Zezo forum:

Post by Le_Grand_DIC | 2016-11-17 | 20:43:25

Cvetan, does the routing acknowledges the red line below which the speed is "strongly reduced" ? I know it's not easy because the latitude varies. But as of today there is a problem because the route is very close to Saint Helene, itself close to the red line.

66 Comments

Post by Michel | 2016-11-18 | 00:38:30

May be that VR club house is out !
I never understand why VR had a largest scale on all navy event !
LiveSkipper had a better play since 2006 BWR but unknown or not top of game play knowlewdge.

Post by zezo | 2016-11-18 | 12:16:39

The reason is simple - they pay the official races to have the game linked from the official race page.

Post by LaRe-Belle | 2016-11-18 | 09:43:44

Good morning Cvetan it seems that the weather does not correspond this morning. Thank you for your work!

Post by zezo | 2016-11-18 | 12:21:35

Could be. I don't see huge differences now.

The wind is expected to differ somehow - Let's say 2-3 degrees in direction and 0.2 knots in speed.

If you see bigger difference please let me know the place where it happened.

Post by zezo | 2016-11-18 | 12:26:51

I added the penalty as it was described one year ago (decrease below 60S, zero speed at 61):

if (pos->lat <= D2R (-60))
{
if (pos->lat <= D2R (-61))
penalty = 0;
else
penalty *= (0.75 + (R2D (pos->lat) + 60) / 2);
}

Post by jacenty67 | 2016-11-18 | 13:59:54

Hi Cvetan!

On VR map it looks like we can't go below 40, not 60...
And this is not o straight line...

Post by zezo | 2016-11-18 | 14:04:54

This is for the Sodebo challenge.

For the Vendee I've just added the first 4 points of the line as ice gates. It may not be enough to keep the routing strictly above the red line, but I'll think of something when it comes to it.

Post by Anthony | 2016-11-18 | 15:50:42

bonjour pourrait on avoir l'ancien point d'arriv� de zezo juste avant la mise a jour avec les 4 points car ma route n'est plus coherente!cordialement .

Post by zezo | 2016-11-18 | 16:23:35

You should probably go with Ice 3 or Ice 4 as destination at this point of the race.

Post by WaterHammer | 2016-11-23 | 18:00:51

Hi Cvetan,
any new developments on the exclusion of the ice zone? Currently the routing dives quite deep south of it between the gate points implemented by you.
Many thanks and fair winds!
Anton

Post by finbarro | 2016-11-23 | 21:39:11

Cvetan, are you going to exclude the area of ice (ice exclusion zone) from the routing? I set my destination as "Ice 1" but the routing shows me going further south again after "Ice 1" to "Ice 2". Will this greatly reduce my speed??
Maybe you could shade the Ice Exclusion Zone and we would then know exactly where to avoid.

BTW Thanks for all the great work.

Lynfin.

Post by zezo | 2016-11-24 | 21:48:48

I will do something about it some day, but there are other issues right now.

Post by jago3813 | 2016-11-25 | 13:15:00

Hi Cvetan,

If you do not mind, I may suggest something...

First of all, I assume that the IcePoints are sorted (increasing longitude, periodicity to be managed).
Using the maximum latitude of the Ice Points - or a majoration of it, you can just let the algorithm go if the position latitude is greater than this value.
If not, then look for the IcePoint (IPk) for which the longitude is smaller than pos->long AND next IcePoint (IPk+1) has a longitude greater than pos->long. Once this is found, just check the sign of the cross-product (IPkIPk+1) with (IPkPos):

(IPk+1->long - IPk->long)*(pos->lat-IPk->lat) - (IPk+1->lat - IPk->lat)*(pos->long-IPk->long)

if it is positive, the point is in acceptable position, if not it is in the Ice Exclusion zone.

Of course, it has approximations (the earth is no planar (...)) but it should be acceptable. What is not clear to me is what could be the cost of such computation embedded in your algorithm/optimization.
What I propose is also assuming that the exclusion zone is convex. It is easy to adapt to non-convex case (which would me that the IcePoints cannot be sorted according to increasing longitude), with a bit more opertions to be performed.

Thanks for what you are doing with this tool, I really enjoy using it!

Jacques

Post by zezo | 2016-11-25 | 14:07:28

Thanks. I was thinking about the same type of solution.

