Class

• <DRM Regular Axis>

Superclass

• <DRM Axis>

Subclass

• None.

Definition

An instance of this DRM class is an concrete instance of <DRM Axis> that uses a constant spacing between hash marks and numerical values.

The value_unit field specifies the unit of measurement of the <DRM Regular_Axis> instance that shall be compatible with the requirements imposed by axis_type.

If axis_type does not require a unit of measurement (e.g., if axis_type requires a value type of STRING), value_unit shall be set to EUC_UNITLESS.

The value_scale field specifies the scale applicable to value_unit.

If axis_type does not require a unit of measurement (fe.g., if axis_type requires a value type of STRING), value_scale shall be set to ESC_UNI.

The interpolation_type field allows the data provider to indicate how best to interpolate the data to points that are between grid points on the axis. When a <DRM Data Table> has more than one axis, the order of the interpolations is in the order of axis definition.

The first_value field specifies the first numeric value on the axis.

The spacing field specifies the distance between tick marks.

For ARITHMETIC, spacing is the arithmetic difference between tick marks, such that:

Tick(N) = first_value + (N * spacing)

For GEOMETRIC, spacing is the difference between tick marks such that:

Tick(N) = first_value × (spacing^N)

The spacing_type field specifies how the spacing value is used to compute tick marks.

The axis_alignment field specifies the position of the axis with respect to the axis interval.

NOTE  The terms “lower” and “upper” refer to the axis INDEX; e.g., “lower” means “aligned to the side with the lower index”.

Class diagram

Figure 6.262 — DRM_Regular_Axis

Constraints

• Axis type restrictions
• Publishable Object

Example(s)

• DTED is sampled in a regular grid of latitude and longitude points. Accordingly, the latitude and longitude <DRM Axis> instances resulting from <DRM Data Table> instances are <DRM Regular Axis> instances.

• A table of wind-chill values has axes of air temperature and wind speed. Air temperature typically starts at 0 degrees Celsius and is decremented in intervals of 1 degree. Wind speed starts at calm (0 kph) and is incremented at intervals of 5 kph. Consequently, the air temperature and wind-speed axes of this table are <DRM Regular Axis> instances.