User:Jcreer/Direction Conventions and Conversions: Difference between revisions

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:{| style="max-width:300px; text-align:center;"
:{| style="max-width:300px; text-align:center;"
|-
|-
!width="125px"|                  0          ||            To the east
|width="125px"|                  0          ||            To the east
|-
|                  45        ||                To the north east
|                  45        ||                To the north east
|-
|                -45        ||                To the south east
|                -45        ||                To the south east
|}
|}

Revision as of 20:13, 9 December 2021

SMS supports the following direction conventions:

Cartesian:: Add definition
Meteorologic: Add definition
Oceanographic: Add definition
Shore Normal: "TO" convention based on a Theta(grid) which defines the grid orientation relative to the positive X axis (CCW direction). So:
Theta(grid) Direction of I axis
0 East
90 North
180 West
270 South

For a shore normal grid, the direction angle is interpreted as relative to the I axis with CCW as positive. Therefore, if Theta(grid) is 0 degrees (I axis aligned with X axis) then:

0 To the east
45 To the north east
-45 To the south east

When SMS converts from one convention to another the conversions always goes through Cartesian. For example, to convert from Oceanographic to Meteorologic, SMS converts from Oceanographic to Cartesian, and then from Cartesian to Meteorologic.

The conversions that are:

Cartesian = 90 - Oceanographic
Cartesian = 270.0 - Meteorologic
Cartesian = ShoreNormal + GridOrientation
Meteorologic = 270.0 - Cartesian (add or subtract 360 if out of range)
ShoreNormal = Cartesian - GridOrientation (add or subtract 360 if out of range)
Oceanographic = 90.0 - Cartesian (add or subtract 360 if out of range)