NOAA ENC Charts Question

[pkrawetzky]

Maybe it's something I'm doing wrong or how I've downloaded/unzipped the ENC charts but maybe someone could explain this.

When I use the ENC charts it's seems every move I do it goes into some type of S57 SENC File Create mode where it seems to scan the ENC charts for soundings, hazards, wrecks, etc and the display of the actual chart is delayed because of this. When I use the RNC charts, this doesn't happen.

Is there something I am doing wrong? It just seems to do this at random times when I move the chart or zoom in/out. Guess maybe I don't understand the ENC chart system.

Any help to understand this would be much appreciated.

[nohal]

pkrawetzky...
Every S57 cell is converted to our internal format when it is first accessed for performance reasons. You should not see the dialog anymore when you access the same chart again.

Pavel

[pkrawetzky]

It seems to perform the same create function on charts I've looked at. Maybe it's just the zoom level that is causing this to reoccur.

Is there any way to do this after downloading the charts? It can take up to 2 minutes to perform this function meanwhile the charts are not accessible.

[transmitterdan]

It only does this once per chart when it first becomes visible. There is a way to force OpenCPN to do this for every ENC chart in your chart database all in one go. It can take a long time but I do it right after updating all my ENC files. Then I never see that dialog about SENC again.

Here is what I do in Windows:

1) Download all my charts and unzip them into my normal folders. I put each ENC region in its own folder but that's just how I do it. It doesn't matter for this discussion except that you should download all the charts you plan to update with OpenCPN not running.

2) Run OpenCPN from the command line with this command:

%ProgramFiles(x86)%\opencpn\opencpn.exe" -unit_test_1

You can also create a shortcut with the above command line and put it on your desktop along side the normal OpenCPN icon. Each time you do a big chart download from NOAA just double click this icon and go have a cuppa. Once it is finished close OpenCPN and then reopen it from the normal icon. You should never see the SENC little green bar again until you download new charts. Only run this unit_test_1 version once after you download new charts. It can take a long time and you don't want to do this every time you run OpenCPN.

[nohal]

Yes, there is, run from the command line with -unit_test_1 parameter - it will consequently access all your charts.
And BTW, make sure there are no spaces in the path to your charts - although I never could reproduce it, people sometimes report that in such case, the conversion process is repeated when they access the charts.

Pavel

[pkrawetzky]

Ok I'll give this a try. Is this in the users guide somewhere? I didn't come across it.

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[nohal]

Yes, it is in The Command Line | Official OpenCPN Homepage and http://opencpn.org/ocpn/installing_charts

[pkrawetzky]

My bad I should have mentioned I'm running this on Ubuntu Linux not windows. Is there a similar parameter?

Sent from my SCH-I545 using Cruisers Sailing Forum mobile app

[nohal]

Exactly the same.

 Linux Usage: opencpn [-unit_test_1] [-p] [-no_opengl] [-fullscreen] [-rebuild_gl_raster_cache]

[transmitterdan]

Parameters are the same on all platforms.

[pkrawetzky]

This definitely resolved my issue, thank you all for the quick response. After re-reading the option description I see the reference to SENC and get it now

Not sure I'm liking ENC charts though, I've noticed they don't seem to be as accurate as RNC charts. For example, on the Mystic River the channel shown on the chart runs right into a set of docks but on the RNC charts it is correct. I'm thinking ENC is not as accurate?

Just curious what others use...

[transmitterdan]

Can you give a precise coordinate where ENC and RNC charts don't match?

[pkrawetzky]

Sure start at 41 19 05.984N and 071 59 15.942W. That is the start of the Mystic River in Connecticut. As you go up river you will notice the channel on the ENC runs right into the docks vs RNC runs parallel to the docks.

[pkrawetzky]

Ok I changed a few options on the vector display screen and it identified the channels with more precision. So it now looks much better.

[jstevens]

I placed a waypoint (Red X) at the end of the jetty near the start of the Mystic River channel and then took screen captures of the RNC and ENC charts of this part of the channel. The only difference I can see between the two charts is that there are dashed lines on the RNC chart that appear to represent the limits of the channel. These dashed lines do not appear on the ENC screen capture. Other than that the charts depicted appear to be the same.
IMO, the inclusion of those dashed lines in the RNC chart does not represent an increased accuracy.

RNC Screen Capture: 2015-01-14_0735 - jstevens8352's library
ENC Screen Capture: 2015-01-14_0737 - jstevens8352's library
Waypoint Screen Capture: 2015-01-14_0738 - jstevens8352's library

John

Edited to add: On closer look the channel limits dashed lines do appear on the ENC chart, they are just lighter.