Charts

[Surveyor]

Originally Posted by dougwm10

MAPMEDIA RASTER CHARTS – the older version with file names ending in the extension *.map

I have a large collection of the older Mapmedia raster charts whose files end with the extension *.map and I would like to use them in OpenCPN. At this time there does not appear to be a conversion or adaptation process available that would enable them to be used. There are probably a great number of other people in a similar situation so any help in solving this problem would be appreciated by a large number of sailors

Is there anyone capable and sufficiently computer savvy who can create a patch to achieve this. There is already a patch available for these charts that works with MAXSEA its name is “mapmedia-patch.exe “written by RK but I have been unable to contact this person hence my open request for help.

If there is anyone who can reverse engineer software and / or would be able to adapt the Maxsea patch to work with OpenCPN then please contact me and I will send them the file.

This has been asked a number of times in this thread and each time there is no response. The main reason being is that what you are asking for is considered a crime. Possession of those files that you mention might also be illegal but I am not positive. That being said, I am sure it (hack) has been done already but getting that data from a public forum probably is not going to happen.

[blubaju]

Originally Posted by Surveyor

This has been asked a number of times in this thread and each time there is no response. The main reason being is that what you are asking for is considered a crime. Possession of those files that you mention might also be illegal but I am not positive. That being said, I am sure it (hack) has been done already but getting that data from a public forum probably is not going to happen.

Yes and no, this depends on the local laws of your country of residence. US industry likes to SELL you everything, same time claim that you are not allowed to do with YOUR property what you like. At least some European countries honor property and once purchased it is yours. Eg. "hacking" an iPhone or private copies of my music or video library. For my own personal use I am allowed to do this, of course, I am not allowed to sell any copies, or results of my reverse engineering, but I may sell the original if I do not keep the copies. US industry likes to sell you same stuff you purchased already over and over again. And even the worse, you pay copyright fees for an empty storage medium, but you are not allowed to make any copies. This makes much sense - for the "free" US Industry.

For the question asked, a US based forum might then be not the best choice ;-) but do not ask me, though I am very interested in openCPN and love the intuitive handling compared with my very user unfriendly Raymarine plotter, I use the plotter with its charts on a cartridge just because of the integration with a radar.

[Slowboatskipper]

If the following helps then if you copy and paste the following URL
into your web browser. (The text inside NOT with the "" marks.)

"http://heanet.dl.sourceforge.net/project/openseamap/Maps/Europe"

you'll find charts for WCI, jpr, kap, kmz, png & png.cal formats by
going to the following sub-directories and downloading them
(Do not try to use the following links as links but follow the
instructions and it'll work)

Baltic Sea/ 12-Mar-2011 04:15 -
BlackSea9/ 24-Oct-2010 15:00 -
EnglishChannel10/ 26-Oct-2010 19:20 -
France/ 07-Nov-2010 16:58 -
Greate Britain/ 07-Nov-2010 16:50 -
Hungary/ 01-Feb-2011 02:25 -
Inland Waterways/ 12-Mar-2011 04:15 -
Mediterranean Sea/ 12-Mar-2011 04:15 -
Nordsee10/ 26-Oct-2010 14:55 -
NorwaySouthCoast10/ 26-Oct-2010 17:37 -
SkagerakKattegat10/ 26-Oct-2010 17:49 - ketch yawl later.

Rgds
Slowboatskipper

[sailorF54]

Originally Posted by Slowboatskipper

you'll find charts for WCI, jpr, kap, kmz, png & png.cal formats
Slowboatskipper

Kidding or what... OpenSeaMap

[zeehag]

looks like a road map to me--i will keep my paper charts and find where i am goin gvia water thanks...LOL

[maitai]

Maybe this has been asked before, if this is the case sorry for that.

Maybe one of you knows why in certain cases (quite often in fact), gdal does not seem to be able to convert image coordinates in geographic coordinates? I had a look in the code but didn't really understand why

For instance gdalInfo does not report the coordinates of the corners in (lat,lon), in this kap file from NOAA: http://www.virtual-winds.com/maitai/14782_1.KAP

[HamishB]

Originally Posted by maitai

Maybe this has been asked before, if this is the case sorry for that.

