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Avnav Ocharts(NG)

AvNav ochartsng is a new implementation of the AvNav ocharts plugin.
This implementation has a couple of new features:

• Now also available on Android (see below)
• Has a direct (online) Shop interface
• Can now also handle unencrypted S57 charts (after some initial conversion)
• Has more options for adapting the display
• Avoids the large disk caches that created a lot of SD card write load and a lot of CPU load
• Does not need to restart to handle newly uploaded charts
• Can utilize more cores of the processors and should run faster on many systems
• Has fewer external dependencies - especially it does not need a working X11 environment any more
• Utilizes less memory
• ...

Currently this implementation is in a beta status. So there are / could be some restrictions:

• Handling of oeRNC charts (raster charts) is still not implemented
• There could be bugs in the display or in some handling flows
• On Android you cannot use the same license for OpenCPN and for AvNav

Overview

AvNav is able to handle charts in various raster formats. So far it was unable to handle any commercial charts. The  o-charts company supplies charts for various regions of the world for usage in OpenCPN.

After some agreements with o-charts, those charts can now also be used for AvNav (starting with version 2024xxx with this new plugin - see below). At present you can use oeusenc vector-charts .

Additionally the plugin is able to handle free S57 charts (after conversion).

To display those charts in AvNav they must be rendered into raster images. This is handled by a new plugin for AvNav(avnav-ochartsng). The rendering takes place on the fly whenever tiles are to be displayed. A certain amount of rendered chart data (tiles) is kept in memory on the server to serve them fast if you switch between certain zoom levels or if you run multiple displays.

All oeSENC charts handling is performed by the plugin - including installation (you cannot install them directly via the download page). For this purpose a dedicated GUI is offered by the plugin. You enter it from the main page via (User Apps) and  Ocharts-Provider  .

Chart Types

AvNav ochartsng can handle the o-charts vector charts (oeusenc) as described in this document.
Additionally it can also handle unencrypted vector charts - like S57 charts available for download for various regions.
To use S57 charts they need to be converted into the OpenCPN format that AvNav-ochartsng understands.
For details on how to convert charts refer to Chart Conversions.

Buying and Installing the Charts

Important Hint: If you do not have a dongle from o-charts, your chart license is bound to your system. So in case of any trouble do not set up a new system (by writing an image to an SD card) but instead try to repair the system. If you set up a new system you will lose your license. I will by happy to support in case of trouble - contact e.g. via email.

To be able to buy charts at o-charts you have to create an account at their site first.
Afterwards you have to register the systems you would like to buy charts for at the o-charts site.
You have two different ways to do this - named the "online process " and the "Offline" process .
The online process requires that your system (the one running the AvNav server - not necessarily the one running the browser!) is connected to the internet.
For Android the registration of the system is only possible with the online process.

The Offline Process

This process consists of the following steps:

1. Create a "fingerprint" for the system you would like to use the charts at. In AvNav you will create it in the GUI for the plugin and download from there.
2. Upload the fingerprint to o-charts and create a system (basically assigning a name).
3. Buy charts
4. Assign charts to the system you created
5. After a short time you will receive an email from o-charts with a download link (zip file).
6. Upload charts to AvNav (via the plugin GUI).

For updates repeat steps 4, 5 and 6 (only requesting the notification mail at step 4).
For further chart sets steps 3-6.
For steps 2,3,4 and 5 you need a system with internet connectivity. You can e.g. use a laptop or an android device.
Important hint for Android: The registration of the system (Steps 1 and 2) cannot be handled using the offline process. You have to use the online process for those steps. Buying charts, assigning them, downloading and installing them can be also done with the offline process.

I created a video to demonstrate the offline process. Additionally here is a short description.

Hint: If the charts are already registered on the same system (for OpenCPN) you can directly continue at step 6 (but not for android - see restrictions above).

Creating the fingerprint

Via -> you enter the GUI of the plugin, select the "Charts" tab.

