Can't get rid of Polar Failed Error

[rgleason]

The third configuration just completed.

Stelian, you now rate as one of the many programming wizards in this wise lot. IMHO

[rgleason]

This just completed too.
The yellow routing is the optimized route (track) to the cursor location.

[rgleason]

The next 4 CapeCanaveral complete for me.
I just attach the fourth one of the Cape Canaveral series.

[rgleason]

The 5th CapeCanaveral Configuration fails. This is an example. Why did it fail?
It says "Polar Failed".

Zoom in to the finish and find the finish waypoint. See the route and the "Time Step Interval"? It is just too big a step for the land configuration and the routing algorythm.

Solution:

Change the Time Interval to 3 hours and "Compute" again. It will complete.

[rgleason]

The next one is an almost Identical routing made by highlighting the previous route and selecting "Configuration" "New". Then a new finish point was made nearby so the route could complete with the same Time Step Interval.

When you hit Complete on the 6th Cape Canaveral configuration it completes because the location of the finish was changed slightly.

[rgleason]

The last Cape Canaveral is set up to fail with a Time Step=6hours.
For the fun of it try 1/2 hour = 30 minutes and see what happens.

See how there are small distinct tacks to sail up to the finish poiint in between the islands and land mass? This fine step is necessary sometimes to complete a routing.

At some point the algorithm will be "smart" enough to backup a couple of intervals and shorten the Time Step to 1/2 and try again. Then if not successful, back up again, shorten the time interval by another half and try again, and so on until successful. There will have to be a limit of no smaller than a 5 minute time step or it declared a Polar:failure.

When there is a polar failure, try changing the Time Interval or set a new more realistic Finish Point. Or even try adjusting max dfiverted course [Basic Tab] or if you are in high latitudes the Max Latitude [Additional Tab] but the default is 90 degrees anyway, so this is basically a constraint setting.

See this note: Weather Routing is not a subsittute for sound judgment

So Stelian,
This has been a complete success as far as I know.
Congratulations and Thank you!

[stelian]

I've installed climatology_pi and I can reproduce your results on Linux too. Everything is fine.

I'm not sure if you tested this part, but editing configurations or polars should be straightforward now: no more "unable to write" errors.

Next step: redefine the default configurations and push the changes to Sean.

[rgleason]

Great Stelian. I was going to ask about linux. I did open edit but did not actually edit polars and boat files. Will do so, and also go back to my earlier config which has the new example and review and upload and make a pr to you.

[rgleason]

Stelian, continued here
http://www.cruisersforum.com/forums/...ml#post2536929

[wholybee]

Originally Posted by rgleason

...
At some point the algorithm will be "smart" enough to backup a couple of intervals and shorten the Time Step to 1/2 and try again. Then if not successful, back up again, shorten the time interval by another half and try again, and so on until successful. There will have to be a limit of no smaller than a 5 minute time step or it declared a Polar:failure.

...

I believe that this would be one of the most important updates to make routing really work reliably. It would also allow on really long trips (like a trip to Hawaii I plan on next year) to use a long time step of 12 hours or so for fast computation, but still have the granularity needed at the start and finish.

The other update would be for the plugin to extrapolate boat speeds down to 0kts of wind if they are not in the polar. Of course it could/should display a warning about it, but with both of those changes I would think most routes would compute without fussing.

Thank you everyone, I will install and check out the new beta tonight.

[rgleason]

Wholy, how about adding that feature request to tracker wxfte,
Thanks.

[wholybee]

I have another polar failed issue that I don't understand. I'm getting pretty good overall at figuring them out.

For one route, in the middle of the pacific ocean, I get a polar failed with a timestep of 6 hours. Increasing to 8 allows the route. What could cause such a failure that increasing the time interval completes, when land is nowhere near the failure, and the wind speed is within the polar's range?

[rgleason]

You can upload your weatherroutingconfiguration.xml, polar file, grib file to here as a zip file renamed to doc or pdf. Then we can look at it, or you can post screenshots and maybe see why, but you are not going to get very far with answering that question without more information.

Probably best if you play with it and figure it out. I'd certainly like to know!