Charts

[HamishB]

take care with NZ14912_1 and NZ232_2; in v27 of the NZ charts they only have palette entries 1-6, but anp.c blindly writes out 8 rules anyway, probably in the wrong place. If these charts are not fixed in the latest release let me know and I'll improve the program to deal with that.

find charts without color rule RGB/7:
$ grep -aLc '^RGB/7,[0-9]\+,[0-9]\+,[0-9]\+' *.kap

Hamish

[cagney]

HamishB

(eg if '\nRGB/' randomly appears in the binary part of the map; should probably set a 'already_did_it' variable to avoid the rules being written beyond the header)

Some months ago I patched tif2bsb to include more palettes, discussed in an earlier thread. A ruby script takes care of batch conversion. I use this snippet, to avoid writing in the binary part of a kap file.

    if line =~/\0/
      break
    end

This works, and should be possible to use in C.

Thomas

[HamishB]

Originally Posted by cagney

Some months ago I patched tif2bsb to include more palettes, discussed in an earlier thread.

yeah, I just noticed that a few minutes ago. didn't see the script, just the description that it existed.

A ruby script takes care of batch conversion. I use this snippet, to avoid writing in the binary part of a kap file.

    if line =~/\0/
      break
    end

This works, and should be possible to use in C.

i.e. if line does not contain a NULL or EOF?

anyway in the C code I'm reading/writing raw binary byte by byte, and it's not really a problem to add some `if(already_did_it) continue;` code.

do you think it's worth adding a night-red-mode palette even though OpenCPN doesn't use it? (see suggestion for NZ night-red palette from a few days ago)

I wonder... if other chart source colors are similar, perhaps imgkap could search for white-like and light-blue-like, etc color rules in the RGB palette and automatically define a dusk/night palette based on that? That way the palette matching wouldn't have to be source-specific.


Hamish

[cagney]

HamishB

That is a regular expression checking if the line contains a NULL.

I think that the conclusion last time this was discussed, was that it is not enough with a dsk and ngt palette in the chart etc. So many other things on the screen can destroy your night vision, for example, I'm just looking at the tidal dialog and most of it is not dimmed with the "Change Color Scheme" button. Not to talk about other useful programs that you need to refer to on a night watch. A general dimming of the whole screen is called for. Dave introduced this in the present beta series by hitting F6 (for Windows). For Linux I think that using "xcalib" is quite good as it takes care of all programs. More about this in the wiki..

Thomas

[HamishB]

Originally Posted by cagney

That is a regular expression checking if the line contains a NULL.

gotcha. I spend much of my time in matlab where != is ~=. Must think more SQLike.

I think that the conclusion last time this was discussed, was that it is not enough with a dsk and ngt palette in the chart etc. So many other things on the screen can destroy your night vision, for example, I'm just looking at the tidal dialog and most of it is not dimmed with the "Change Color Scheme" button. Not to talk about other useful programs that you need to refer to on a night watch.

we bop these things on the head one by one, and before you know it it's all good.
tide-level: I'm looking at it now in a latest git build -- it's got a good full xray darkeness thing going on... works for me, especially in the new full screen mode. (linux/debian sq/xfce)

it may not be enough just to have DSK and NGT, but it's a very good start!

A general dimming of the whole screen is called for. Dave introduced this in the present beta series by hitting F6 (for Windows). For Linux I think that using "xcalib" is quite good as it takes care of all programs. More about this in the wiki..

xcalib is excellent, glad to have found the tip on the wiki. My biggest complaint when running in WinXP was the brightness of the window decorations, and full screen mode will take care of that. Setting the brightness and contrast on the monitor to 0% wasn't nearly enough.

On the Mac powerbook I think it's really easy, just apple-F1/F2 or something (don't quite remember, ask a mac-head). [invert bright day mode with Ctrl-Opt-Cmd-8?]

survey says:
Really dim down an external display - Mac OS X Hints

hmmm, this one says to check out `dim` or `pmset` from the command line on OSX:
10.3: Understanding PowerBook screen dimming timing - Mac OS X Hints


best,
Hamish

[MdJ]

I make un new version to convert kap with NGT...

See http://www.cruisersforum.com/forums/...tml#post672541

Regards

[HamishB]

Originally Posted by cagney

I don't know more about gdal than you. I think that Hamish might be the man to ask.
But.....a geotiff is just a tiff with a text file. If it's just a question of a few charts just write the kap text header by hand (also called template) and use tif2bsb.
A simple script should also do, if geotiff text files are written to a standard? Compare with my script to convert ozi .map files + picture to a .kap chart. The only geotiffs I have access to are the Aussie test tiffs where one text file covers 3 charts.

Hi, sorry, just noticed this.
the `gdalinfo` program will show you the georef info.
gdal only reads bsb, it doesn't write due to patent issues in some countries.

