Charts II: NGA - 2700 Charts

[cagney]

Originally Posted by phiggins

Pavel I sent the header.

HappySeaGull,

Well that is what I did, calibrate the chart with MAPCAL with the borders and then after saved it I ran GE2KAP that created the chart form the entry in CHARTCAL.DIR. GE2KAP calls TIF2BSB internally to create the chart.

Interesting that if I added more than 9 border points, TIF2BSB only puts in the first 9. Maybe charts can only have 9 or perhaps its a bug in TIF2BSB. Have you tried more than 9?

Paul
By coincident I just converted a 12 PLY pts chart with imgkap.
To test, I tried the same conversion with tif2bsb. No problems at all.
Check your script.......
Thomas

[HappySeagull]

hmm yes,it works fine in tif2bsb too.there are 11 points or more in this.Sorry for unclear screen grab,but they are there.

[HappySeagull]

The Ply thing per harbour plans.I'm still trying to see what my ol'CHS charts do.Sometimes it seems they just duplicate the kap with new plys(as I did 3posts above ), but I still get the feeling I'm missing something ...that one kap can quilt in several places!because I don't see a lot of duplicates with same size.Is that possible?The bsbs(that OpenCPN doesn't bother with?) might be it...

no.confusion arises because a kap of several plans was published with only one calibrated.The rest have their own kaps.

[nohal]

Originally Posted by HappySeagull

The Ply thing per harbour plans.I'm still trying to see what my ol'CHS charts do.Sometimes it seems they just duplicate the kap with new plys(as I did 3posts above ), but I still get the feeling I'm missing something ...that one kap can quilt in several places!because I don't see a lot of duplicates with same size.Is that possible?The bsbs(that OpenCPN doesn't bother with?) might be it...

Happy...
They can come from the same image and define different polygon and usually also a lot of other parameters (Scale of the particular plan, more precise REF points, etc. etc. etc.) - it's just less efficient size-wise, but works without problems. Actually I will love anybody who does not crop the NGA images while doing the calibration before our "official" process is ready

The BSB can be regarded as an envelope for more KAPs coming from the same original paper chart (that's why it can be left unused and we still can display the charts - not the case with all the other systems though)
It says (among other things): From this piece of paper coming from agency XY, the author ZZ created one coastal chart and 3 harbor plans, updated them to certain NTMs and states that he does not take any responsibility if you use them.

Pavel

[HappySeagull]

Thanks,Nohal...that explains em(bsbs)...and I see that the harbour plans I have are indeed cropped copies that match the size of the harbor plan sheets exactly...
and don't worry...we're just swingin' bats on the sidelines in anticipation...

[phiggins]

HappySeagull,

Thanks, yes there was an error in my code where it wouldn't create more 9 border points.

[phiggins]

HappySeagull,

How do you convert the jpg file before you start the process to convert to a kap?

Thanks

[HappySeagull]

oh,boy.It's a recipe that is changing with the kap-making app.Image Conversion IS the hurdle,i think....

But for these NGA's,
Step one for MapCal_2 calibration,I batch convert with irfanview in it's GUI in one process.50% reduction,output= bmps.
I'm having faster opening with bmps.Big Png's stall and a crash in MapCal is EVIL.Colour reduction could be more now but even without any(because with bmps on Win, is there any point?),they generally work.

Then,Step two,getting ready for tif2bsb,I batch convert to 127 colour uncompressed tiffs with irfanview.(Yes,it's there as an option in the dialogue as "Other")..Floyd-steinberg dithering off "Uncompressed" because there's been some confusion in my head and in other forums per Packbits,LZW,FloydSteinberg..addons in general always avoided etc.

And the output kap is compressed anyways (with LZW?)with no difference in size whatever.

I've done all the same lately with GraphicsMagick in cmd line too -it has a beautifully ordered Palette compared to Irfanview but I can't see improvement in the kaps yet and I'm new to it and haven't settled on my scripts etc.Speed is the same or a tad slower than irfanview.

64 colour reduction is ok too.32 colour,I haven't used in a long while...(hmm note to self-should try it!).16 colour always needs white brought back by adjusting the palette,in irfanview at least but I see others (posted above)have this problem too.
Note:I generally start the irfan-gui with a small non-consquence picture so as to keep ram fresh...
cmd line is possible with Irfan,though it's a little odd,I think and not so well documented.

ideally,with IMGKAP,I could just go with a 256 bmp and the mc2bsbh hdr-but it consistently works for OpenCPN kaps only - I've hit a mudbank over there for some reason..

[HappySeagull]

...sorry for the blog.I avoid resampling (jpeg-bmp) too.It seems sharper.
but these jpegs are problematic in the first place...
sum:
to BMPS:256 colour,50%,no resample. less colours does not reduce file size.256 is about half of 16million size and opens faster in MAPCAL_2
to tifs..from original,not the above)127 colour,50%,no resample.

[phiggins]

OK thanks for the information HappySeagull.

I have found that using nconvert and reducing the colors to 64 works well: nconvert -out png -resize 30% 30% -colors 64 24402.jpg

but I had to modify GE2KAP to lighten the image before I called TIF2BSB so that the whites were truly white.

[phiggins]

I have uploaded to my website the version of GE2KAP that supports creating charts from NGA images (or any scanned chart) that are calibrated with MapCal.

If you want to try it, download it from:

www.gdayii.ca ...Downloads...GE2KAP

[sinbad7]

I don't know why but a downloaded NGA map of 17 MB was impossible to handle with any of my programs which just froze up through lack of memory. I run Vista with 2GB memory.
Tried at first using 'jpgopt' to compress but it also froze up. GIMP2 the same.

Tore

[phiggins]

Tore,

Which programs froze? I was able to use nconvert to change a 32gig jpg to a png and its quite fast. See format in previous post.

[phiggins]

Sorry that should have been a 32Meg not gig.

I just tried nconvert on a 24Meg jpeg on a little ACER (XP)with 1Gig Ram and it took 7 minutes but worked OK. Then I ran GE2KAP and converted to a chart in less than 1 minute.

[sinbad7]

Paul..

Must be some problem with my Acer laptop,never had this before..

Tore