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Old 10-04-2015, 19:07   #1
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Long tracks lots of waypoints

I and everybody I know that has tried to use OpenCPN on long trips all complain of the slow performance of O once your track gets a few hundred miles long and you have several dozen waypoints etc..

It is particularly slow when importing tracks from GPX files (often done in areas where there are poor charts as exchanging tracks is one way that sailors can exchange accurate information). This is true even when the tracks have been cleaned and filtered to reduce the number of points. Using the track shrinking features in OCPN works, but only up to a point.

I usually resort to Oziexplorer when I have to deal with large tracks where I can filter them and clean them up. Ozi seems to be the only choice when it comes to large track files.

Maxsea handles tracks well but in a proprietary format.
To share a track I export from Maxsea, import to Ozi to filter and then export as GPX again - I can, usually, get OCPN to import this track file OK.

I know that in theory I can join track segments, and filter in OCPN but in reality it bogs.

What do other forum members do in this situation? We are talking about coastal track lengths of over 500 miles or so I guess.

I've tried various utilities such as GPSU but they all fail with the kind of tracks that cruisers rack up.

Chris
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Old 10-04-2015, 19:37   #2
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Re: Long tracks lots of waypoints

Littlechay, try "G7toWin" If you have Windows or Wine, Runs portably, no nags at least in the one I am using (1.0.etc)

G7ToWin

Look under Menu/Waypoints/Var100meters...or might be configurable-it'll reduce wpts based on proximity. and also remove duplicates

added: I see I have a "note-to-self" in the g7toWin folder:
"First, list the tracks or routes, then, you must select one,either a track or route, then right click and choose...."

that is to say, more options than the menu bar offers appear on a right-click...particularly pertinent to joining tracks .
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Old 10-04-2015, 21:31   #3
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Re: Long tracks lots of waypoints

Chris...

Can we see some actual numbers?

How many points are in a track that seems slow?
1. How many points?
2. How many seconds to import/startup?

Are we speaking of importing tracks, or of OCPN startup/shutdown performance?

Thanks
Dave
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Old 10-04-2015, 22:27   #4
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Re: Long tracks lots of waypoints

Dave,

45,000 track points (ish) 2200 odd miles after filtering.

It's not the start up times that are bad it's using the route/track control that really bogs lots of minutes to do something like delete a track for example.

When large tracks are loaded general performance issues particularly in panning the chart.

Attempting to import my latest track at the moment but will have to switch off and go to bed soon. If it works I'll send you the track but it is about 5MB

Not sure when I'll have the bandwidth to do that though.

Chris
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Old 11-04-2015, 10:43   #5
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Re: Long tracks lots of waypoints

Dave here are some numbers.

OPs please don't bash me for using MaxSea I was using it before O got to where it is now and have a large investment in Jeppersen C-Map charts that are superb. O is now getting very useful and I am finding it more reliable. I have an O-charts license and tried a few charts and will go down that route when my Jeppersen charts become outdated or I move out of the range of coverage that I have.

Timings with approx 75 track sections imported from MaxSea of between 500 miles 0.1 miles in length

Reduce track (step 10) of 46.95 miles - 10 minutes

Merge two, reduced, tracks of 30 & 46 miles - 10 seconds

Reduce track (step 10) of 60 miles - 14 minutes

Merge two, reduced, tracks, 60 & 76 miles - 10 seconds

Merge two, un-reduced, tracks 46 & 38 miles - 1 hour (more or less)

merge three reduced tracks 137, 37, .3 miles - 10 mins +

The total size of the GPX file is about 80M as exported from MaxSea, it imports quite quickly to O, but processing it to reduce the track points and merge the daily tracks is, as you can see, very time consuming. Performace improves as the tracks are compressed and merged so that there are less track sections.

Chris
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Old 11-04-2015, 11:10   #6
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Re: Long tracks lots of waypoints

Quote:
Originally Posted by HappySeagull View Post
Littlechay, try "G7toWin" If you have Windows or Wine, Runs portably, no nags at least in the one I am using (1.0.etc)
Thanks. I'll have a look. I have downloaded it but can't make it do anything useful without it doing very strange things to my data yet.

Chris
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Old 11-04-2015, 20:44   #7
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Re: Long tracks lots of waypoints

ah, here is something easier ....GPX Editor

GPX Editor | SourceForge.net

It won't exactly merge tracks as you may mean it- that is segments remain segments if there is a break in the track But it has interesting filters that reduce wpts and more.... without altering the look of the track.
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Old 14-04-2015, 10:32   #8
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Re: Long tracks lots of waypoints

GPX editor throws up an insufficient memory error. Guess it just doesn't allocate much.

Well I can get what I need done slowly in either Ozi or OCPN so no big deal. I have time on ocean passages after all


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Old 14-04-2015, 19:31   #9
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Re: Long tracks lots of waypoints

...often the long way is the best way-that's what I tell myself anyways...
BUT can't have you sailing off without one more:
"Notepad++" It can edit the gpx directly as text- nobigdeal but there's a "Macro" function where you record what you do and it will REPEAT everything you did in other files including saving them...ie: for instance, I can edit the headers of 100's of kaps in an hour or so...(I won't describe exactly how I did it because I forgot! but I saved the macro) but I do know I used that macro..also the "search and replace" inside the macro recording...

for a gpx, for instance if I had an icon that needed replacing....Macro recording on then "Search for and replace" <sym>Flag, Green</sym> with ,<sym>Flag, Red</sym> and let her roll on a bunch of files...takes a bit of practise because it will repeat mistakes too, so get the routine down first before recording.

Notepad++ Home
There's a portable version in zip or 7z on the download page

also, Check the plugins page in case there's something looking useful there.
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Old 18-04-2015, 19:24   #10
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Re: Long tracks lots of waypoints

I recently optimized the opengl rendering of tracks considerably (didn't push changes yet) which would help with rendering but not importing. I also considered that when zoomed out, we should implement a decimation algorithm to have reduced detail for tracks because otherwise it is rendering lots of line segments that are only 1 or two pixels

With that said... can you post the file with the tracks that is too slow?
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Old 19-04-2015, 12:30   #11
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Re: Long tracks lots of waypoints

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Originally Posted by boat_alexandra View Post

With that said... can you post the file with the tracks that is too slow?
It's a bit big to just post but maybe I can send another way or via email - it would be about 80MB.

Chris
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Old 19-04-2015, 14:00   #12
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Re: Long tracks lots of waypoints

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Originally Posted by Littlechay View Post
It's a bit big to just post but maybe I can send another way or via email - it would be about 80MB.

Chris
Chris...
You can ZIP it and place it on Dropbox, Google Drive or some similar service...

Pavel
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Old 19-04-2015, 14:38   #13
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Re: Long tracks lots of waypoints

OK got some time and some working internet. Here is the file zipped just remove the last extension, the smaller file is the output of speccy from on my nav computer so that you can see the specs.

About half the track, one long segment was previously cleaned up in Oziexplorer and re-imported to Maxsea, the rest is as MaxSea exports.

Chris

Edit : OK that didn't work. Thought I could upload by renaming it as a video file but this forum checks for valid files. Don't have any file sharing accounts, they are not much use to me - will set one up and revert

OK try this - link
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