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Old 19-09-2011, 12:01   #781
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Re: Charts II: NGA - 2700 Charts

Chart 92033 is odd in opencpn. It matches the chart edges and corners fine, the lat and lng are in alignment along the W, S, and E edges, but the lng lines deviate from alignment along the N edge, worst in the middle. It seems unlikely that they could have been drawn that way, so I'm wondering if it's a bug somewhere.

Chart 82534 has a similar issue, though it's not nearly as well aligned.
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Old 19-09-2011, 14:00   #782
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Re: Charts II: NGA - 2700 Charts

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Originally Posted by recri View Post
Chart 92033 is odd in opencpn. It matches the chart edges and corners fine, the lat and lng are in alignment along the W, S, and E edges, but the lng lines deviate from alignment along the N edge, worst in the middle. It seems unlikely that they could have been drawn that way, so I'm wondering if it's a bug somewhere.

Chart 82534 has a similar issue, though it's not nearly as well aligned.
The chart is slightly warped, as is 91407, which I rechecked today.
Remember that we are dealing with scanned paper charts. Dampness and humidity, and the odd dry spell in between, could very well be the cause of this. Of course we have to keep our eyes open for the possibility of a real bug in our processing, but I'm not convinced ......yet!

Thomas
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Old 20-09-2011, 15:10   #783
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Re: Charts II: NGA - 2700 Charts

Chart 71311 on the ftp server is corrupt.

I've tried to get it again from noaa, but failed. It just hangs.

Would somebody else like to try please? I used the dezoomify2.py script, so perhaps worth trying with the ruby one.


Paul
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Old 22-09-2011, 15:26   #784
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Re: Charts II: NGA - 2700 Charts

I'd like to contribute, but I'm not sure what is needed at this stage?

It would help people like me if there was a table showing the maps pending for calibration, validation, etc.
Note that the "Status for kap charts creation" table shows the map classification, rather than the status of the conversion process.


Perhaps we could also advance on the following chart types
by allowing people to contribute gpx files describing the bounding polygon for the PLYs of each chart.
The contributors would start with the gpx created automatically by the calibration process and edit it in OpenCPN or any other navigation program that displays the calibrated KAP files.

Here is an example for 56060 showing the edited gpx for the non-rectangular inset in the NW corner

The following PLYs were created from the attached gpx file:
PLY/1,31.03333333,33.16666667
PLY/2,33.08421400,33.16659000
PLY/3,33.08421400,33.80000000
PLY/4,33.74226900,34.36967000
PLY/5,34.00000000,34.36967000
PLY/6,34.00000000,35.55000000
PLY/7,31.03333333,35.55000000
Attached Thumbnails
Click image for larger version

Name:	56060_1.png
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File Type: gpx 56060_1.gpx (4.1 KB, 43 views)
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Old 22-09-2011, 16:02   #785
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Re: Charts II: NGA - 2700 Charts

