CM93 charts - limit area...

[bushtor]

Hi,

As many others here I am using the CM93 V2 charts for OpenCPN.

However I would like to only keep or extract the files / folders for my own country and surrounding coastlines.

Is it possible to find out which of the CM93 folders to copy for a certain geographical region?

Thanks for comments on this

regards Tor

[cagney]

It's all in the friendly manual........
Installing Charts | Official OpenCPN Homepage
Scroll down until you see the the CM93 paragraph.

Thomas

[SoggyPaws]

I know this is an old thread, but here's a tip. When I read the informative OpenCPN help file linked above, I was a little boggled trying to translate that into the areas I was interested in. Here's something much easier:

1. Zoom out to the general view you are interested in (in OpenCPN)
2. Switch OpenCPN into non-quilted mode (F9) (you know you are there when the rounded bubbles showing chart coverage at the bottom of the screen become squared bubbles).
3. Right click on the map and select CM93 Offset Dialog
4. Note the numbers in the left-most column. These are the folders you want to get for the area you are looking at.

For example, using this procedure with the chart showing US East Coast, Gulf of Mexico, Caribbean results in 4 chart areas: 02700720, 02700840, 03900720, 03900840. Copy these folders, and the files in the root directory, and you should have coverage for just that area.

In general, you can greatly reduce the size of your CM93 data file, if you limit the areas of interest. Charts for the entire world covering only 40N to 40S are 1/3 the size of the whole CM93 folder. (370 MB vs 1.x GB). These are the folders 0150xxxx and 0270xxxx.

[travellerw]

Ok I have to ask the question..

Why do you care? I can't think of any device I own where 700mb would make a difference. Heck, even my tablet has 128GB of space, so 700mb is barely a dent! Frankly I keep the entire CM93, plus Vector and BSB coast guard charts for the whole USA. Its about 7GB.

[SoggyPaws]

I am trying to get OpenCPN set up on my Samsung Galaxy S3 phone. It's already a little slow because of updates to Android. Though I have 64GB SD card, my SD card takes forever to write to (reported 11 hours to write the whole CM93 directory to it!).

Also, I'm likely to eventually set up the same setup on 2 other similar devices (my husband's phone and a 7" table we have), so I thought I'd play with it. The table (a 2012 Google Nexus) has no expandable storage, so space IS limited on it.

However, I've run into an issue that my simple summary might not be picking up enough files. (Going back to re-read the OpenCPN help file more closely now). I'll report back later.

[Liburnian]

Originally Posted by travellerw

Ok I have to ask the question..

Why do you care? I can't think of any device I own where 700mb would make a difference. Heck, even my tablet has 128GB of space, so 700mb is barely a dent! Frankly I keep the entire CM93, plus Vector and BSB coast guard charts for the whole USA. Its about 7GB.

Raspberry Pi? Or just enjoying to do or make something workable without all the unnecessary crap (including spyware, malware, commercials etc.).

[travellerw]

Originally Posted by Liburnian

Raspberry Pi? Or just enjoying to do or make something workable without all the unnecessary crap (including spyware, malware, commercials etc.).

Pi has an SD card slot.. 32GB cards are like $12... Still not seeing why!

[Liburnian]

Trawellerw, you're right. I didn't delete it on my RPi. Maybe I'll use some exotic charts, when reading a travelogue Nevertheless I've asked myself, why to have all the planet on that SD. Better to upload skychart.

[Yens]

I've created a utility to subset CM93 charts, based on a simple route file created from within OpenCPN. See here for details: Utility to create subsets of CM93 charts

[yachtvalhalla]

Originally Posted by SoggyPaws

I am trying to get OpenCPN set up on my Samsung Galaxy S3 phone. It's already a little slow because of updates to Android. Though I have 64GB SD card, my SD card takes forever to write to (reported 11 hours to write the whole CM93 directory to it!).

Also, I'm likely to eventually set up the same setup on 2 other similar devices (my husband's phone and a 7" table we have), so I thought I'd play with it. The table (a 2012 Google Nexus) has no expandable storage, so space IS limited on it.

However, I've run into an issue that my simple summary might not be picking up enough files. (Going back to re-read the OpenCPN help file more closely now). I'll report back later.

Sherry,

I've found that you need all the subdirectories except 0030, 0390 and 0450 sets. This reduces the cm93 folder to 559MB for the region 40N to 40S.

Looks good on OpenCPN on the computer but does give some overlap to 60N and 60S on the Android. Working on that.

Terry

[Yens]

I've updated the subset utility to v0.7 and included a GUI frontend - all available from here: http://bit.ly/cm93utility