Use "Get Fingerprint" to create the fingerprint file. If you are using an o-charts dongle - just select "Get Fingerprint(Dongle)". The dongle button will only be visible if a dongle has been detected (dongle line is green).

Choose Download to save the created file on your device.

Uploading the fingerprints to o-charts

Enter the  o-charts page and upload the fingerprint.

With "Choose File" you select the file stored at step 2. Assign a meaningful name to the new system - this will be part of the mails you will receive later.

Buying the Charts

Select the desired charts from oeSENC charts.

Assigning to your System

At 1 you can assign charts to your system (in this screenshot this is not available anymore as the max amount of 2 systems are already assigned). At 2 you request the mail holding the download link (you would do the same for updates - in the screenshot: last version I have downloaded is 21, latest available is 23)

Downloading the Charts

After a short time you will receive a mail containing the download link for your charts. Download the zip file.

Uploading the Zip File to AvNav

In the plugin's GUI select "Upload Zip" to transfer the zip file downloaded in step 5 to AvNav.

There will be a progress bar during upload.

After the upload is completed the zip file will be unpacked. Some initial checks can take some time.

Unless configured otherwise, the charts will be uploaded to /home/pi/avnav/data/ocharts/charts.

If the newly uploaded chart contains updates to an already existing set, the existing set will be deactivated. You may change this later on by using Enable/Disable/Auto. Chart sets not required anymore can be deleted.

Important hint: As the charts will only be available at the o-charts page as long as they are valid just keep the downloaded zip file at a safe place. You can still upload and use those charts at AvNav ochartsng even after the validity period (but you will not receive any updates).

After all charts are successfully read the status should change to green (READY).

If the status turns to "ERROR" (red) you maybe uploaded a zip that was not built for your current system. You can check details in the log file at /home/pi/avnav/data/ocharts/provider.log.

Now the charts are available and can be used.

The Online Process

For using the online process your system (the server that runs AvNav - not necessarily the one that you run your browser on) needs internet connectivity.

It will allow you to register your system, check if it is known in the ocharts shop, list charts or updates being available for download, download and install them.
Currently the buying process and the assignments of the charts have to be done on the o-charts web site. But the GUI will contain a link button to go there.
The AvNav ochartsng will not store any shop credentials. But as you run inside a browser you can easily use your browser to store the credentials (like you do on any other web site).

Security hint: Although the communication with the ocharts shop is secured by SSL the communication between your browser and the AvNav server is not. So when you are using the online process just be sure to work within a secured network (e.g. behind an LTE router or a mobile phone hotspot) - not within a public open Wifi network.

When opening the "shop" tab you will not be logged in and you will see an info whether a dongle is active on your system or not. Via the "ShopPage" button you can directly access the o-charts web page (but better log in first...).

With tapping "Login" you will login to the o-charts shop.

When the shop already knows your current system the "Shop name" will be shown and the list of available charts/updates that have been assigned to your system (see OfflineProcess) will be visible.
If a version in the shop is newer then your local version (or the chart is not locally available) you can immediately install it.

After downloading the chart will be unpacked and can immediately be used. If it is an update for an existing chart set, the new version will become active but the old one will still be available (similar handling like uploading a chart zip file). On the chart tab you can later on delete the older version if you don't need this any more.

Important hint:
As the charts in the shop will only remain available for download as long as they are valid (one year) please store the charts additionally at a safe place. You can either do this from the shop website by requesting the charts (like in the offline process). Or you can download the chart set from the "charts" tab (Download button).

If your system is still not known to the shop you are able to register it there.

On linux systems you will be prompted for a system name but on android the system name is fixed and cannot be changed.

After you registered your system you can click the "ShopPage" link and start assigning charts to your system. When coming back to the shop tab you need to tap "Refresh" to get the list of charts that have been assigned.

