Difference between revisions of "Winds Tab"

Revision as of 07:08, 6 October 2014 (view source) Mclean (talk | contribs) (→‎Polars Database) ← Older edit		Revision as of 07:22, 6 October 2014 (view source) Mclean (talk | contribs) (→‎Wind Interpolation) Newer edit →
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	[[File:CPWindInterpolation.gif|right]]		[[File:CPWindInterpolation.gif|right]]
		+	Wind interpolation is another difference between VR and VORG games.
		+	Virtual Regatta wind speed and direction are constant in each position rectangle (i.e. 1x1 degree of lat/lon).
		+	VORG game uses bi-linear interpolation, so wind speed and direction change constantly as the boat moves.
		+	Both games use constant winds with respect to time (each 12 hour periods).
		+
		+	VRTool wind interpolation can be controlled by configuring the '''Wind interpolation'''
		+	panel as follows:
		+
		+	[[File:VRLogo.gif]]  Uncheck the '''[ ]Use Wind cube''' checkbox (no interpolation needed)<br>
		+
		+
		+	[[File:VORGLogo.gif]] Check the '''[x]Use Wind cube''' checkbox<br>
		+	Select interpolation in '''time=previous''' and '''position=bilinear'''
		+
		+	[[File:ConfigWindCube.gif]]<br>
		+	''VORG configuration''
		+
		+
		+	In a '''real world''' situation check the '''[x]Use Wind cube''' checkbox<br>
		+	Select interpolation in '''time=linear''' and '''position=bicubic'''
		+	In this case, wind changes constantly with both position and time (as it does in nature).
		+
		+	A virtual regatta like that would be fun :)
		+
		+
		+	[[file:InterpTypes.jpg‎]]<br>
		+	''Interpolation methods''

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Revision as of 07:22, 6 October 2014

The following control panels are on the Winds tab:

Winds

The controls on this panel manage the appearance of the winds on the chart. There is nothing here that affects routing or track calculations, so you can safely experiment as you like to find out what each control does. The example settings shown here will give you a simple display of wind speed and direction with minimum clutter.

If you set the Wind arrow in scale control to [1] the length of each wind arrow will be the distance you will travel in one hour.

The two Wind filters options allow you to show or hide wind data according to how strong the wind is. If you set the show tws >= to say [5] then all the winds less then 5 knots will be blanked out on the chart. This is useful for highlighting holes in the wind that you need to avoid.

The wind values shown on the chart are those taken from the Grib files at the 1° Lat and Long ordinates. Remember that if you have Wind Interpolation turned on the wind speed and direction will vary between these 1° points. You can see this as you move the Ruler , Route , and Track tools over the chart.

Wind Grids

This control panel is where the weather used by VRTool is managed. There is a lot going on in this panel!

When you download weather from any of the sources, the downloaded weather is contained in a weather "grid" and is added to list of grids in the window. The grids are automatically named - the name usually (but not always) identifies the area covered, a time-stamp and where it came from.

If you tick the overwrite previous wind grid box, a subsequent download for the same area and from the same source and will overwrite an existing grid. This means that when you repeat a download for a later forecast period an existing grid will be overwritten. On the other hand, if you alter the area boundaries of a download there will be no matching grid to overwrite.

This can get quite confusing and you can easily end up with active grids that overlap. If you find that the wind on the chart is different to the game the most likely cause is that you have multiple grids active for the location. As a general rule you should:

• Keep the overwrite previous wind grid box ticked.
• Do all your downloads from a single source.
• Avoid overlapping grids.

Polars Database

Regatta Settings

Wind Interpolation

Wind interpolation is another difference between VR and VORG games. Virtual Regatta wind speed and direction are constant in each position rectangle (i.e. 1x1 degree of lat/lon). VORG game uses bi-linear interpolation, so wind speed and direction change constantly as the boat moves. Both games use constant winds with respect to time (each 12 hour periods).

VRTool wind interpolation can be controlled by configuring the Wind interpolation panel as follows:

Uncheck the [ ]Use Wind cube checkbox (no interpolation needed)

Check the [x]Use Wind cube checkbox
Select interpolation in time=previous and position=bilinear

VORG configuration

In a real world situation check the [x]Use Wind cube checkbox
Select interpolation in time=linear and position=bicubic In this case, wind changes constantly with both position and time (as it does in nature).

A virtual regatta like that would be fun :)

Interpolation methods