The Electronic Charting "Zoom Problem"

[RhythmDoctor]

Originally Posted by Dockhead

Sure, if you want to look at it that way -- it's the choice of ordinary vector charts like we all use (Navionics is even worse, according to OpenCPN documentation) versus paper or pilot books or ENC charts -- according to the OpenCPN documentation. With their "poor graphic representation in small scale charts of reefs,small islands and other dangers." That's the OpenCPN authors talking about the vector charts on your plotter, and on mine. Kind of what I have been talking about all this time.

So we can make a different chart choice, like some on here do -- namely paper. I don't know where to buy ENC charts, and I'm guessing the cost is prohibitive. Raster charts are immune to this problem since they only have a single layer, but bring their own problems. Might be worth trying just for planning purposes -- NV sell them for my cruising area, albeit at a quite high cost -- about 400 euros or nearly $500 just for Finnish waters.

Or we can try to use what we have -- the commercial vector charts used by 99% of cruisers -- in a better way.

In reading your messages, I still come away with the feeling that you're quick to criticize and suggest "upgrades," while not spending nearly as much time as you should learning all of OpenCPN's features that could accomplish what you are looking for.

If your concern is that less detailed charts are covering up the more detailed charts, there are multiple ways that you can prevent this. You could create separate chart groups for the more detailed charts, and only activate those. The less detailed ones could be activated at other times if you don't want the details.

Also, did you know that you can mouse-over the piano buttons in the status bar to see which chart they represent? Once you've found the less-detailed chart that is covering up the details that you want to see, just right-click on the piano button and select "hide this chart."

Raster charts are not "immune to this problem," since less detailed raster charts will cover up more detailed ones. If you want, this can be overcome by the same methods I mentioned in the previous two paragraphs.

I suggest that you give these things a try on your big-screen monitor and take some screen shots to show us the results. I have little doubt that you can filter your charts to see the details that you say you want. I do have my concerns that, once you succeed at doing this, the screen will be so cluttered with details that you won't be able to see much of anything.

[Dockhead]

Originally Posted by RhythmDoctor

In reading your messages, I still come away with the feeling that you're quick to criticize and suggest "upgrades," while not spending nearly as much time as you should learning all of OpenCPN's features that could accomplish what you are looking for.

If your concern is that less detailed charts are covering up the more detailed charts, there are multiple ways that you can prevent this. You could create separate chart groups for the more detailed charts, and only activate those. The less detailed ones could be activated at other times if you don't want the details.

Also, did you know that you can mouse-over the piano buttons in the status bar to see which chart they represent? Once you've found the less-detailed chart that is covering up the details that you want to see, just right-click on the piano button and select "hide this chart."

Raster charts are not "immune to this problem," since less detailed raster charts will cover up more detailed ones. If you want, this can be overcome by the same methods I mentioned in the previous two paragraphs.

I suggest that you give these things a try on your big-screen monitor and take some screen shots to show us the results. I have little doubt that you can filter your charts to see the details that you say you want. I do have my concerns that, once you succeed at doing this, the screen will be so cluttered with details that you won't be able to see much of anything.

I'm not criticizing! I'm a big, big fan of OpenCPN.

I'm struggling to get better results with electronic navigation, and I'm sharing ideas which be valid and useful, or not.

I certainly do not know everything this powerful program can do, and quite possibly there are some existing tools which could help which I simply don't know about. I was actually studying those features you wrote about this eveming. I can't use the separate scale buttons because they don't work with CM93 charts. Do they allow you to choose the chart scale independently from zoom level? And will the larger scale charts - if you zoom out beyond the usual for that scale - quilt together to cover the screen? Can you use the piano keys to override the automatic choice of chart scale? If so, these could be the answer to my prayers.

Another idea I had, maybe useful, maybe not - how about if you could split the screen into two parts at different scales and zoom levels, independently set by the user. On one side, you lay out your whole route, or a leg of it, at a zoom level which allows you to see the whole route - the "big picture". The other side you set at a zoom level which lets you see all the hazards and detail. As you hover the mouse over the zoomed out half of the screen, the zoomed in half pans to show that bit. Maybe with a box on the zoomed out part under the mouse cursor, showing you what is displayed on the zoomed in half? That would be a really powerful planning tool I think - giving you context and "big picture" orientation for the detailed view. What do you think?

[Dockhead]

Originally Posted by RhythmDoctor

In reading your messages, I still come away with the feeling that you're quick to criticize and suggest "upgrades," while not spending nearly as much time as you should learning all of OpenCPN's features that could accomplish what you are looking for.

If your concern is that less detailed charts are covering up the more detailed charts, there are multiple ways that you can prevent this. You could create separate chart groups for the more detailed charts, and only activate those. The less detailed ones could be activated at other times if you don't want the details.

Also, did you know that you can mouse-over the piano buttons in the status bar to see which chart they represent? Once you've found the less-detailed chart that is covering up the details that you want to see, just right-click on the piano button and select "hide this chart."

Raster charts are not "immune to this problem," since less detailed raster charts will cover up more detailed ones. If you want, this can be overcome by the same methods I mentioned in the previous two paragraphs.

I suggest that you give these things a try on your big-screen monitor and take some screen shots to show us the results. I have little doubt that you can filter your charts to see the details that you say you want. I do have my concerns that, once you succeed at doing this, the screen will be so cluttered with details that you won't be able to see much of anything.

And thanks very much for the specific tips - I'll try them when I have suitable charts.

Obviously regulating the detail so that you don't cross the line into harmful clutter is the whole point. But here one size doesn't fit all! You can pack an order (or orders) of magnitude more detail into a 32" 4k screen than you can into an 8" SVGA one! The "slider" is not enough, but maybe the tools you're talking about are.

