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Old 27-07-2011, 07:34   #1
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Question Waypoints and Markers Move Relative to Chart when Scrolling ?

Hi All,

I'm new to OpenCPN, and I apologize if this "issue" is due to user error (which it very well might be).

I have tried to chart a simple route (two points) and run into a weird situation where:

1) The waypoints as identified on OpenCPN have different coordinates than if I plot them in gpsvisualizer.com (Map created by GPS Visualizer)

2) When I drop a marker or create a waypoint it moves around on the chart when I scroll the screen with my mouse. Even when I have "Lock all waypoints" set in the ToolBox. I am not using a wheel to zoom, nor do I have that box selected. (It happens when I do have that box selected, also.)

I'm using version 2.3.1 on Windows XP (2002).

Any suggestions? Am I doing something wrong?

If necessary I can provide a screen video.

Thanks for any enlightenment you can provide,

anja
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Old 27-07-2011, 08:45   #2
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Re: Waypoints and Markers Move Relative to Chart when Scrolling ?

P.S. I should mention that the chart I'm using is 14773 from here: Chart Downloader for NOAA RNCs&#153.

404 14773 View 17 9/1/2004 1 264 6/25/2011 06/28/2011 23:55:12 09 7/19/2011 7/30/2011
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Old 27-07-2011, 09:04   #3
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Re: Waypoints and Markers Move Relative to Chart when Scrolling ?

naiad...

Welcome aboard!

Can you post a screen shot or video to show the behavior you experience?

Thanks
Dave
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Old 27-07-2011, 09:50   #4
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Re: Waypoints and Markers Move Relative to Chart when Scrolling ?

‪20110727 1131 00‬‏ - YouTube

I don't know how to embed a video in the message. Didn't work in the previous message. Here's a link you can follow to view it.

Am I doing something wrong? Am I interpreting wrong what it would mean to drop a marker? I expected the marker to stay at the same place on the chart once I dropped it.
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Old 27-07-2011, 11:41   #5
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Re: Waypoints and Markers Move Relative to Chart when Scrolling ?

I think it has something to do with whether the "show skewed raster charts as north-up" is selected before a session starts.

I have noticed that if that setting is NOT checked before I start a session, everything is fine. (coordinates agree with gpsvisualizer, waypoints and markers don't slide around)

One interesting thing is that checking the box shifts the waypoint angle but not the chart underneath it.

So I think I'll be safe if I just leave that box unchecked from now on.
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Old 27-07-2011, 11:47   #6
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Re: Waypoints and Markers Move Relative to Chart when Scrolling ?

In fact, on further searching, now with "skewed raster chart" I found this thread and I suspect it's the same issue:
Route on Polyconic

In fact, they were having problems with the exact same chart! (14773)

I seem to have independently hit on the same solution (leave the "skew north up" box clear)

I'm glad it wasn't just me. Hope they update those charts soon, before more people get caught by them (and bother you guys here!)

:-o

Thanks, and let me know if you need me to test anything for you with this ^%$#@ chart. LOL
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Old 27-07-2011, 11:51   #7
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Re: Waypoints and Markers Move Relative to Chart when Scrolling ?

naiad....

Congratulations! You found a bug. Rats....

This chart is a skewed polyconic chart. Only seen in the Great Lakes, as far as I can tell.

We clearly have a problem with georeferencing on these types of charts. So many charts, so many variables.....

Anyway, the workaround is to not display these polyconic skewed charts as "north-up", but use them in their skewed (i.e. "natural") orientation.

Thanks for the report, and so sorry for the bug.

Dave
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Old 27-07-2011, 12:07   #8
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Thumbs up Re: Waypoints and Markers Move Relative to Chart when Scrolling ?

Quote:
Originally Posted by bdbcat View Post
Congratulations! You found a bug. Rats....

This chart is a skewed polyconic chart. Only seen in the Great Lakes, as far as I can tell.
Looks to me, based on the thread from March, that this is more of a chart bug than a software one. So no problem. Quit bangin' yer cranium. We need it intact to keep developing software. For charts that AREN'T buggy!


Quote:
We clearly have a problem with georeferencing on these types of charts. So many charts, so many variables.....

Anyway, the workaround is to not display these polyconic skewed charts as "north-up", but use them in their skewed (i.e. "natural") orientation.
Yep. Glad I figgered it out. (Especially since I'm planning on launching the kayak tomorrow and following my Garmin 72h to Camelot. Now at least I know where I'm supposed to be going. LOL)

Quote:
Thanks for the report, and so sorry for the bug.
No problem. Wish I'd found that earlier report so I didn't have to waste your time!

Cheers,

anja
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