Adapting the Look and Feel

As the o-charts are vector charts you can adjust their look and feel. However some limitations must be considered:

1. The modifications apply to the server's chart settings - so they will become effective for all displays.
2. If you change the look and feel all data in the internal cache is wiped and the chart tiles must be rendered from scratch. So this will (potentially) introduce some delays on systems with less computing power.

Changing display parameters is done in the plugin GUI(->), tab "Main Settings".

If you change a setting (1) it will be displayed bold. Changes will only become effective when you click "Update Settings"(2).
When you changed the settings the chart display will be rebuild. This will typically cause a small delay with no display at all.

By selecting "Cancel" you can revert your changes. "Defaults" will reset to the built-in defaults. Most parameters are similar to the ones you find at  OpenCPN settings.

The following parameters are available.

Name	Meaning	Default
Show Text	show text for chart objects	true
Important Text Only	hide less important text	false
Light Descriptions	show descriptions for lights	true
Show Depths	show soundings	true
Show Quality	show extra objects indicating the quality	false
Chart Information Objects	show informational objects	true
Buoy/Light Labels	show labels for buoys and lights	true
National text on chart	show national text	true
Show Lights	show lights	true
Show Anchor Info	show anchoring information	true
Color Scheme	The color scheme to be used for the chart display	DAY_BRIGHT
Chart Bounds	Show the chart bounding boxes	true
Reduced Detail at Small Scale	reduce details at lower zoom levels	true
De-Cluttered Text	improve text positioning	true
Display Category	Base, Standard, All, User Standard	Standard
Graphics Style	Paper Chart, Simplified	Paper Chart
Boundaries	Plain, Symbolized	Plain
Colors	4Color, 2 Color	4 Color
Text Font Size	Scaling for text on charts	1 (ca. 12px)
Soundings Font Size	Scaling for soundings	1 (ca. 12px)
Scale	Base scaling. Higher values for more details on lower zoom levels	1
UnderZoom	Number of zoom levels to downscale higher resolution chart tiles if no chart tile is available at the requested zoom level.	4
AreaUnder	If with in the under zoom range still no charts have been found, just try some lower zoom layers - but only display the areas (land, depth) - no other information. Be careful when increasing this as this could impact the performance a lot.	2
OverZoom	Number of zoom levels to upscale a lower resolution chart tile if is no chart tile is available with better resolution. Hint: Scale, UnderZoom and OverZoom, AreaUnder heavily influence the cost of the rendering process as they determine the number of charts to be processed to generate a single chart tile. Lower values normally mean less charts (i.e. being faster) - but there could be white areas between chart tiles. The defaults should be a good compromise.	4
Scale Tolerance	When scaling the map or the symbols (symbol scale) all the symbols have to be rendered on those scaled values. To avoid too much additional symbols you can allow a small tolerance here.	0.1
Rotation Tolerance	When Objects (symbols, lines, lights... have to be rotated on the map for each different angle a new symbol has to be created. To optimize performance and memory usage we can allow a small tolerance here so that a couple of different angles can use the same rotated symbol (in degrees)	2
SymbolScale	Scale the display of symbols. Some of the symbols are build out of raster data - so a scale > 2 could already make theme look very ugly.	1
Depth	Unit for soundings(Meters, Feet, Fathoms)	Meters
Shallow Depth	Adjust to your needs	2
Safety Depth	Adjust to your needs	3
Deep Depth	Adjust to your needs	5

At the tab "Detail Settings" you can switch on/off particular chart features. Those detail settings will only become effective when using the display category "User Standard".

Feature Info (Object Query)

When you click on a chart you will have AvNav's Feature info. This will be extended by some important information found around the click position.

By clicking "Info" you can view the raw information from the chart.

By clicking the blue chart name you can get some more information about the chart that this object belongs to.

Installation

Linux/Raspberry

The plugin is available as a debian package.
As the plugin is currently in a beta phase, the packages are still not part of the official repositories.

