Class Name: Regular Axis

Superclass - <Axis>

Subclasses

Definition

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

Primary Page in DRM Diagram:

• 6

Secondary Pages in DRM Diagram:

Example

1. DTED is sampled in a regular grid of latitude and longitude points which is represented in a transmittal as a <Property Grid> instance. Accordingly, <Regular Axis> components are used to contain the latitude and longitude values.

2. A table of wind chill values has axes of EAC_AIR_TEMPERATURE and EAC_WIND_SPEED. EAC_AIR_TEMPERATURE values typically start at 0 degrees Celsius and are decremented in intervals of 1 degree. EAC_WIND_SPEED values start at calm (0 mph) and are incremented at intervals of 5 mph. Consequently, the EAC_AIR_TEMPERATURE and EAC_WIND_SPEED axes of the <Property Grid> instance representing this table are <Regular Axis> components.

FAQs

What is the purpose of the axis_alignment field?

The axis_alignment field provides flexibility in specifying how cells are centred with respect to middle, edge, corner, and so on.

Consider the following four (of nine possible) cases for 2D grids.

The * indicates the location where the tick mark coordinates intersect in the cell relative to the cell edges. The grid of points determined by axis tick marks represent the location of, to name a few examples, the centre, lower left corner, upper right corner, or edge, respectively, of the corresponding cell. The axis_alignment field therefore indicates the axis alignment being used.

              FACE CNTR    LR LFT CORNER   UP RT CORNER      EDGE

 Axis 1       -------        -------          ------*      -------
 ^            |     |        |     |          |     |      |     |
 |            |  *  |        |     |          |     |      *     |
 |            |     |        |     |          |     |      |     |
  --> Axis 0  -------        *------          -------      -------

Axis 0: SE_AXALGN_MEDIAN SE_AXALGN_LOWER SE_AXALGN_UPPER SE_AXALGN_LOWER
Axis 1: SE_AXALGN_MEDIAN SE_AXALGN_LOWER SE_AXALGN_UPPER SE_AXALGN_MEDIAN

Constraints

• <<Publishable Object>>
• <<General Axis Constraints>>

Component of (two-way) (inherited)

• one or more <Data Table> instances

Inherited Field Elements

Field Elements

Notes

Fields Notes

axis_type

The axis_type field specifies the property being described by the <Axis> instance.

axis_value_count

The axis_value_count specifies the number of tick marks along the <Axis> instance.

value_unit

The value_unit field specifies the unit of measurement of the <Regular Axis> instance, which 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 EDCS_AVT_INDEX), value_unit shall be set to EUC_UNITLESS.

value_scale

The value_scale field specifies the scale applicable to value_unit. If axis_type does not require a scale (e.g., if axis_type requires a value type of EDCS_AVT_INDEX), value_scale shall be set to ESC_UNI.

interpolation_type

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.

first_value

The first_value field specifies the first numeric value on the axis. When spacing_type = SE_SPACTYP_GEOMETRIC, first_value shall not be zero.

spacing

The spacing field specifies the distance between tick marks. For SE_SPACTYP_ARITHMETIC, spacing is the arithmetic difference between tick marks, such that Tick(i) = first_value + (i × spacing) where i is the i^th tick mark. For SE_SPACTYP_GEOMETRIC, spacing is the difference between tick marks such that Tick(i) = first_value × (spacingⁱ)

spacing_type

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

axis_alignment

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