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Old 13-06-2011, 12:00   #1
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Chart Rotation Glitch

Hi everyone, nice forum. Of course, I have a issue.

RNC Chart 18447 (Lake Washington, WA) loads 90 degrees counter-clockwise for me. Additionally, the mouse "drag" direction moves the map 90 degrees from the direction I'm trying to move it.

Is there something I can do to get this chart turned the right way? (Downloaded from NOAA)

This doesn't happen with any other charts that I've noticed.

Thanks in advance.

Edit: Here's a screen snapshot

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Old 13-06-2011, 12:42   #2
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Re: Chart rotation glitch

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Old 13-06-2011, 13:55   #3
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Re: Chart rotation glitch

There is a technical error in the chart 18447_3-kap file.. It is rotated 270 degrees but the information in the file says that it's not skewed.
Changing SK from 0.0 to SK=270.0000000 puts the chart right but then it will not quilt. Complain to NOAA.

Thomas
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Old 13-06-2011, 14:31   #4
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Re: Chart rotation glitch

Quote:
Originally Posted by cagney View Post
There is a technical error in the chart 18447_3-kap file.. It is rotated 270 degrees but the information in the file says that it's not skewed.
Changing SK from 0.0 to SK=270.0000000 puts the chart right but then it will not quilt. Complain to NOAA.

Thomas
Hello, is there a real need for OCPN to care about SK value? Maybe it should be ignored and just recalculated by the OCPN georef algo...

Ciao, Marco.
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Old 13-06-2011, 14:39   #5
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Re: Chart rotation glitch

Quote:
Originally Posted by cagney View Post
There is a technical error in the chart 18447_3-kap file.. It is rotated 270 degrees but the information in the file says that it's not skewed.
Changing SK from 0.0 to SK=270.0000000 puts the chart right but then it will not quilt. Complain to NOAA.

Thomas
Thanks. I'll see about notifying NOAA of the error.

Ok, I submitted the problem to NOAA. Report # 16872 Included a screenshot.

Thanks Guys!
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Old 13-06-2011, 15:24   #6
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Re: Chart rotation glitch

Marco,

Sure it could be done that way. Is it worth doing.....? Well maybe it is as you can't trust it!!

Instead of waiting for Noaa, this could be corrected manually. The tools are all over this forum in different threads about chart conversion, and in the opencpn.org wiki.

The work flow would be something like this: Extract the picture from the .kap with "imgkap" or "bsb2tif", rotate the picture with "convert"(for example) and then make a new kap using the original header info, a bit reshuffled. The final size could be cut down quite a bit by cropping the picture and doing a new geo-referencing.
Assuming that the original is a proper Mercator chart, the re-worked chart would then quilt seamlessly with other charts.

Thomas
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Old 14-06-2011, 12:55   #7
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Re: Chart rotation glitch

Just received an e-mail back from NOAA:

"OCS response: The correction has been made and the chart dataset will be posted later today. Thank you."

Thanks bunches, guys.
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Old 14-06-2011, 15:02   #8
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Re: Chart rotation glitch

jafa....

Wow.... That's fast! I'm impressed.

Tax dollars at work

Dave
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Old 16-06-2011, 11:30   #9
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Re: Chart Rotation Glitch

Noaa just changed the SK value to 270. The chart is still skewed and will not quilt. To bad Noaa did not rotate the picture and kept SK=0.0.
Then we would have had something like this:
Click image for larger version

Name:	noaa.png
Views:	86
Size:	371.1 KB
ID:	28599

Thomas
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Old 22-06-2011, 08:52   #10
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Re: Chart Rotation Glitch

So I replied to NOAA that the chart doesn't quilt properly by just changing the skew, and they replied:

"Checked with mobile app EarthNC to verify that chart is correctly oriented and properly quilts."

So does that mean that as long as it works in EarthNC they consider it correct?

It's kind of frustrating as I don't have enough familiarity with this toolchain to fix this my self, or explain it to them. Any help would be appreciated.

Jafa
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Old 22-06-2011, 09:34   #11
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Re: Chart Rotation Glitch

Ok, I've done some further checking on this. It appears right now that only KAP charts with a skew of 0.0000 will quilt properly in OpenCPN.

The same problem exists, for instance, in the "Baffin Bay", "Alazan Bay" charts just south of Corpus Christi on the Gulf of Mexico.

So is NOAA making the assumption that just changing the skew factor should be sufficient to make all this work?

jafa
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