It takes an intermediary step via GRASS to prepare a nice header, but see
https://trac.osgeo.org/grass/browser...t.kap_template

that gets you back to the geotiff, but with a properly georeferenced header template. making a bsb file from there is up to you.

n.b. gdal authors are also the same folks who look after libtiff and libgeotiff, so standards support for those is pretty good :-)


Hamish

[dacust]

Originally Posted by cagney

....a geotiff is just a tiff with a text file...

Not that it matters for this discussion, but just for information:

A tif is an image with embedded text tags "Tagged Image Format". The text part looks a lot like XML. As part of the standard, tif allows you to define your own tags.

A geo-tif just uses user-defined tags inside the tif image to store geo information. So, a geo-tif is a complete proper tif. It just has tags in it that would be ignored by a normal tif program. It MAY come with a text file, but this is usually just a world-type file with redundant information.

tif2bsb expects just a plain tif, so it ignores these user defined tags. The only way to convert it would be to pull out the user defined tags and reformat them into the header text format. OR modify tif2bsb to read it directly.

FYI: a .kap is similar to a tif in that it has embedded text as well. Just that the text is in a different format, and the image is in a tiled format for better performance when needing to only display a portion of the image.

-dan

[HamishB]

Originally Posted by GPS-Marco

Your script looks very nice but it would be great if you could write a C post-processing tool making the same (a C tool that I can compile for my poor windows O.S...).

The tool should accept as input one chart name and should convert the palette from RGB only to RGB, DAY,... I'd use it for the NZ main distribution once the best palette is agreed.

attached is an updated version which checks for presence of palette entries >6 and avoids random matches within the binary data for your consideration.

Hamish

[Rapport]

Still trying to understand kap charts. For example could anyone get the new Zealand charts to load in the Raymarine program and if not why?. They will load in Kiwitech, its precursor, once the polynomial bits were added. They load in Capcode. Imgkap ones don't load in Raymarine either.
Thanks.

[sinbad7]

Every .kap conversion I've made through MapCalII is working for me in Fugawi Marine ENC,SeaClear and OpenCPN. That is also the case with conversions made through GE2KAP and Chartconvert.

Some of the commercial companies have added protective barriers in the charts which will only run on their own platforms.

Tore

[HappySeagull]

Originally Posted by Rapport

Still trying to understand kap charts. For example could anyone get the new Zealand charts to load in the Raymarine program and if not why?. They will load in Kiwitech, its precursor, once the polynomial bits were added. They load in Capcode. Imgkap ones don't load in Raymarine either.
Thanks.

sinbad has it right,I think.For instance,my old VisNav app loads some homemade kaps but not others...What is it looking for?

I don't have a chartplotter so I'm just jabbering-shotgun help-but...

it's obvious you've compared the charts that work in your Raymarine with charts that don't?(Or,Do BSB or something else as files accompany the ones that do?-but that'd be too easy...)
Otherwise...easiest is in the header as a text.Imgkap(see the thread ) can extract these and it's really easy to try various changes to the header in notepad and rebuild.There are other apps here that can do this...That said,some of these apps add their own line of credits,so the chart is seldom an exact edit.

It might be something like the COLOUR PALETTE.Looking into the extracted image might be your best lead.Perhaps the ones you are "making" just cannot be displayed on the Raymarine.
So,there's also just looking at the compared kap charts in a hex editor and seeing if there's a clue there?If you want to get heavy,do any editing on copies( it goes without saying!)I am using a freeware editor called "HxD" that saves a backup of edits as well.You will need to change readonly property to edit copies of them...If you figure it out please post back!

[MdJ]

Originally Posted by HappySeagull

sinbad has it right,I think.For instance,my old VisNav app loads some homemade kaps but not others...What is it looking for?

If raymarine or visnav work with standard kap provided by NOAA or else, then there is no reason that this does not work with libbsb or imgkap.

The problems may come from various places, image encoding or the header.

If it's in the header, this may be version or missing parameter ...

(I'm interested to know the reasons to correct imgkap.)

M'dJ

[cagney]

Originally Posted by Rapport

Still trying to understand kap charts. For example could anyone get the new Zealand charts to load in the Raymarine program and if not why?. They will load in Kiwitech, its precursor, once the polynomial bits were added. They load in Capcode. Imgkap ones don't load in Raymarine either.
Thanks.

Which Raymarine model are you talking about? Does the documentation say that BSB2 and BSB3 are supported, or is it only BSB4?

Thomas

[HappySeagull]

Originally Posted by MdJ

If raymarine or visnav work with standard kap provided by NOAA or else, then there is no reason that this does not work with libbsb or imgkap.

The problems may come from various places, image encoding or the header.

If it's in the header, this may be version or missing parameter ...

(I'm interested to know the reasons to correct imgkap.)

M'dJ

Md'J, imgkap charts work well for me in my old Visnav.... I only test these in VisNav as a curiousity. Some charts I made differently do not work in VisNav,and it's a mystery why imgkaps do,some others don't.