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Old 24-07-2016, 16:11   #1
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Delete individual charts?

OK, it's a newbie (to OpenCPN) question, but I've been unable to find an answer.

Can I "easily" delete individual charts in OpenCPN?

I installed the CM93 set, but really only need a few regions. I can decode which I want and deleted all below the equator from the installed library. I told OpenCPN to Force a New DB rebuild, and the underlying world map shows the Southerly Hemisphere as greyed out, but continues to show the chart outlines there, and panning has slowed considerably.

I'm assuming OpenCPN is spending time looking for files that are no longer there, but is there a simple way to update it's catalog, or do I delete them all and "just" reinstall only the subset I want?

THanks
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Old 24-07-2016, 16:20   #2
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Re: Delete individual charts?

is it really slower? sounds like a possible bug. Why do you need a subset, do you lack the disk space?


Try deleting the cm93 directory that opencpn generates located in the same folder as the log and config file
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Old 24-07-2016, 16:49   #3
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Re: Delete individual charts?

Quote:
Originally Posted by boat_alexandra View Post
Try deleting the cm93 directory that opencpn generates located in the same folder as the log and config file
Thanks and Yes that worked. That was going to be my next try.

Would be nice if OpenCPN offered an easy way to manage the chart portfolio within the program.

I guess I am kinda old-school and prefer to keep the footprints of my data and applications small as they certainly do seem to accumulate mass storage requirements over time. Plus, I plan to run on a Surface with only an SSD with somewhat limited storage, and at least fiddle with an android tablet.

Thanks again
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Old 24-07-2016, 20:54   #4
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Re: Delete individual charts?

Hopefully this gets merged soon

https://github.com/OpenCPN/OpenCPN/pull/683

Reduces disk requirements to less than half without compromising performance. For now you can compile from source and give feedback
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Old 25-07-2016, 01:31   #5
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Re: Delete individual charts?

jamhass,

compressing charts or textures might makes sense when you have a small computer like RaspberryPi. For a normal computer it is useless and has no benefit.

If you want to delete charts of the cm93 bundle which you don't need you have to know how cm93 is organized. There are about 144 subfolders in a cm93 folder which are named as numbers.

The system for c-map is very simple. All folders contain segments of 20 x 20 degrees.
00300000 means 80S 0E, 00300060 means 80S 20E, 00900120 means 60S 40E. The first 4 digits is south to north 0150=40S +20 north, 0210=20S, 0270=0S (equator and 20 degrees north), 0330=20N, 0390=40N. The last 4 digits is East from 0 meridian.. 0060=20E, 0120=40E, 0180=60E, 0240=80E, and so on 0480=160E, 0540=180W, 0600=160W and so on..

The folders in the next level is a - z, where z is scale 40x40 degrees,
a is20x20 degrees, b is 10x10 degrees, down to f and g which is scale of
20x20 arcminutes, which is harbour level.

Using this explanation you are able to delete the charts you don't want to keep.

Gerhard
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Old 25-07-2016, 10:35   #6
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Re: Delete individual charts?

Gerhard:

Thanks, Yeah I know how CM93 is organized and wrote a disgustingly simple spreadsheet to interpret the filenames. Big help in deciding which to delete.

Not currently planning to circumnavigate so can eliminate most of them .....
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