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Old 30-01-2013, 05:39   #1
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GE2KAP: very small-scale chart creation issue

I have been trying to create .kap charts to use with OpenCpn from NOAA's weather faxes (e.g. Atlantic area) using GE2KAP.
Those NOAA charts use a Mercator projection
(re http://www.opc.ncep.noaa.gov/UsersGuide/UG.pdf )
To make it easier, I crop the .tif files to 60/20° N latitude and 0/90°W longitude and save them as .jpg.
Using the following .txt file, I can generate the .kap charts with GE2KAP, but they seem off in latitude by a fair amount (about 2°, see pics)
Am I overlooking something ?
----
North=+60.0000000
South=+20.0000000
West=-090.0000000
East=+000.0000000
-----
Here is the header for such a .kap chart
=========
BSB/NA=WF48-2
NU=WF48-2,RA=1415,867,DU=0
KNP/SC=22753450,GD=WGS84,PR=Mercator,PP=0
PI=UNKNOWN,SP=UNKNOWN,SK=0.0,TA=90.0
UN=Unknown,SD=
DX=7067.70,DY=5126.64
OST/1
REF/1,235,144,53.35640,-75.05300
REF/2,235,288,46.71280,-75.05300
REF/3,235,432,40.06920,-75.05300
REF/4,235,576,33.42561,-75.05300
REF/5,235,720,26.78201,-75.05300
REF/6,470,144,53.35640,-60.10601
REF/7,470,288,46.71280,-60.10601
REF/8,470,432,40.06920,-60.10601
REF/9,470,576,33.42561,-60.10601
REF/10,470,720,26.78201,-60.10601
REF/11,705,144,53.35640,-45.15901
REF/12,705,288,46.71280,-45.15901
REF/13,705,432,40.06920,-45.15901
REF/14,705,576,33.42561,-45.15901
REF/15,705,720,26.78201,-45.15901
REF/16,940,144,53.35640,-30.21201
REF/17,940,288,46.71280,-30.21201
REF/18,940,432,40.06920,-30.21201
REF/19,940,576,33.42561,-30.21201
REF/20,940,720,26.78201,-30.21201
REF/21,1175,144,53.35640,-15.26502
REF/22,1175,288,46.71280,-15.26502
REF/23,1175,432,40.06920,-15.26502
REF/24,1175,576,33.42561,-15.26502
REF/25,1175,720,26.78201,-15.26502
PLY/1,60.0000000,-90.0000000
PLY/2,20.0000000,-90.0000000
PLY/3,20.0000000,0.0000000
PLY/4,60.0000000,0.0000000
DTM/0,0
CED/SE=2013,RE=01,ED=01/30/2013
==============












PS I know Nohal had those charts on his web site, but I can't find them right now.
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Old 30-01-2013, 06:20   #2
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Re: GE2KAP: very small-scale chart creation issue

Quote:
Originally Posted by sailorF54 View Post
PS I know Nohal had those charts on his web site, but I can't find them right now.
Yes
But http://opencpn.xtr.cz/ seems out...
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Old 31-01-2013, 15:22   #3
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Re: GE2KAP: very small-scale chart creation issue

Francois...
I'm currently in a new job on a different continent and out of servers I could misuse for these services Will try to find some new sponsor for the automatic weather chart calibration at some point.

This is more a task for imgkap or tif2bsb and Imagemagick. Anyway, at this scale and with these charts it's hard to get accurate calibration, although as far as I remember with my scripts the error was a bit smaller...

Pavel
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Old 01-02-2013, 00:11   #4
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Re: GE2KAP: very small-scale chart creation issue

Quote:
Originally Posted by nohal View Post
Francois...
I'm currently in a new job on a different continent and out of servers I could misuse for these services Will try to find some new sponsor for the automatic weather chart calibration at some point.

This is more a task for imgkap or tif2bsb and Imagemagick. Anyway, at this scale and with these charts it's hard to get accurate calibration, although as far as I remember with my scripts the error was a bit smaller...

Pavel
Thanks Pavel

I had a look at your script, and tried to paste the values in it in the kap header, but got an error when O loaded the chart.
Best of luck with your new job (hope it is not too far from the sea)
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Old 01-02-2013, 10:14   #5
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Re: GE2KAP: very small-scale chart creation issue

Quote:
Originally Posted by sailorF54 View Post
Thanks Pavel

I had a look at your script, and tried to paste the values in it in the kap header, but got an error when O loaded the chart.
Best of luck with your new job (hope it is not too far from the sea)
F
I updated the script a couple of years ago, to use imgkap and a bit better organization. No magic, but it requires a computer that can run a shell script, as it is now. For someone handy in Win scripting there can't be much in a conversion.
If you play with the kap headers you have to realize that it's calibrated against a downloaded picture directly from noaa.

Try this pic http://www.opc.ncep.noaa.gov/shtml/ppam50bw.gif
with the following header

VER/2.0
BSB/NA=OPC 96 h
NU=OPC,RA=1728,1106,DU=72
KNP/SC=18000000,GD=WGS84,PR=MERCATOR
PP=0.0,PI=UNKNOWN,SP=UNKNOWN,SK=0.0
UN=,SD=MSL,DX=000,DY=000
CED/SE=,RE=,ED=
OST/1
REF/1,128,1006,20.0,-90.0
REF/2,128,136,60.0,-90.0
REF/3,1552,136,60.0,0.0
REF/4,1552,1006,20.0,0.0
PLY/1,14.0,-98.0
PLY/2,64.0,-98.0
PLY/3,64.0,10.0
PLY/4,14.0,10.0
DTM/0.00,0.00


Thomas
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Old 01-02-2013, 12:23   #6
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Re: GE2KAP: very small-scale chart creation issue

Thanks Thomas for your input.
To use GE2Kap I still to convert the .gif pic to a .jpg pic. I can display the .kap image with O, with a rather large lt shift . Just pasting your header results in an error.
I guess I'd better wait until Paul gets back from his cruise.
Thanks again...
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Old 02-02-2013, 19:24   #7
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Re: GE2KAP: very small-scale chart creation issue

Hi all..

My new PCīs been back to the manufacturers for a couple of months for repairs.
Yes,things take a while here in the Ubatubian jungle.. he he

As you know,Paul is away on his holiday cruise in the Caribbean. He asked me to test and confirm that the present GE2KAP is working well with the latest OCPN version, which I can confirm. At least the most basic functions,the rest I will test out next week. Someone was mentioning he couldīnt get it to work with v 3.1.1328 but did not submit any details.

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Old 31-03-2013, 14:39   #8
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Re: GE2KAP: very small-scale chart creation issue

sailorF54,

I'm back and just getting around to your question.

GE2KAP does not work well with very small scale charts probably because of the distortion caused by the Mercator projection. It can't make a flat chart when there is so much difference from one edge of the chart to another.
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Old 01-04-2013, 05:11   #9
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Re: GE2KAP: very small-scale chart creation issue

sailorF54

Have you tried NoniMap Viewer? You can create large map areas and read the four
corner geo locs from the top of the screen.

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Old 02-04-2013, 08:43   #10
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Re: GE2KAP: very small-scale chart creation issue

I decided to pursue this further.



I converted the original gif to a png then calibrated it with MapCal used Mercator projection and put in 10 calibration points. I created the chart with GE2KAP but overlayed it on GE and adjusted the position of the overlay to match the GE display. it came out not bad except it dropped the top and bottom but got most of the Atlantic.

Attached are the original gif and a screenshot of it on OpenCPN
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