Route Properties Bug (5.6.0)

[sadiiqi]

In creating a route for a distance race (out to a mark and return) I used the same waypoints for some of the outward and return legs. I noticed that the route properties was missing some of the legs.
To test I created a simple search pattern route - when I started to backtrack using the same waypoints, the bug appeared with legs corrupted.
Attached are screen shots to assist if anyone can help.
In the interim I'm having to ensure I don't use a waypoint more than once on a route, not ideal.

[bdbcat]

By "backtrack", do you mean:
a)Create another route using the same points (in reverse)
or
b)Append to the route, starting at the end, and use the existing points in reverse?


Thanks
Dave

[sadiiqi]

backtrack - b).
Am creating a route for a race - out to a distant mark, round it, and return using the same WP.

[bdbcat]

OpenCPN 5.60 does not fully support re-use of routepoints within a single route. The function was judged to be not frequently used, so not worth the extra coding and test time. Some situations work fine, others not so. One can imagine some truly pathological routes to stress the logic, but these have no real useful navigational utility value.
In practical navigation use, if you truly mean to retrace a route in reverse, the simple and quick solution is right-click->Reverse Route.


Dave

[Antipole]

I have done extensive testing of this under OCPNv5.6 on MacOS Monterey for the purposes of developing my Housekeeper script. For the creation of the routepoints themselves I have seen no issues and have been unable to fault OpenCPN on this aspect.

The issue is with the derived parameters and here OpenCPN makes mistakes. It is likely that when it needs to derive, say, bearing from 003 -> 004 and there is more than one occurrence of 003 and/or 004, it gets confused about which occurrence to use. I assume, although have not tested, that OpenCPN will navigate the route correctly. It is the derived attributes in the properties window that it gets wrong.

If you subsequently delete or remove points in such a route, you can end up with successive repeating points e.g. A -> B -> B ->A and, in this case, if you remove the Bs you can even get A -> A which is of course nonsensical. OpenCPN allows this without complaining. Housekeeper cleans these up and, in the last case, will offer to delete the nonsensical route.

[rgleason]

Maybe Opencpn should simply not allow selection of a WPT twice?

Should this be entered into tracker or issues?

[bdbcat]

Yes, for reference and collective memory.

[Antipole]

Originally Posted by rgleason

Maybe Opencpn should simply not allow selection of a WPT twice?

Should this be entered into tracker or issues?

I see several uses for a closed route.

I and others use it to mark out an area such as a firing range. Yes OCPN Draw could do this but a quick closed route can be simpler.

Others create a closed route to demark an area and export it as a GPX file for generating mbTiles of satellite images or even Navionics chart tiles (dubious use but yesterday I saw it part of a recipe somewhere on this forum).

The problem only effects the Properties window - not the use of the route - I think. Tell me if that is wrong.

So perhaps that window should include a warning that the route contains repeated use of routepoints and the derived data (bearings, ties etc.) will probably be wrong. This is not ideal but, as Rick says, it is a rare situation and probably best to leave the existing uses available. After all, if you use it to mark an area, you will not be interested in the derived data anyway.

[bdbcat]

Antipole...


As I said, some re-use of points is OK, some not.
Simple closed routes, as used to demark an area for whatever reason, work fine. Properties info seems accurate to me.


I have a hard time thinking of the practical application for other cases of point reuse.


I suppose we could write condition code to allow this one use-case (simple route closure, last point is first point), and disallow all others. Something to discuss, anyway.


Dave

[Pearson 39-II]

Originally Posted by bdbcat

OpenCPN 5.60 does not fully support re-use of routepoints within a single route. The function was judged to be not frequently used, so not worth the extra coding and test time. Some situations work fine, others not so. One can imagine some truly pathological routes to stress the logic, but these have no real useful navigational utility value.
In practical navigation use, if you truly mean to retrace a route in reverse, the simple and quick solution is right-click->Reverse Route.


Dave

Dave, consider, please, OpenCPN is used for sail racing, just as framed in the original post. Very often, unless we race in light air, the race committee specifies just before the start a race course route that is either windward-leeward or around a three-wpt triangle but nearly always specifies "twice around" or even more specs that reuse the exact same race marks - often in our region these race marks are fixed USCG Daymark ATONs.

Often in the Sailing Instructions for a regatta, the more complex race course routes are specified days before the event and we have time to enter them in OpenCPN beforehand, then choose the committee boat specified race course minutes before our start. You are right, OpenCPN handles these badly and it has been driving us crazy for several years now.