For the AvNav Images the necessary packages can be found in the beta repository. To enable it you can edit the file /etc/apt/sources.list.d/extra.list to enable the beta repository.
Start the editor with:

Just remove the hash mark at the debpreview line. Afterwards you can install the package normally with the avnav updater:

• avnav-ochartsng

If you want to do this from the command line execute:

If you are working on other images you should add the repository from free-x (adapt "bullseye" to your debian release):

Refer to the AvNav package install description.

Alternatively you can download the packages them from the daily builds directory.

To use one of those packages just download and install the package (replace the version by the one you want):

You can also download to a PC, transfer by scp/WinScp to the pi and install then.

AvNav-ocharts and AvNav-ochartsng Together

When you install the new avnav-ochartsng-plugin you will get some conflict with the existing ocharts plugin. At the end both will try to use the same port - so at least one of the two will fail to start.
The suggested solution is to disable the ocharts-plugin on the  server/status page.
Additionally enable the "useLegacy" switch in the PluginConfig of the ochartsng plugin. This way the new plugin will also use all the charts that you installed with the old one.

If you would like to run both plugins in parallel change the port of the ochartsng plugin to e.g. 8083. Running both in parallel should only be done if your system has sufficient RAM (at least 2GB).

Android

On android there is an extra app that will contain the ochartsng.

See AndroidApp below.

Releases

You can find all releases and intermediate developer builds (daily builds) at:

• Releases
• Daily Builds

Release Versions

-- none yet --

License Notes

Using the charts in AvNav with the oesenc-pi plugin has been agreed with o-charts and therefore is inline with their license conditions.
You have to agree to the license conditions of o-charts
Especially it is not allowed to copy the charts or use them on other than the licensed systems.

Access to the charts in AvNav is only possible from within the local net. You can connect at most 5 devices (Clients) at the same time.

For software licenses see the Readme.

Plugin Configuration

Linux only. For Android refer to Android/Settings.
Some of the plugins settings can be changed on the server/status page at "plugins/system-ochartsng" .

Those are:

Name	Meaning	Default
port	Http port	8082
debug	log level for <datadir>/ocharts/provider.log. <datadir> on a raspberry is /home/pi/avnav/data	1
memPercent	The amount of memory (percent of the system memory) that the plugin (correctly: the provider process) will use. If this value is not set (or set to low) the provider will use an internal minimum. This potentially could be rather low - especially when using raster charts. If it is very low the provider must open and close chart files very often and this will slow down it's operation. If you have enough memory (e.g. 2GB) you can increase speed by setting the memory to 1GB .	50
tileCachekb	KB of memory to be used for the internal tile cache (set to 0 to disable it for some testing)	40960
useLegacy	Also use the charts that have been installed with the old avnav-ocharts-plugin. By activating this you can disable the old plugin in the settings and just use all the charts you already installed.	off

Android App

AvNav OchartsNG also runs on Android and provides charts for the AvNav android app.
The Ocharts support is built into a separate Android App - avocharts.

Currently the app is not (yet) available in the google play store as it is still in beta status. So you need to download it from the daily builds directory and install it (allow external sources).

After you started up avocharts for the first time you can adapt some settings.
When you see this picture the real ocharts provider process is still not running - it will start up when you tap "start".

Later it will not be necessary to start the avocharts app by hand - it should normally being started automatically when AvNav starts up. But directly starting the avocharts app can help to troubleshoot as you can get access to the output and log of the chart provider.
Please consider that the auto start will only work for apps of the same type - i.e. an AvNav release app can only start an avocharts release  app and an AvNav beta app can only start an avocharts beta app.
So when you install the avocharts beta together with the "normal" AvNav app from the store you need to start avocharts by hand before you can use the charts in AvNav.

Settings

To adapt settings tap on the shown settings or on the settings icon on the upper right.

