 48 — <DRM Property Value> example
Consider an <Areal Feature> instance representing a surface covered with vegetation. To specify the type of vegetation, the data provider gave it a <Property Value> component with a meaning of EAC_VEGETATION_TYPE, and the value specifying the exact type of vegetation.
Consider an <Areal Feature> instance labeled as "Red Field", because the surface represented has clay soil present. To describe the soil composition at some point or for some surface, <Property Value> instances are used, so a <Property Value> instance of the appropriate attribute is attached to the <Areal Feature> instance.
Consider acoustic response (that is, changes to characteristics of objects in response to acoustic stimuli) such as the resonant frequency of a plate, response (such as echo, phase shift, absorption, diffraction), or frequency.
Consider electromagnetic emission, that is, the emission characteristics of a geometric object or feature, including the electromagnetic wavelengths, amplitudes, and directionality. Examples include
1. The thermal signature of a rock at noon is described by its electromagnetic emission.
2. The headlight of a truck.
Consider electromagnetic response (that is, changes to characteristics of objects in response to electromagnetic stimuli). Some examples of such properties include reflective and specular characteristics of a surface.
Consider hydrology (that is, an attribute describing some aspect of the flow of water at a location or on a surface). For the <Polygon> instances that represent Salmon Creek, an example hydrology property represented by <Property Value> instances is the average speed of currents in the stream bed.
<Property Value> instances can provide metrics or measurements that relate to scalar properties, such as the elevation at a particular location.