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Old 12-09-2017, 10:14   #1
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KAP header from scratch

Hi all, I'm working on a small applet to create my own OpenCPN charts from scratch (scratch==point-measurements from depths). I've gone all the way and now I'm up to the stage of converting my .png files into .kap charts. This is my first time creating headers, using imgkap, libbsb etcetera.

For each .png image, I have the N,E,S,W extents in degrees and the size in pixels. Is it true I can build an entire header from just this data? I have no clue about resolution or whatsoever.

Now well, I thought it was that simple. So using python I created some of my own headers. None of them succeeded after converting it using imgkap.
Then I just put a .png into MapCal, do the manual calibration and then convert it using imgkap. Now, the .kap file can be opened in FME (another geo-software-package), but is not showing up in OpenCPN.

Without the MapCal calibration (but my own) the log says:
5:37:53 PM: Loading chart data for C:\imgkap\zeeland.kap
5:37:53 PM: ...initialization failed for C:\imgkap\zeeland.kap
5:37:53 PM: CreateChartTableEntry() failed for file: C:\imgkap\zeeland.kap

With the MapCal calibration:
6:00:15 PM: Loading chart data for C:\imgkap\zeeland.kap
6:00:15 PM: Adding chart file: C:\imgkap\zeeland.kap

So it does seem to have effect. It's just not showing up on my screen. Can somebody point me in the right direction of what I'm doing wrong, or is it just a stupid setting?

I've also attached the .kap file. (replac the .doc)
Attached Files
File Type: doc zeeland.doc (180.8 KB, 11 views)
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Old 12-09-2017, 11:37   #2
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Re: KAP header from scratch

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Originally Posted by Baksteen View Post
Hi all, I'm working on a small applet to create my own OpenCPN charts from scratch (scratch==point-measurements from depths). I've gone all the way and now I'm up to the stage of converting my .png files into .kap charts. This is my first time creating headers, using imgkap, libbsb etcetera.

For each .png image, I have the N,E,S,W extents in degrees and the size in pixels. Is it true I can build an entire header from just this data? I have no clue about resolution or whatsoever.

Now well, I thought it was that simple. So using python I created some of my own headers. None of them succeeded after converting it using imgkap.
Then I just put a .png into MapCal, do the manual calibration and then convert it using imgkap. Now, the .kap file can be opened in FME (another geo-software-package), but is not showing up in OpenCPN.

Without the MapCal calibration (but my own) the log says:
5:37:53 PM: Loading chart data for C:\imgkap\zeeland.kap
5:37:53 PM: ...initialization failed for C:\imgkap\zeeland.kap
5:37:53 PM: CreateChartTableEntry() failed for file: C:\imgkap\zeeland.kap

With the MapCal calibration:
6:00:15 PM: Loading chart data for C:\imgkap\zeeland.kap
6:00:15 PM: Adding chart file: C:\imgkap\zeeland.kap

So it does seem to have effect. It's just not showing up on my screen. Can somebody point me in the right direction of what I'm doing wrong, or is it just a stupid setting?

I've also attached the .kap file. (replac the .doc)
Your zeeland.kap file loaded and displayed okay in OpenCPN on my PC. Here is a screenshot.

Click image for larger version

Name:	zeeland.kap.png
Views:	58
Size:	292.9 KB
ID:	155955

This appears to have been created using MapCal2 and mc2bsbh and possibly KapGen.

In order to display the chart, I had to know the approximate latitude and longitude. So, I looked at the border polygon values in the header. Then, I centered my OpenCPN at that corner.

You could right click on the chart canvas in OpenCPN and select "Center View". Enter "51 42 N" for latitude and "4 27 E" for longitude. The Center View dialog box is in the screenshot. You might have to zoom in or out to see the chart. It is usually easier to find new charts if you have "Show Chart Outlines" enabled in O.