NGA 2700 chart summary for Thu Sep 22 22:00:42 GMT 2011
processed: 1353 charts
evaluated: 1253 charts
pxhoriz: mean 1.00000 stddev 0.00022
>5*sd: 71140 92050 92190 92560 22531 92040 22533 29325 82534 24215
>4*sd: 83039 24311 71012
>3*sd: 71018 81427 81616 55001 93032 36005 21182 83495 82564 53091
pxverti: mean 0.99999 stddev 0.00018
>5*sd: 91407 71012 29325 83039 61003 82025 92190
>4*sd: 83105 82534 92050 83495
>3*sd: 92560 53290 56190 22533 71018 71140 24444 53287 24319 53266 43340 81796 14003 83010 18766
pxsquare: mean 0.99999 stddev 0.00019
>5*sd: 71140
>4*sd: 61003 83392 82025 92190 92560
>3*sd: 83020 29325 63361 82304 63354 81016 24215
ratio: mean 1.00510 stddev 0.00678
>5*sd: 71036 74230 75025
censored: skipped 74 charts: 11 62 70 105 106 121 124 125 126 145 301 520 521 522 524 526 532 622 623 701 707 800 21141 21161 21621 21641 22314 22404 22440 22528 22541 22542 22549 23051 23121 24511 26125 29282 29322 29324 37242 54289 54303 57022 63015 71009 73034 74024 76201 81145 81303 81329 81511 81563 81565 81576 81729 81737 81791 82384 83052 83218 83555 91020 91030 91060 91096 91314 91326 92025 92030 92033 92140 96036
notdone: skipped 1 charts: 76171
notmercator: skipped 25 charts: 14221 17421 18419 24055 28164 29323 43064 43263 43344 43363 43371 43377 43378 43386 44192 44310 54362 54364 54368 55064 56191 76181 81327 82071 91286
-----
Processed all charts with status:
+ 'Rectangular, doable'
+ 'Rectangular, partly doable - rectangular insets'
+ 'Rectangular, partly doable - non-rectangular insets'
+ 'Rectangular, not doable in Phase 1 because of special PLY's needed'
+ 'Chart done, checked and locked'
'processed' is the number of charts processed
'evaluated' is the number of processed charts that didn't get skipped
'pxhoriz' compares the lengths of the N and S edges, which should be equal
'pxverti' compares the lengths of the E and W edges, which should be equal
'pxsquare' compares the lengths of the NE-SW and NW-SE diagonals, which should be equal
'ratio' compares the aspect ratios of the REF point rectangle and the projected corner
+ coordinates, which should be equal
All those 'shoulds' are assuming a rectangular chart area in mercator projection.
'>n*sd' charts are greater than n standard deviations from the mean
'>5*sd' should be none
'>4*sd' should be none
'>3*sd' should be 3/1000 of the charts processed
All those 'shoulds' are assuming a normal distribution.
'censored' are outliers previously checked and looked 'okay',
+ there may still be a problem with data entry, or the chart may just be crooked.
'notdone' are charts with no REF points or no corner coordinates
'notmercator' are charts that aren't mercator or unknown
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Old 22-09-2011, 17:06   #786
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Re: Charts II: NGA - 2700 Charts

Recri,

24444 - I can't see anything wrong, corners, plys, gridlines, and quilting lookOK.
24511 - It has no projection but is useable by my standards
26125 and 28164 are transverse mercator, does this matter to your program?
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Old 22-09-2011, 18:30   #787
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Re: Charts II: NGA - 2700 Charts

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Originally Posted by recri View Post
NGA 2700 chart summary for Thu Sep 22 22:00:42 GMT 2011
92560 - odd datum, but otherwise all OK
92190 - datum unknown but otherwise all OK
92050 - datum unknown but otherwise all OK
92040 - datum unknown but otherwise all OK

Does the lack of datum, or lack of adjustment to WGS, explain why you are picking these up?

Paul
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Old 22-09-2011, 18:39   #788
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Re: Charts II: NGA - 2700 Charts

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Originally Posted by z.stadler View Post
I'd like to contribute, but I'm not sure what is needed at this stage?

It would help people like me if there was a table showing the maps pending for calibration, validation, etc.
Note that the "Status for kap charts creation" table shows the map classification, rather than the status of the conversion process.
etc...
z,not sure what you mean.there's 725 of charts that haven't even been looked at per that link....First stage is not complete.I just run up (or down ) the list in an area I have a passing interest in and look at every one in order,filling in whatever I can without skipping any...any info correctly filled in is a step in the right direction.The only caveats are the corner positions or the actual calibration of the corner crosshairs.I think it's best to leave these blank or reset them if they can't all be completed or it'll show up as a wound when recri runs his bot through em.
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Old 22-09-2011, 18:45   #789
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Re: Charts II: NGA - 2700 Charts

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Originally Posted by z.stadler View Post
I'd like to contribute, but I'm not sure what is needed at this stage?
There's no shortage of the basic calibration work of simple 'doable' charts.

