=== not for Android ===
- Buying and Installing Charts
- Adapting the Look and Feel
- License Hints
- Technical Details
AvNav is able to handle chart in various raster formats. Until now it was unable to handle any charts you can buy officially. There is the company o-charts that is supplying charts for various regions of the world for the usage in OpenCPN.
After some agreements with them those charts can now (starting with version 20200515 with a plugin - see below) also being usaed for AvNav. Until now you can use oesenc vector-charts.
To use those charts in AvNav they have to be rendered into raster images. This is handled by a new plugin for AvNav(avnav-ocharts). This rendering takes place on the fly whenever the charts should be displayed. This way those charts can be used the normal way - without really dealing with the rendering process.
All handling for those charts is completely done by the plugin - including the installation (you cannot install them directly via the download page). There is an own GUI at the plugin for this purpose. You can reach it from the main page via (User Apps) and Ocharts-Provider .
Important Hint: If you do not own 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 loose 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.
This process consist of the following steps:
- Creating 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.
- Uploading of the fingerprint to o-charts and creating a system (mainly assigning a name).
- Buying charts
- Assigning charts to your created system
- After a short time you will receive an email from o-charts with a download link (zip file).
- Uploading the charts to AvNav (via the plugin GUI).
For updates you will have to repeat steps 4,5 and 6 (only requesting the mail at step 4)
For further chart sets steps 3-6.
For steps 2,3,4 and 5 you will need a system with internet connectivity. You can e.g. use a laptop or an android device.
For this process I created a video to show the basics. Additionally here is a short description.
Hint: If the charts are already registered at the same system for OpenCPN you can directly continue at step 6. Alternatively you could also configure the OpenCPN chart directories with o-charts at the plugin .
1. Creating the fingerprint
Via -> reach the GUI of the plugin, select the tab "Charts".
Use "Get Fingerprint" to create the fingerprint file. If you are using an o-charts dongle - just use "Get Fingerprint(Dongle)".
Use the dialog to save the created file on your device.
2. Uploading the fingerprints to o-charts
Go to the o-charts page and upload the fingerprint.
With Choose File select the file you have stored at step 2. Assign a meaningful name to the new system - this will be part of the mails you will receive later.
3. Buying the Charts
Select from oeSENC charts the ones you want to buy.
4. Assigning to your System
At 1 you can assign charts to your system (in my pictore not possible any more as I already have assigned the max amount of 2 systems). At 2 you trigger the mail with the download link (you would do the same for updates - in the picture: last version I have downloaded is 21, newest available is 23)
5. Downloading the Charts
After a short time you will receive a mail containing the download link for your charts. Download the zip file.
6. Uploading the Zip File to AvNav
In the GUI of the o-chart plugin use "Upload Zip" to transfer the zip file you have downloaded in step 5 to AvNav.
There will be a progress bar during upload.
After the upload is finished the zip file will be unpacked and there will be some initial checks on it (this can take some time).
If you did not configure anything the charts will be uploaded to /home/pi/avnav/data/ocharts/charts.
After all checks have been passed the dialog will show up asking you to restart the plugin to make the charts usable.
If the newly uploaded charts have been an update for an already existing set the existing one will be deactivated at restart. You can change this later on at the GUI. If there are chart sets that you don't need any more you can delete them here.
During the restart there will be a couple of error messages but after app. 30s the status should at least be yellow (the plugin is now reading all charts).
After successful reading of all charts the status should change to green (READY).
If the status will change to "ERROR" (red) you potentially did upload a zip that was not 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.
At the "Status" tab you can see some more details.
In the picture you see that after uploading a process ("Cache Prefill") started that will pre-render chart tiles. This will help to prevent lags that otherwise would (potentially) occur due to the limited resources of the pi. The cache prefill will pick a couple of tiles for the chart set and will render them into a cache file.
Anyway you can start using the charts immediately.
As already mentioned there is a chance that lags will occur when you are using a particular range/zoom of the chart for first time (you will notice this espacially on the smaller/older pi's). After the first usage of a range the necessary tiles will be in the cache and there should be no lag any more.
As the o-charts are vector charts you can adapt their look and feel. Anyway there are some limitations you have to consider:
- The adaption takes place at the AvNav server - so it will become effective for all displays.
- If you change the look and feel all the data in the cache has to be wiped and all chart tiles must be rendered newly. So this will (potentially) again introduce some lag on smaller/older systems. Anyway the automatich cache prefill process starts again to pre-render a lot of tiles.