Examples: In the Summerset Regatta distance races they have always sent us around a triangle then way out to a western mark, then return east to repeat at least some of the same marks. Similar for the Golden Conch, Conquistador, and Hospice annual regattas.

Even with 5-6 crew we have to set up the race course at the Nav station before the start, Activate the route, connect OpenCPN to the networked cockpit instruments to display brg/dist to next waypoint, VMG, ETA, etc. Once started we need it to be "set and use", automatically sequencing to next race mark waypoint. No one typically has the freedom or, if free, the knowledge to drop down below deck and right-click on anything to fix the navigation, especially at a mark rounding after which we really need to know where to race to next.

This is recognized as a valid need in the OpenCPN manual under "Using Routes". Down near the end, after describing combining routes using Append, there is "Example 3.:
" Example 3:
Append a route with a waypoint that you drop onto the route itself. Click “Yes” to the append question. The route will be circular now and go round twice. Each time you click the new to append waypoint on the route itself you will append the whole route again and double the number of loops in the route. Sounds like a gimmick, but is consistent and might be used for racing tracks."

Darned if I can follow that instruction so far, but I'm working on it as that is a great "twice around" route creation shortcut for our racing. Please consider asking someone to take this on as a bug that has application needs, just as OpenCPN has recognized racing with the inclusion and support of the Tactics Plugin. Thanks.

[wholybee]

Is there a problem using multiple waypoints at the same coordinates?

[Pearson 39-II]

Warren, could you clarify your question, please? Do you mean re-using identical waypoints in a single route?

Or are you suggesting we could create two or more "separate" waypoints at the same coordinates, then find a way to include them only once in a route, avoiding the problem we have been discussing in this thread? If so, have you done this and could you describe how to do that in creating a route?

[rgleason]

@Pearson 39-11 wrote:

This is recognized as a valid need in the OpenCPN manual under "Using Routes". Down near the end, after describing combining routes using Append, there is "Example 3.:
" Example 3:
Append a route with a waypoint that you drop onto the route itself. Click “Yes” to the append question. The route will be circular now and go round twice. Each time you click the new to append waypoint on the route itself you will append the whole route again and double the number of loops in the route. Sounds like a gimmick, but is consistent and might be used for racing tracks."

Darned if I can follow that instruction so far, but I'm working on it as that is a great "twice around" route creation shortcut for our racing

I have tested this with O5.9 most recent version and it works properly. I picked every other waypoint to be shared.

Please advise exactly what you are doing to achieve a twice around as it may be useful for others (is it a bug or a feature?).


This is an old thread.
Also what don't you understand about this part of the User Manual?
https://opencpn.org/wiki/dokuwiki/do...ute_around_leg

[Antipole]

@Pearson You might also want to look at the Build race courses script for the JavaScript plugin.

This lets you build a course from a list of race marks, noting whether they should be left to port or starboard. It also has the concept of a finishing line. The is no reason you could not construct a course that goes round more than once.

It is described in the plugin User Guide, section 23F (page 66 of the pdf version).

[Pearson 39-II]

Originally Posted by rgleason

@Pearson 39-11 wrote:

I have tested this with O5.9 most recent version and it works properly. I picked every other waypoint to be shared.

Please advise exactly what you are doing to achieve a twice around as it may be useful for others (is it a bug or a feature?).


This is an old thread.
Also what don't you understand about this part of the User Manual?
https://opencpn.org/wiki/dokuwiki/do...ute_around_leg

Rgleason, the part I do not understand in example 4 of the manual is "Append a route with a waypoint that you drop onto the route itself. Click “Yes” to the append question. The route will be circular now and go round twice. "

What? If I create a route of, say 4 waypoints, almost a closed triangle, but not closed. Then I right click away from the route and select "drop mark" I cannot get that dropped mark to interact with the route, even by dragging it to the and over the route, and there never is any append question. Could you please rephrase what the writer actually means? How does one "append a route with a waypoint?

If instead I hover cursor over the route, comprised of waypoints 001-004, , right click, and choose "append waypoint" then left ciick past waypoint 001 and on the first route leg I can then get a waypoint 005 appended to the route and on route properties it shows it follows wpt 004. The route is now sort of circular, but it does not replicate wpts 001-004 to go twice around and there was never an "append question". What am I missing here, please?