For a relatively big (say > 10) number of points it could actually be faster than the static checks that I'm using now if combined with binary search of the needed data.

Post by jago3813 | 2016-11-25 | 15:13:19

Hi,

If you have any doubts/questions, or if you are facing issues with what I proposed, let me know!

Jacques

Post by jago3813 | 2016-11-25 | 17:56:04

Even quicker and more precise could be the following:
The exclusion zone latitude is a function of the longitude (there is one single exclusion latitude for any longitude value). If you can generate the exculsion latitude for let's say each 1 degree of longitude (it could be each 0.5, or whatever), then no need to locate in a sorted list the current valid interval, a direct evaluation from the longitude value will give it (integer part in case of 1 degree step). Then you just make a linear interpolation of the latitudes of the 2 bounds of your interval, and compare current position's latitude with the computed "exclusion latitude".

Jacques

Post by joebar | 2016-11-25 | 18:32:08

These are the coordinates of the ice limits as (long,lat). I measured a point every 5 degrees in longitude.

[(-180, -55), (-175, -55.5), (-170, -55.5), (-165, -55), (-160, -54), (-155, -53), (-150, -53), (-145, -53), (-140, -53), (-135, -53), (-130, -53), (-125, -53), (-120, -53.5), (-115, -54), (-110, -54.5), (-105, -55), (-100, -55.5), (-95, -56.25), (-90, -57), (-85, -58), (-80, -58.5), (-75, -58.5), (-70, -58), (-65, -57), (-60, -56), (-55, -55), (-50, -53), (-45, -51), (-40, -48), (-35, -46), (-30, -45), (-25, -44), (-20, -43), (-15, -42), (-10, -40.5), (-5, -41.25), (0, -42), (5, -42.25), (10, -42.5), (15, -42.75), (20, -43), (25, -43.5), (30, -44), (35, -44.5), (40, -45), (45, -45), (50, -45), (55, -46.5), (60, -49), (65, -50), (70, -50.5), (75, -50), (80, -50), (85, -50), (90, -49), (95, -48), (100, -47), (105, -46), (110, -46), (115, -46), (120, -46), (125, -47.83), (130, -49.67), (135, -51.5), (140, -51.5), (145, -51.5), (150, -52), (155, -52.5), (160, -53), (165, -53.5), (170, -54), (175, -54.5)]

Post by zezo | 2016-11-25 | 18:32:51

I like this approach. Come to think of it, I manage the boat polars exactly this way - preliminary interpolation down to 1
knot (with external program) and then a table lookup with a linear interpolation:

i = (int) wind;

wind1 = i;
wind2 = i+1;
v1=polar_chart[angle];
v2=polar_chart[angle][i+1];

return v1+(v2-v1)*(wind-wind1)/(wind2-wind1);

Post by jago3813 | 2016-11-25 | 19:56:35

I do not know how you got the Ice Exclusion definition. If you want to use the one given by "joebar", just append at the of the array the first value, changing its longitude to +180. Then, code could be like:

int step = 5; // Depends on the definition you have

int index = ((int)(pos->long + 180.))/5;

double lat1 = exclusion_lat[index];
double lat2 = exclusion_lat[index+1];
double long1 = -180. + index*step;

return lat1 + (lat2 - lat1)*(pos->long - long1)/step;

I am not so sure about what the cast to (int) is doing, but it should be correct as we will aply on positive values.

jacques

Post by flyman44 | 2016-11-27 | 23:42:03

Post by flyman44 | 2016-11-27 | 23:50:15

Hi Cvetan. May be stupid approach but why not modify directly yhe wind map by a standart oparation from layout. for each wind map 'AND' 0 or 1 from layout? No need to change routine then..
Just need to create the new wind map with exclusion zone..

1111111
1111111
1111111
1011110
0000100
0000000

0 is the exclusion zone.
Flyman44
PS. Many thanks for all of your work..;) So grateful..

Post by zezo | 2017-12-07 | 21:18:13

Closing the inadvarent italic tag.

Post by guigui | 2016-11-25 | 17:35:19

A way to do it would be to add a landmass south of the line, like a new continent.
More drawing, less math. It's not a very "elegant" solution but it would make the job.

That's what I did for VRTOOL. VRTOOL uses a black and white BMP image for collision detection. I modified the BMP file with a black continent south of the line.
I used a crude BMP because my computer can't handle the big original file, but hey, it works. I just have to look for the small islands...

