Class Name: Regular Axis

Superclass - Axis

Definition

An Axis that uses a constant spacing between hash marks and numerical values.

Primary Page in DRM Diagram:

• 6

Secondary Pages in DRM Diagram:

• 18

Example

1. Digital Terrain Elevation Data (DTED) is sampled in a regular grid of latitude and longitude points. Accordingly, the latitude and longitude Axes resulting Data Table are Regular Axes.
2. A table of wind-chill values has axes of air temperature and wind speed. Air temperature typically starts at 0 degree Celsius and is decremented in intervals of 1 degree. Wind speed starts at calm (0 mph) and is incremented at intervals of 5 mph. Consequently, the air temperature and wind-speed axes of this table are Regular Axes.

FAQs

The introduction of the axis_alignment field allows a flexible specification of middle, edge, corner, etc centered cells. Consider the following 4 (of 9 possible) cases for 2-D grids.

The * indicates the location where the tick mark coordinates intersect in the cell relative to the cell edges. I.e.: the grid of points determined by axis tick marks represent the location of the lower left corner - or the center - or the ... of the corresponding cell. Axis alignment tells you which.

              FACE CNTR    LR LFT CORNER   UP RT CORNER      EDGE

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

 Axis 0:  SE_ALIGN_MIDDLE  SE_ALIGN_LOWER  SE_ALIGN_UPPER SE_ALIGN_LOWER
 Axis 1:  SE_ALIGN_MIDDLE  SE_ALIGN_LOWER  SE_ALIGN_UPPER SE_ALIGN_MIDDLE
 

Constraints

Component of (one-way)(inherited)

• optionally, some Property Grids
• optionally, some Property Tables

Component of (one-way)

• optionally, some Mesh Face Tables

Inherited Field Elements

Field Elements

Notes

Fields Notes

axis_type

 gives the type of measurement along the axis, such as distance,
 pressure, frequency, etc.

axis_unit

 specifies the unit of measurement of the axis_type

axis_value_count

 indicates the number of "hash marks" along the axis

interpolation_type

 allows the data supplier to indicate how best to interpolate
 the data to points that are in-between grid points on the axis.
 When a <Data Table> has more than one axis, the order of the
 interpolations is in the order of axis definitions.

first_value

 first_value is the first numeric value on the axis

spacing

 spacing is the distance between hash marks;
    the arithmetic difference for linear,
    the logarithmic difference for logarithmic.
 i.e.: counting from 0, the value for tick 'N'
    is = first_value + N * spacing (for linear), and
    is = first_value * spacing^N (for logarithmic).

values_are_ints

 SE_TRUE if the first_value and spacing fields represent integers

type_of_spacing

 type_of_spacing indicates the type of regular axis

axis_alignment

 axis_alignment indicates the position of the axis
    with respect to the axis interval. Note that
    LOWER and UPPER refer to the axis INDEX; e.g.,
    LOWER means aligned to the side with the lower index