User:Jcreer/Direction Conventions and Conversions: Difference between revisions
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|width="125px"| 0 || To the east | |||
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| 45 || To the north east | | 45 || To the north east | ||
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| -45 || To the south east | | -45 || To the south east | ||
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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)