Post by jago3813 | 2016-11-26 | 09:25:06

Hi Cvetan,

the gap between IcePoint2 and IcePoint3 is really too big (I am not far from IP2 now): is it possible to add intermediate points if you do not implement what is proposed?
Many thanks,

Jacques

Post by Sachafenestraz | 2016-11-26 | 09:37:17

Hi Cvetan,
I have a problem, when i configurate the boat the zezo is letting me pass under the Exclusion line.. like picture below https://www.sendspace.com/file/lwvzes.
Thank you!
Sacha Fenestraz

Post by THOR250 | 2016-11-26 | 13:33:10

Hi Cvetan,

Nous avons un probl�me, la route propos� va dans la zone d'exclusion, comment peut on faire ?

merci d'avance pour la r�ponse

Je vous adresse toutes mes f�licitations pour votre travail , c'est super, g�nial, vous �tes formidable

good weekend

Franck

Post by laurent-r | 2016-11-28 | 08:38:11

Weldone Cvetan .
Ice Exclusion is here, great job, thank you !
Laurent

Post by petole | 2016-11-28 | 08:53:59

Thank You Cvetan ! You made it !!

Post by zezo | 2016-11-28 | 09:02:09

The exclusion zone is here. I have to check some details, but should work in general.

Thanks to all people who helped with suggestions and data, especially to joebar for the nice array and everything else - it saved me a lot of time.

Post by jago3813 | 2016-11-28 | 11:12:15

Hi Cvetan,

Really nice job, thanks a lot.

Jacques

Post by flyman44 | 2016-11-28 | 11:22:32

Donation Done !! .. Tks a lot..
Flyman 44

Post by flyman44 | 2016-11-28 | 11:22:34

Donation Done !! .. Tks a lot..
Flyman 44

Post by Alexblond2005 | 2016-11-28 | 20:25:59

Very nice Job. Zezo, you are the real winner of this race! And VR would have to thank you also...
Best regards
Alex

Post by Inicio | 2016-11-28 | 09:20:13

Thanks Thanks! Thanks Thanks!

Post by mathfdb | 2016-11-28 | 09:25:53

thanks a lot!

Post by THOR250 | 2016-11-28 | 10:22:46

Thanksssssssssssssssssssss :) great

Post by WaterHammer | 2016-11-28 | 10:23:48

Fantastic Cvetan! Looking really good! Many thanks for your efforts.

Post by Peperazzi | 2016-11-28 | 10:57:12

Cvetan. Merci beaucoup. J'admire vraiment votre travail. C'est formidable.

Post by flyman44 | 2016-11-28 | 11:18:05

Great Cvetan. Super nice job!!.. Works fantastic.!!.

Post by NORTHKOREAN | 2016-11-28 | 11:25:16

Excellent ZEZO, it works perfectly, I hope you'll win virtual vendee globe!!

Post by hardy2 | 2016-11-28 | 13:37:13

Merci vous �tes trop fort,Cordialement

Post by flop-13 | 2016-11-28 | 18:33:13

Thanks a lot, but I think it's not exactly the same Red line following Virtual Regatta ... currently I put some one waypoint, with your point, and in VR I was in exterior of the red line.

Thanks

Post by zezo | 2016-11-28 | 19:30:07

The red line should be pretty close, but there will be differences if you schedule a change with a fixed TWA course because the wind is slightly different. But I'm working on that too.

When sailing close to the red line your ultimate source should be the game interface.

Post by michgoapp | 2016-11-29 | 14:08:49

Bonjour,
il semble que la zone d'exclusion des glaces ne soit pas la m�me sur VR. Lorsque je me positionne � la position VR, je me retrouve sous la ligne rouge? et ne peux plus calculer d'itin�raire.
Merci pour votre travail.

Post by WaterHammer | 2016-11-29 | 15:30:01

I think the red line in the router follows the great circle path (orthodrome) between the spanning points (every 5 degrees I believe). This means that halfway the red line in the router is about 0.5 nm lower than the red line in the game, which seems to be a rhumb line (loxodrome). You can also observe this by the small kink in the line at the spanning points. Beware!

Post by zezo | 2016-11-29 | 18:00:22

It's neither - in fact it's linear interpolation between the latitudes of the 5-degree points. Should be closer to the loxodrome, but not the same.