725 charts still untouched, including the majority of those in regions 7 and 9.

Another 100+ to follow soon, when they have been deskewed.

And checking of already calibrated charts is also essential, whether by looking at recri's regular lists of potential problem charts, or using the stats pages to look for anomalies, or just picking a range of charts and going through them.

Paul
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Old 22-09-2011, 19:01   #790
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Re: Charts II: NGA - 2700 Charts

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Originally Posted by recri View Post
NGA 2700 chart summary for Thu Sep 22 22:00:42 GMT 2011
not corrected:
71018 - adjusted the corner calibrations slightly, but I doubt that will make a difference. Everything else looks OK (Mercator WGS84). Is a very small scale chart though.

71036 - Everything looks OK (Mercator WGS84). Is a tall thin chart and very small scale, if that makes a difference.

71012 - Datum correction looks correct. Another very small scale chart, and very old.

corrected:
74230 - corner coordinates corrected
75025 - corner coordinates corrected
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Old 23-09-2011, 00:42   #791
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Z.stadler

I for one is very interested in you solution for calibrating charts with obscure shapes.Can you explain more fully the process You say the calibration process creates a gpx we can use in OpenCPN that we can adjust Does the calibration process do this already or is this a wish Can you supply a step by step from jpg image to final .kap file

Regards

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Old 23-09-2011, 03:51   #792
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Re: Charts II: NGA - 2700 Charts

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Originally Posted by wdkester View Post
Recri,

24444 - I can't see anything wrong, corners, plys, gridlines, and quilting lookOK.
24511 - It has no projection but is useable by my standards
26125 and 28164 are transverse mercator, does this matter to your program?
If they were identified as transverse mercator then my program wouldn't look at them.
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Old 23-09-2011, 09:25   #793
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Re: Charts II: NGA - 2700 Charts

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Originally Posted by r.fairman View Post
Z.stadler

I for one is very interested in you solution for calibrating charts with obscure shapes.Can you explain more fully the process You say the calibration process creates a gpx we can use in OpenCPN that we can adjust Does the calibration process do this already or is this a wish Can you supply a step by step from jpg image to final .kap file

Regards

Richard
The calibration process creates a rectangular route in gpx format. I believe it is intended for use in the validation stage. The file itself is located in the directory as the resulting KAP file. I've downloaded it and modified it as a route in OpenCPN. Then I've exported the route, manually copied the lat/lon numbers from the GPX into the PLYs, and run imgkap on my PC to create the KAP shown in OpenCPN.

The suggestion is to add:
  • A manual editing step for the automatic GPX file
  • An automatic conversion of the edited GPX file into the PLY statements used for the creation of the final KAP file
IMHO, it would be best if this process is integrated into the excellent conversion server infrastructure at OpenCPN.info

Ze'ev
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Old 23-09-2011, 09:49   #794
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Re: Charts II: NGA - 2700 Charts

24055 corrected to "Mercator".so i guess that goes to show that these "non-mercator" need a double check.It's easy to "slip" on those scrolling menus when my touchpad gets staticky!
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Old 23-09-2011, 11:14   #795
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Re: Charts II: NGA - 2700 Charts

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Originally Posted by paulr View Post
92560 - odd datum, but otherwise all OK
92190 - datum unknown but otherwise all OK
92050 - datum unknown but otherwise all OK
92040 - datum unknown but otherwise all OK

Does the lack of datum, or lack of adjustment to WGS, explain why you are picking these up?

Paul
They get picked up on pxhoriz, pxverti, or pxsquare because the charts aren't as rectangular as most charts are, either they were drawn crooked to begin with or the chart paper got shrank or stretched a bit somewhere.

They get picked up on ratio because the chart isn't the same rectangle as the projected corner coordinates, the corner coordinates and the mercator projection specify an exact rectangle shape.

The datum or lack should have no effect, a purely imaginary chart could pass or fail the same tests.
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