Maybe one of you knows why in certain cases (quite often in fact), gdal does not seem to be able to convert image coordinates in geographic coordinates? I had a look in the code but didn't really understand why

For instance gdalInfo does not report the coordinates of the corners in (lat,lon), in this kap file from NOAA: http://www.virtual-winds.com/maitai/14782_1.KAP

Hi

what does the header of the NOAA .kap file look like? (open it in a text editor)

is it a coastal chart, harbor chart, great lakes / inland waterway?

I suspect the chart will be in the polyconic projection or so, not the usual merc or tmerc. search for bugs about it at http://trac.osgeo.org/gdal/tickets


Hamish

[Tupaia]

I realise that this is an old, looong thread and may have been answered or superceded but.

I have a question on georeferencing small scale charts (those covering a big area).

If the original chart already existed as a mercator chart, in whatever format, when it is converted to a .TIF (for example) why would there be a need for more than 4 reference points?

[bdbcat]

Tupaia...

Theoretically, no need for more than 3 well selected points. But I think it depends on what you are planning to do later with the TIF conversion. Just display it? Or georef into it?

More info on your use case?

Dave

[Tupaia]

Originally Posted by bdbcat

Tupaia...

Theoretically, no need for more than 3 well selected points. But I think it depends on what you are planning to do later with the TIF conversion. Just display it? Or georef into it?

More info on your use case?

Dave

I have just been playing with a few old digitised charts that I now have converted to TIF format. I was planing to convert them to KAP.

Another question I know about the color/pallet issues with TIF but was wondering about PNG, the file sizes are much smaller 780k vs 99mb. I also have the original pcx at 7.8mb Is there a direct route from pcx to kap?

[seandepagnier]

kap uses tif format.

If you want a smaller kap file, you should compress to kap.xz (possible from within opencpn)

[nohal]

Tupaia...
KAP chart is nothing else but a TIFF with 2-127 color palette and a text header describing the chart and it's calibration. Starting with a PNG, you will not get a 100x smaller chart file, neither starting from PCX you get a 12x smaller chart file than if you start with a TIFF.

To save size of the resulting chart, you have several options
- reduce the pixel size of the image (we do not know how your pictures look so can't asses whether it is an option in this very case or not)
- reduce the palette (We do not know how your pictures look, but looking at the numbers you posted, there pretty sure is a lot of room for improvement in your workflow)
- remove artifacts from the images (We don't know what your images look like, but especially for scanned images, it is often a good idea to do some tuning to the images to remove moire and make the uniform color areas really uniform color)

You don't say what tools are you trying to use, but if you do use imgkap, it takes pretty much any image format as input, even PCX, so you don't have to do any conversion yourself.

It would be a bit easier to suggest an "optimal" way to handle your chart portfolio if we could have a look at one of your PCX files...

Pavel

[Tupaia]

Thanks, I have now downloaded IMGKap.exe and the No.88 post description. This looks more straight forward so I will go through this and see how I get on.

I had some original charts copied and the copy shop gave me a DVD with the print files on it. I thought it would be interesting to convert them for use on OCPN.

I was trying to use older methods from outdated threads. It is hard to work out what is the latest approach as instructions and comments are spread about in many places.

[rgleason]

Kap Charts for OpenCPN from OpenSeaMap
KAP-charts from OpenSeaMap - OpenStreetMap Wiki

Baltic Sea 400mb
British Channel 220mb
Mediterranean Sea West 520m
Mediterranean Sea East 540mb
Adriatic Sea140mb
Gulf of Biscay 110mb
North Sea 550mb
Caribbean220mb
South Chinese Sea 200mb
East Chinese Sea 150mb
South Pacific Islands 500mb
Magellan Strait 25mb

How good are these?

[fgd3]

None of the OSM charts I've seen show any underwater features. I find that rather limiting.

Fabbian