On the other hand we have no idea what is the implementation used in the game engine.

BTW the web interface should not be trusted too much either (probably due to rounding errors of the wind direction, and maybe because of new forecasts replacing the old ones too). My boat went under the red line last night with a programmed heading change, and I have left some distance to be safe.

Post by WaterHammer | 2016-11-30 | 09:06:08

Excellent! Thank you!

Post by 92gege56 | 2016-11-29 | 18:16:46

Bonjour,
Encore bravo � Cvetan pour la rapidit� d'impl�mentation de son algorithme.
Pr�s de la ligne d'exclusion, il est d�licat de se tromper de minute de changement de bord.
Mais au fait, � quelle minute les calculs sont-ils faits dans VR?
exemple si zezo indique 17h30, le r�glage doit-il �tre fait � 27, 28 29, 30, 31 ou autre?
Merci encore pour cet outil magnifique.

Post by michgoapp | 2016-11-29 | 20:28:07

Bonsoir Cvetan, je suis actuellement sur VR positionn� en 8E37'48" et 42S09'29". Sur VR je suis au dessus de la zone d'exclusion, et sur z�ro je me retrouve bien en dessous de cette limite, le routage est alors impossible. Avez vous une explication? ou une solution?

Post by michgoapp | 2016-11-29 | 20:29:17

Pardon, sur Zezo je voulais dire sur mon post pr�c�dent!

Post by zezo | 2016-11-29 | 21:22:27

Hmm I see 8E37'48" 42S09'29" well above the ice limit here.

The red line for Longitude 8E38 is at 42S25 in both places.

Post by michgoapp | 2016-11-30 | 19:08:28

Merci beaucoup, tout fonctionne, j'ai du faire une erreur.

Post by Beaware | 2016-11-30 | 19:29:16

Thank you for the work done. Congratulations, keep it up. Donated ok :)

Post by KKAOSS | 2016-12-12 | 01:27:08

lost the exclusion zone MON DEC 12 @ 00:20 CET

Post by KKAOSS | 2016-12-12 | 01:31:59

the RED LINE is Back ? dec 12 @ 00:30 hmmmm vendee globe ice exclusion lines (zone) all good
awesome Cvetan!

Post by zezo | 2016-12-12 | 01:33:55

Working late at night.

It was only the user interface, the router knew about it.

Guess it's time to go to bed.

Post by Inicio | 2016-12-12 | 09:28:43

Thanks!

Post by Flying Dutchman | 2017-12-07 | 16:38:22

Hello Cvetan,

Just joint your site. Looks amazing. I was looking for na English forum for some time as the club house seems French only:)

Regarding the Antarctic Ice Exclusion zone can anyone tell me if this is implemented in the VR 2017-2018 too? Can't find any notifications about it in VR. Do we have to follow all the sailing instructions of the Volvo Ocean in this regard?

Thanks for your reply
Flying Dutchman

Post by zezo | 2017-12-07 | 17:15:07

There is no ice limit defined a the moment. The game interface will show a red line if they add it later (which has happened before)

Post by YourMomSA | 2017-12-07 | 21:06:29

I asked in the VR forum a week or so ago, and they confirmed there won't be an ice limit.

That doesn't mean they don't suddenly change their mind... but the question has been asked and answered... so hopefully it's a firm answer.

Post by zezo | 2017-12-07 | 21:20:48

That probably means they haven't implemented the feature server-side yet. Because the interface is capable of displaying ice limits, but then our friend nsp wold deliberately step over the line and see that it does nothing ;-)

Post by Ursus Maritimus | 2017-12-07 | 23:44:51

like my basketballcoach used to say: 'if the ref don't whistle, it's allowed ..'

Post by Flying Dutchman | 2017-12-07 | 17:28:51

Ok, thanks , will keep it in mind they might add it later.

Post by toxcct | 2017-12-07 | 18:30:20

Cvetan, I guess someone opened a "[ i ]" tag in this thread, but forgot to close it.
That breaks the page display below, and the menu on the right as well, displaying italic everywhere ^^

Post by zezo | 2017-12-07 | 18:36:22

And now you opened another ;-)

Post by zezo | 2017-12-07 | 18:36:41

It's actually part of the code above v1=polar_chart[angle] is 2-dimensional array ;-)