Drag an Entire Route

[latchodrom]

Hello everyone !
I'm a french SAR crew member.
I know that it's possible to drag a waypoint from a route...
For SAR reasons I want to drag the entire route...
Any ideas?
Thanks a lot !
Jean Paul

[yachtvalhalla]

Originally Posted by latchodrom

Hello everyone !
I'm a french SAR crew member.
I know that it's possible to drag a waypoint from a route...
For SAR reasons I want to drag the entire route...
Any ideas?
Thanks a lot !
Jean Paul

Why? Please explain the utility of moving a linked series of waypoints to another location.

[PjotrC]

Originally Posted by yachtvalhalla

Why? Please explain the utility of moving a linked series of waypoints to another location.

There is a hint in the original post. This might be a need to set up a search pattern - spiral or sweeping search, starting at a given position. Some chart plotters, and certainly ECDIS generate these routes automatically. In OpenCPN - I do not see a way to do it (other than filing a Feature Request...).

[bcn]

So that would imply to define a route with waypoints that are relative to each other instead of being a location - and defining a start point (or end point).
Scaling would be another feature of course.

Interesting

bcn

[nigel1]

That would be my take, required to plot a search pattern.
As mentioned, ECDIS has this feature with a number of built in search patterns with user definable track spacing and initial course. At work, we have another nav system which way points can be added to make a route, then the whole route can be either shifted to a parallel position, or in a certain direction and distance.
Its not something which the average cruiser would need on a chart plotter, but for SAR, a must have

[latchodrom]

Originally Posted by yachtvalhalla

Why? Please explain the utility of moving a linked series of waypoints to another location.

Hello yachtvalhalla,
It's for a search pattern. I know that I could do that manually but in rough sea... i though that it would be easier and more accurate to have a predefined pattern with all wpts and drag them to the search zone.
regards
Jean Paul

[PjotrC]

Jean-Paul,

What are your parameters?

- starting position
- direction
- type of search (expanding square, sector, track line, oil-rig type)
- left- or right- turns
- extent of area or time limit
- distance between tracks
- any more?

Interesting topic... would a stand alone application producing a GPX route for import do? Maybe such tools are already available... I've seen such programs producing printouts, but not GPX.

Piotr

[latchodrom]

hello Piotr,
I think that a grid of 10 M square with wpt each 0.5M will do the job.
according to our night vision binocular range.
If I could drop such a grid, I could make an intelligent route according to our mission and sea conditions.
Making a route with existing wpts will be easier and very accurate.
I tried to create a gpx file for that and I planned to change the wpt numbers manually but the arithmetic progression is very strange. (translation beetween degrees and decimal I suppose.)
Thanks a lot for your help
Jean paul

[HappySeagull]

...it'd be haywire but if you made an image of your grid in the ".xpm" format, you could use it as the icon for a waypoint and place that waypoint anywhere you wanted. But of course, you would have to stay at the same scale of zoom on the chart, and you'd just be hand-steering along lines.

[PjotrC]

Originally Posted by latchodrom

I think that a grid of 10 M square with wpt each 0.5M will do the job.

Jean-Paul...

Is this a step in the right direction?

If you are on Windows, then you can try:

1. Download the zipped archive from search_grid.zip - 4shared.com - online file sharing and storage - download
2. Unpack the contents into a convenient folder, say "Desktop/SAR"
3. While running OpenCPN drop a waypoint in the location where you want to center the pattern
4. Go to Route Manager->Waypoints and Export this waypoint into the SAR folder, giving the file the name "start.gpx", maybe overwriting the existing one.
5. In Windows Explorer go to this SAR folder (or make a suitable shortcut before) and run the application sar2gpx.exe. It will create the file "sar_grid.gpx" in the same folder.
6. Import this file into OpenCPN - this is your 10 mile grid with 0.5 mile resolution

There is a gotcha:

- if you import it as Temporary Layer, it will be easy to delete or hide these 441 waypoints later on, and the points will be locked from accidental change...
- if you import it as GPX file, it will be possible to use the precision assured by "Use nearby waypoint?" when creating routes...

Not a truly rock-solid solution, but more or less what you asked for. It will not work (yet) across the Date Line and very near the Poles.

I thought about indicating somehow which quadrant - relative to the center - the WPs are in by different icons (NW,NE,SE,SW). Always can be done.

If you are not on Windows, I have to learn a bit more or maybe some Python soul will help...

Piotr

[latchodrom]

WOW !
You're a King !
I will try it as soon as possible... and let you know...
I'm on Windows... So everything will be allright...
It's sounds definitely that I was dreaming about...
Our area is not near the poles... thanks God !... but in Corsica island...
I found an alternative solution that consisted in creating wpts each 0.5M all over our working area...
Guess you save me a "few" hours of job....
God bless you !
Kind regards
Jean Paul

[PjotrC]

A newer version is available from search_grid_v2.zip - 4shared.com - online file sharing and storage - download

The above description still holds, but additionally, if - instead of the starting Waypoint - the file 'start.gpx' contains a Route, then the first leg of this route specifies the rotation angle for the grid, and the first waypoint specifies the center of the pattern.

So: make a simple route in the direction of wind/drift, export it, and run the new sar2gpx.exe as before.

If a non-route waypoint is found first in 'start.gpx' - all works as before.

Enjoy,

Piotr

[PjotrC]

Latchodrom...

Below the source code for the rotated grid. I use Python 2.6 under Windows.
Pls let me know if this was of any use...

Good luck!

P.

[latchodrom]

Hello Piojtr,
Thank you for the source code.
It will be a great opportunity for me to learn Python...
If I can easely spot the line for changing the mark
sym = 'diamond'
I hardly spot the one for the range of 0.5 nautical mile..
would it be this one? :
ddlon = math.cos((abs(lat0)/90.0)*(3.141592654/2.0))
that I have to change like that...
ddlon = math.cos((abs(lat0)/90.0)*(3.141592654/4.0))
to get a 0.25 NM range?
correct ?
I have not a permanent internet connection at the moment so my reactivity is a little bit slow...
Kind regards
Jean Paul

[PjotrC]

Originally Posted by latchodrom

I hardly spot the one for the range of 0.5 nautical mile..
would it be this one? :
ddlon = math.cos((abs(lat0)/90.0)*(3.141592654/2.0))
that I have to change like that...
ddlon = math.cos((abs(lat0)/90.0)*(3.141592654/4.0))
to get a 0.25 NM range?
correct ?

Correct, good luck with Python...
I'm moored within WiFi range for some time, but I'm sure you tested it all by now.

P.