Changing the display parameters is done in the plugin GUI(->), tab "Main Settings".
If you change a setting (1) it will be shown bold. Changes will only become effective once you click "Update Settings"(2).
Using Cancel you can revert your changes. Defaults will set to the built-in defaults. Most of the parameters are similar to the ones you find at OpenCPN settings.
The following parameters are available.
|Show Text||Show text for chart objects||true|
|Important Text Only||hide less important text||false|
|Light Descriptions||show descriptions for lights||true|
|Extended Light Sectors||show sectors for lights||true|
|Show Depth||show soundings||true|
|Chart Information Objects||show special chart object infos||true|
|Buoy/Light Labels||show labels for buoys and lights||true|
|National text on chart||show national text||true|
|Show Lights||show lights||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||All|
|Graphics Style||Paper Chart, Simplified||Paper Chart|
|Colors||4Color, 2 Color||4 Color|
|Text Font Size||Scaling for text on charts||1 (ca. 12px)|
|Soundings Font Size||Scaling for soundings (since oesenc-pi 4.2.x)||1 (ca. 12px)|
|Scale||Base scaling. Higher values for more details on lower zoom levels||2|
|UnderZoom||Number of zoom levels a higher resolution chart will be downscaled if there is no chart at the requested zoom level.||1|
|OverZoom||Number of zoom levels a lower resolution chart is upscaled if
there is no chart with better resolution.
Hint: Scale,UnderZoom and OverZoom heavily influence the cost of the rendering process as they determine how many charts have to be considered when generating one 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.
|Depth||Unit for soundings(Meters, Feet, Fathoms)||Meters|
|Shallow Depth||Adapt to your needs||2|
|Safety Depth||Adapt to your needs||3|
|Deep Depth||Adapt to your needs||6|
At the tab "Detail Settings" you can switch on/off particular chart features.
You can install the new plugin as packages on AvNav images. For the Headless Images the packages are already available in the repository. You need to install
For avnav-ocharts-provider you need at least version 20200606. The package avnav-oesenc is the oesenc-pi plugin - repackaged to install into /usr/lib/avnav/plugins/ocharts to avoid conflicts with a parallel OpenCPN installation.
sudo apt-get install avnav-ocharts-plugin avnav-oesenc
sudo systemctl restart avnav
If you are working on other images you should add the repository from free-x:
You can also see the packages in the release list below. To use one of those packages (if it is not in the repo yet or if you need an older one) - just download and install the package (replace the version by the one you want):
wget -O avnav-ocharts-plugin_20200606-raspbian-buster_armhf.deb https://www.wellenvogel.net/software/avnav/downloads/release-ochartsplugin/20200606/avnav-ocharts-plugin_20200606-raspbian-buster_armhf.deb
sudo dpkg -i /home/pi/avnav/avnav-ocharts-plugin_20200606-raspbian-buster_armhf.deb
sudo systemctl restart avnav
- 20200710 package
- You can now set the directory for the charts - see details
- When uploading charts it is checked if those charts can be read. Otherwise the upload is rejected.
- No errors in GUI any more when restarting the provider
- correctly work on a vfat partition (as used by avnav touch)
- 20200705 package
- correct a problem in the OpenCPN plugin that could potentially stop it from decoding charts after running for a long time.
- 20200606 package
- first version
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 systems then the ones you have licensed them for.
Access to the charts inside 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.
The charts are provided by an executable on the raspberry pi that
normally serves at port 8082. This executable loads the oesenc-pi OpenCPN
Communication with AvNav is handled via an AvNav plugin.
The GUI is a reactjs app that is also provided by the executable. and is integrated into AvNav as a User App.
You will find the complete code at GitHub.
You install into /usr/lib/avnav/plugins/ocharts. The data directory is /home/pi/avnav/data/ocharts. You can configure the AvNav plugin within avnav_server.xml. Normally this is not necessary at all. If you need to configure anyway this has to be done below the Plugin-Manager.
For a list of available options refer to the description in the plugin source code.
Normally the recommendation is anyway to upload the zip files like described at charts .
In this example the directory is set to
/home/pi/avnav/data/charts/ocharts (normally it is located at
/home/pi/avnav/data/ocharts/charts). This could be helpful on the touch image as only in
/home/pi/avnav/data/charts there is sufficient disk space.