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[Colleaux]

I am trying to find a way to overlay a satellite image from Earth Explorer to Open CPN. I am sure there are many people who have done this. Can anyone point me in the correct direction please?

Thanks

[Jon Hacking]

Originally Posted by Colleaux

I am trying to find a way to overlay a satellite image from Earth Explorer to Open CPN. I am sure there are many people who have done this. Can anyone point me in the correct direction please?

Thanks

First, welcome to CF, Colleax. We hope that we can help your cruising experience.

I don't know about Earth Explorer, & I haven't heard of anyone making charts from it. We make our charts using satellite imagery from ArcGIS, Bing, & Google Earth, as well as nautical charts from CMap & Navionics. But I make them as mbTiles, using SAS Planet (& Sat2Chart as my automation engine).

We now publish our charts for cruisers to download. They cover the entire coastlines of over 30 countries, including the eastern Caribbean, Galapagos, Micronesia, Solomon Islands, much of SE Asia, much of the tropical Indian Ocean, & even some of tropical East Africa. They include all zoom levels from Z10-18, which is enough to see individual coral heads (which are exactly where charted). Other downloadable charts can be found in Bruce Balan's Chart Locker, as well as Sherry McCampbell's (Soggy Paws) download page.

Finally, if you want to make your own high-resolution charts, the tools & data are all free on the web. I publish a How-To guide to Making mbTiles that gives you step-by-step instructions.

OK, not quite what you're looking for, but perhaps this will help you.

[Colleaux]

Thanks for the direction Jon.

What I am attempting to do is have a satellite image overlayed on Open CPN in real time to allow comparison between the downloaded NOAA (or other) charts and the "real" world. A few years ago I did this with Google earth but of course cannot find my notes anymore. Not that there is ever a discrepancy between charts and sat images but just in case.....

i will go back to playing with GE again.

Thanks again

Regards

Steve Colleaux

[Jon Hacking]

You're welcome, Steve.

Our charts don't exactly "overlay" other charts, but by using "Chart Groups" you can quickly switch between charts with just a single keystroke. This is MUCH easier than trying to use the "piano-keys" at the bottom of the screen.

So when I want to correct, say, my CM93 charts to more closely conform to reality, I:

• switch to a satellite view
• drop marks at the tips of headlands, or other notable features
• switch back to my CM93 charts
• turn off quilting (F9)
• adjust my CM93 charts to get the best fit to my dropped marks
• turn quilting back on (F9) & clean up my dropped marks

For non-adjustable charts, using chart groups will at least allow you to quickly & easily see how well your charts conform to your satellite imagery.

FWIW, we started with just Google Earth in 2014, but have now moved on to SAS Planet, which gives us GE as well as many other forms of satellite imagery.

[Rasbats]

My photolayer_pi (master catalog) uses lat/lon tif images. Transparency of the satellite image can be adjusted to show the chart underneath.

SASPlanet can produce these images. They need to be saved in lat/lon format, not mercator.

Mike

[morriep]

What would I need to enable my Raymarine P/70 pilot controller to receive waypoint data instructions from my Acer laptop using Open CPN?
Morrie

[Wilyum]

Is there a way to toggle between charts like you can with SASPlanet using keyboard shortcuts? N - Navionics, G - Google Satellite etc. Thanks.

[nohal]

Yes, define chart groups and use numerical keys to switch between them

https://opencpn.org/wiki/dokuwiki/do...s%5B%5D=groups

[Wilyum]

Originally Posted by nohal

Yes, define chart groups and use numerical keys to switch between them

https://opencpn.org/wiki/dokuwiki/do...s%5B%5D=groups

Thanks!

[andreatardini]

Good day, I have a problem. Following picture of exercise. Using rya training almanac. Page 55.
10:35 DST August 11th is 4 hours before Namley Harbour High water, not 2. Correct ?

Thank you for your comments.

Andrea

[Jon Hacking]

Does anyone know if there's something inherent in OpenCPN that prevents it from displaying an mbTile that crosses the 180?

I'm making mbTiles of Fiji, & the 180 cuts through the right end of Fiji (the dateline makes a jog there). I can create an mbTile that goes up to the 180 on each side, but when I load it into OpenCPN, I get very strange behavior:

If the 180 is on the left side of my screen, then ONLY the mbTile on the right is displayed, & if the 180 is on the right side, then only the mbTile on the left is displayed.

If I grab the chart & start panning OpenCPN, when the 180 crosses the center of my screen, the mbTile that has been visible disappears & the mbTile that's been invisible suddenly appears!

If I try to construct an mbTile that crosses the 180, OpenCPN doesn't display it at all (although I don't know the quality of the tool I use to build that mbTile - it's the Merge_MbTiles function of Paul Higgins' Sat2Chart program).

Is this expected behavior?

Or have I found an OpenCPN bug?

[bdbcat]

Jon.
Most likely a bug. IDL crossings are always problematic to code.
Please post a github Issue, and we'll take care of it.


Thanks for the catch
Dave

[barnaclebill22]

I use a headless RPI4 for SignalK, and just installed VNC and the flatpak OpenCPN. I feel like I've configured something wrong because OpenCPN is so laggy that it's unusable. Screen updates like zoom in or out take almost a second, and clicking more than once hangs everything for a while.

top shows the RPI (6.1.21-v8+) is mostly idle. I haven't connected a display and keyboard yet but even if that works, I want to use VNC on my boat, from a waterproof tablet.

I also tried same VNC client to an old Windows laptop on the same wifi network, and that works fine. Also, I can watch a youtube video on VNC to the RPI without any problems.

What am I doing wrong?

[cas206]

Originally Posted by barnaclebill22

I use a headless RPI4 for SignalK, and just installed VNC and the flatpak OpenCPN. I feel like I've configured something wrong because OpenCPN is so laggy that it's unusable. Screen updates like zoom in or out take almost a second, and clicking more than once hangs everything for a while.

top shows the RPI (6.1.21-v8+) is mostly idle. I haven't connected a display and keyboard yet but even if that works, I want to use VNC on my boat, from a waterproof tablet.

I also tried same VNC client to an old Windows laptop on the same wifi network, and that works fine. Also, I can watch a youtube video on VNC to the RPI without any problems.

What am I doing wrong?

What about memory usage? RPI4 comes in 2, 4, and 8 Gig models. Does top show lots of swap memory in use?


Another factor to consider, check this document page for openplotter regarding opencpn, https://openplotter.readthedocs.io/e...encpn_app.html. There is a note that says, "At the time of writing this manual, OpenCPN Flatpak is the best option for touch screens because it allows right-clicking and two-finger zooming. However OpenCPN Flatpak may not work well in headless environments."


It doesn't define what "not work well" means, it could mean controls or it could mean performance.
Is your distro debian based? Can you install the package from your distro repositories? Try that.

[cas206]

Another thing to try: Go to opencpn options->Charts. Remove the chart folders. Check to force a database rebuild. In other words, try OpenCPN without charts to see if there is a performance issue due the charts being used.