Name	Explanation	Default
Port	The IP Port the provider process will use. If you get errors when you start the provider and see something like "address already in use" in the output (tapping the out button on the main page) you maybe need to change the port	8082
LogLevel	0 - errors, 1- info, 2- debug	1
Shutdown	Time (in seconds) the provider will wait for a heartbeat from AvNav before it stops (only active when started by AvNav)	30
Memory	Allowed Memory usage (%) of the system memory	50
Testmode	internal testing only	false
Use alt key	See below for the hints about Release/Beta Versions
Disk symbol (upper right)	Save your key (See below for the hints about Release/Beta Versions)

When done with the settings tap the back arrow.

You can now start the chart provider by tapping "START".

When the provider process is up an running you will see the indication in the notification bar. If something goes wrong just try to have a look at the output (tapping "OUT") or the log (tapping "LOG").

Tapping "APP" will open up a browser window with the ochartsng app - the same view like you get from within AvNav.

You now can e.g. register at the ocharts shop (on android this is only possible using the Online Process).

Beta and Release Versions

Due to the way that the ocharts license daemon is working you will normally not be able to use charts that you installed with the release version within the beta version and vice versa.
To overcome this problem you can export the necessary information from the app version that you used to assign the charts and import this in the different version. Hint: You still can only use this on the same android device!
To export a key tap the disk symbol on the settings screen within the app and store the file at a safe place. When you later use the alternative version, select "use alternate key" , tap on the key value and import the saved key file there.
You can easily check if your app has the correct key by going to the shop page and log in. When the shop recognizes your current key it will show the system name - see Online Process.

Please also consider the automatic startup relations between the Beta and Release version.

Technical Details

The charts are provided by an executable that normally serves at port 8082.
Communication with AvNav is handled by an AvNav plugin on linux and by the avocharts app on Android.

The GUI is a reactjs app that is also provided by the executable. It is integrated into AvNav as a User App.

You will find the complete code at GitHub.

You install into /usr/lib/avnav/plugins/ochartsng. The data directory is /home/pi/avnav/data/ochartsng. You can set some additional parameters for the AvNav plugin by editing avnav_server.xml. Normally this is not necessary at all.

You can separately set the directory for all settings and the charts:

Chart Conversions

Unencrypted vector charts like S57 charts have to be converted into the internally used "SENC" format before they can be handled.
There are 2 Options to convert such charts.

Converting with AvNav (since AvNav 20240520)

The avnav-ochartsng-plugin adds a chart converter to AvNav's importer. This converter contains a python script to convert S57 data into a zip archive that can be uploaded.
To convert your S57 charts simply upload a zip with the charts to AvNav's importer after you installed the plugin.
If you run AvNav and ochartsng on linux the converted charts will be automatically uploaded and activated to ochartsng.

If you run ochartsng on a different system (e.g. on Android) you need an installation of AvNav either on a linux machine or on Windows.

Ochartsng itself cannot run on Windows but the conversion tooling can. So after you installed AvNav on Windows just open the "Update" Dialog and enter the Url of the ochartsng-s57 converter for Windows:

• release: https://www.wellenvogel.de/software/avnav/downloads/release-ochartsng/latest/ochartsng-latest.zip
• daily: https://www.wellenvogel.de/software/avnav/downloads/daily-ochartsng/latest/ochartsng-latest.zip

Afterwards let the conversion run and when finished download the converted chart (.zip). This zip can directly be uploaded to ochartsng both on linux and Android.

Converting using OpenCPN

If you already have a computer with OpenCPN up and running you can let OpenCPN convert the charts. To do so you need to activate the charts in OpenCPN. On the OpenCPN settings / tab "chart files" just click "Prepare all ENC Charts".

This will create a lot of files with the s57 extension in the OpenCPN directory (~/.opencpn on linux). Just pick the ones with similar names like your s57 charts, copy them in a new, empty directory with a name that explains the chart set. Afterwards create a text file "Chartinfo.txt" in this directory with just one line of text:

ChartInfo: nameOfTheChart

Create a zip archive from this directory so that the zip archive has this directory inside. This archive can be uploaded to AvNav ochartsng.
On Linux there is a script to automate this collection process.