Paul
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Old 13-09-2017, 01:41   #3
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Re: KAP header from scratch

Thanks for checking Paul, but strangly it still doesn't work for me. I indeed know the location of the chart and chart outlines are also enabled (they work for others).

for now, the charts are indeed generated with the use of mc2bsbh and a manual MapCal calibration. But as soon I can see a little it of chart on my screen, I'll skip that step.

What is your openCPN version?
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Old 13-09-2017, 06:24   #4
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Re: KAP header from scratch

@Baksteen,
Here the same, good looking on O4.8.
BTW if you come to zeilersforum.nl, you find more people working on simular charts. And the communication is in dutch;-)
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Old 13-09-2017, 07:53   #5
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Re: KAP header from scratch

Thanks, after checking everything I reinstalled OpenCPN. Now they'll show up fine, strangely with use of the same versions..

@rooiedirk
I'm already on Zeilersforum Just thought there was more knowledge on openCPN and kap files over here. When the full workflow is done and results are satisfying for me, Ill definitely share it on Zeilersforum. But for now mainly the interpolation-part is a bit tricky. Give me a week!
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Old 13-09-2017, 09:27   #6
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Re: KAP header from scratch

Quote:
Originally Posted by Baksteen View Post
Thanks for checking Paul, but strangly it still doesn't work for me. I indeed know the location of the chart and chart outlines are also enabled (they work for others).

for now, the charts are indeed generated with the use of mc2bsbh and a manual MapCal calibration. But as soon I can see a little it of chart on my screen, I'll skip that step.

What is your openCPN version?
Yesterday, when I made the screenshot, I used my build of OpenCPN 4.8.0 modified by commits through 07 Sep. 2017 made by bdbcat, the lead developer.

This morning, I used the official release of OpenCPN 4.8.0 for Windows, and it displays your sample chart the same as in my screenshot.

Whenever a KAP is added to OpenCPN's Chart Directories you should have the program run the "Scan Charts and Update Database". This also should be run if you make a change to a KAP that was previously in the chart database. Also, if you use chart groups other than the default "All Active Charts" group you must make sure that the new chart is included in the chart group that you are using.

Paul
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Old 14-09-2017, 00:54   #7
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Re: KAP header from scratch

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Originally Posted by .Paul. View Post
Whenever a KAP is added to OpenCPN's Chart Directories you should have the program run the "Scan Charts and Update Database". This also should be run if you make a change to a KAP that was previously in the chart database. Also, if you use chart groups other than the default "All Active Charts" group you must make sure that the new chart is included in the chart group that you are using.
We do have computers, haven't we?
Why the software doesn't do that by itself automatically?
There is something wrong.

Gerhard
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Old 14-09-2017, 03:17   #8
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Re: KAP header from scratch

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Originally Posted by CarCode View Post
We do have computers, haven't we?
Why the software doesn't do that by itself automatically?
There is something wrong.

Gerhard
We don't all have super fast computers and we don't want the program wasting valuable time scanning for files that probably have not changed in many days. There is nothing wrong here.
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Old 14-09-2017, 03:39   #9
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Re: KAP header from scratch

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There is nothing wrong here.
Nothing a click on the "add to ignore list" button doesn't sort out
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Old 14-09-2017, 08:20   #10
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Re: KAP header from scratch

It works OK except that the colours looks a bit weird, specially for the depth area. But good job otherwise.
Bye
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Old 14-09-2017, 09:43   #11
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Re: KAP header from scratch

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We don't all have super fast computers and we don't want the program wasting valuable time scanning for files that probably have not changed in many days. There is nothing wrong here.
A modern operating system knows when a file or the content of a folder has changed. Anyway there is no support for 20 year old computers in OCPN. So this argumentation is wrong.
Changing or adding a chart file should result in a new database scan automatically. Any smart developer can code that.

Gerhard
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Old 14-09-2017, 09:53   #12
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Re: KAP header from scratch

We await your pull request with great anticipation...
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