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Board » General Discussion » Weather interpolation

Posted by
Exmeromotu


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2008-12-10 15:22:17
2010-07-21 06:51:44 - Weather interpolation
Hi!

I've been doing a two boat testing program using different software routers. Obviously the software program whose weather interpolation most closely resembles SOL's weather will do a better job. Since Expedition has a weather animation feature, (once you do a route you can play it back on real time with time steps of 1 minute) it was easy to see that Expedition's weather interpolation scheme is pretty close if not equal to SOL's. Sailplanner also has that weather animation feature, if you move the slider you can see how it all plays out, albeit in 10 minute time steps. But prior experience with Sailplanner is that the weather sometimes has huge differences with SOL's weather specially in light air, and when the wind shifts quickly. Supposedly with the new weather processing upgrades at SOL, Sailplanner's weather will be more "SOL-like" :). But what about Bluewater? As part of my two boat testing program I took a route that was routed using Expedition, and exported that route into Bluewater (waypoints only). Bluewater then recalculated all route data. I was extremely surprised to see that Bluewater's weather interpolation scheme is nearly IDENTICAL to Expedition and SOL. Since Bluewater does not have a weather animation feature (well it does but it's in 3 hour time steps!!) this is harder to visualize. However, you can't argue with the printed output!! Attached is a copy of the file.

Cheers!
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Posted by
kalle


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2007-06-01 09:58:04
2010-07-21 09:05:13 - Re: Weather interpolation
Two things affect SP interpolation in comparison to SOL:

1) SP does not interpolate the "wind maps" *at all*, it will only show each "frame" of the weather file. This is intentional so that SP will never show you phenomena that is only artifacts of interpolation. Note however that the SP routing continuously interpolates the weather.

2) If the weather areas in SOL and SP doesn't exactly match, you might be dealing with different resolution of the weather.

--- Last Edited by Kalle Haglunds at 2010-07-21 09:05:50 ---
Posted by
Exmeromotu


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2008-12-10 15:22:17
2010-07-21 11:57:14 - Re: Weather interpolation
Hi Kalle!

You just confused the heck out of me now... Hehehe! Question, if SP does no weather interpolation and you only have exact grib values on a roughly 2.5 degrees x 2.5 degrees grid, how does SP "fill out" the rest of the space on the map?

I raise this question, because the first time I really noticed a big discrepancy between SOL and SP was during the Inport Quingdao Race ....

Posted by
Exmeromotu
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35
Registered at
2008-12-10 15:22:17
2009-02-09 13:33:24 - Weather Forecasts in Client vs. Sailplanner [ Edit ] [ Quote ]
Hi! During th Qingdao Inport Race I noticed some pretty big differences on the weather forecasts between sailplanner and the game. Aren't they using the same weather provider?


Posted by
Jakob Kuttenkeuler

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355
Registered at
2007-09-04 10:05:30

2009-02-09 14:01:47 - Re: Weather Forecasts in Client vs. Sailplanner [ Quote ]
Yes, they are both NOAA, GFS forecasts. However, in the game we interpolate more than we do in Sailplanner. There is the difference, especially in occasions where large changes (gradients) are present in strength/direction.

...one of the guys behind the game...

That was my question and Jakob's answer more than a year ago...

Cheers

--- Last Edited by Exmeromotu at 2010-07-21 12:00:03 ---
Posted by
kalle


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2007-06-01 09:58:04
2010-07-21 14:41:31 - Re: Weather interpolation
Sorry I should have been more clear: For the weather maps, SP does not interpolate in *time*, it does interpolate over area.

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