[transmitterdan]

Originally Posted by Dockhead

Another idea I had, maybe useful, maybe not - how about if you could split the screen into two parts at different scales and zoom levels, independently set by the user. On one side, you lay out your whole route, or a leg of it, at a zoom level which allows you to see the whole route - the "big picture". The other side you set at a zoom level which lets you see all the hazards and detail. As you hover the mouse over the zoomed out half of the screen, the zoomed in half pans to show that bit. Maybe with a box on the zoomed out part under the mouse cursor, showing you what is displayed on the zoomed in half? That would be a really powerful planning tool I think - giving you context and "big picture" orientation for the detailed view. What do you think?

I think this is a pretty good idea. It would have to be well thought out to work seamlessly. A plugin could probably be created that would show the "overview" big picture. That's kind of how the Google Earth plugin works.

You can run two copies of OpenCPN but you have to do a bit if finagling to get it to work. On a dual monitor system you could have one copy on the wide view on one screen and the other copy with the zoomed in view. If you use the follow ship mode to control the scrolling based on your location they would track one another. But you couldn't pan one manually and have the other follow it so far as I know.

It would take some "magic" to get the NMEA data fed to both copies of the program and there are some other issues so this would not be for the faint of heart. But I think it can be done with available tools. ISTR someone else doing this a while back. Maybe one of the O experts will chime in.

[RhythmDoctor]

You have to answer these questions for yourself. You have a 4000-line (4x HD) monitor. I don't and I doubt many here do. So you need to try it, experiment with the different settings, and tell us what works. It should take you less time to try these things than it takes you to type out the questions. But afterwards, please take the time to type out the results.

As for split screen, you could install two separate portable mode installations and run them side-by-side in separate Windows. (I do this all the time on my tablets.) You can zoom in one side, and zoom out the other. Export your route in .gpx format, and import it on the other running instance. This will not do everything you want (pointing in one window won't bring up information in the other window), but while underway in follow mode both screens will automatically pan in the same way. This is a great way to do it if you have AIS, because you can see distant targets in the zoomed out window and nearby hazards in the zoomed in window. As a result, you spend your time sailing and not constantly zooming in and out on the tablet/computer. You can share NMEA data from one instance to the other by setting up a UDP network connection.

[seandepagnier]

Originally Posted by RhythmDoctor

Export your route in .gpx format, and import it on the other running instance.

Wouldn't it be nice if you didn't have to export and import?

I think this would be possible rather easily by having opencpn use some inter-process communication, but maybe it would be better to support multiple chart canvas within the same process because it would also allow sharing duplicated video memory, and a lot of duplicated ram buffers.

[downunder]

Originally Posted by Dockhead

That's what everybody says about the Baltic . . .


Patagonia is also high on my list. You should write up and post about your adventures down there.

There is a great book with drawings of most of the anchorages and most everything else needed for sailing Patagonia.

Patagonia and Tierra Del Fuego Nautical Gde 2nd Ed Hardcover – January 1, 2004 by Mariolina Rolfo & Giorgio Ardrizzi

[colemj]

Originally Posted by Dockhead

Sure, if you want to look at it that way -- it's the choice of ordinary vector charts like we all use (Navionics is even worse, according to OpenCPN documentation) versus paper or pilot books or ENC charts -- according to the OpenCPN documentation. With their "poor graphic representation in small scale charts of reefs,small islands and other dangers." That's the OpenCPN authors talking about the vector charts on your plotter, and on mine. Kind of what I have been talking about all this time.

So we can make a different chart choice, like some on here do -- namely paper. I don't know where to buy ENC charts, and I'm guessing the cost is prohibitive. Raster charts are immune to this problem since they only have a single layer, but bring their own problems. Might be worth trying just for planning purposes -- NV sell them for my cruising area, albeit at a quite high cost -- about 400 euros or nearly $500 just for Finnish waters.

Or we can try to use what we have -- the commercial vector charts used by 99% of cruisers -- in a better way.

Wait - ENC are vector charts. Typically in S57 or S63 format. I have many of them, and several countries produce and distribute them for free.

The "ordinary" CM93 charts you are talking about, and using, are illegally stolen ones that have not been updated in several years, and whose formatting does not give them the same functionality as ENC formats. That is not a statement on ethics - it is a statement on you projecting a problem from using the wrong tools. In other words, "I have a screwdriver so the nail is the problem".

Subtly sliding this problem over to chart plotters is Quixotic. This thread was about planning and everyone agrees that using a chart plotter for planning is not optimum for reasons that have little to do with the charts running on them. They never will be optimum because it is not their primary purpose.

Almost everyone will plan on something else more convenient and simply upload routes and waypoints to a plotter. Heck, this is the way it is done with PAPER charts - albeit much more cumbersomely and error-prone.

Vote with your wallet. Improving charting programs is always good, but attempting to bolt on functionality to overcome limitations on bad or incomplete datasets will lead to a mess.

Mark

[bcn]

Originally Posted by transmitterdan

I think this is a pretty good idea. It would have to be well thought out to work seamlessly. A plugin could probably be created that would show the "overview" big picture. That's kind of how the Google Earth plugin works.

You can run two copies of OpenCPN but you have to do a bit if finagling to get it to work. On a dual monitor system you could have one copy on the wide view on one screen and the other copy with the zoomed in view. If you use the follow ship mode to control the scrolling based on your location they would track one another. But you couldn't pan one manually and have the other follow it so far as I know.

It would take some "magic" to get the NMEA data fed to both copies of the program and there are some other issues so this would not be for the faint of heart. But I think it can be done with available tools. ISTR someone else doing this a while back. Maybe one of the O experts will chime in.

The feature request #1292 at Flyspray covers this.
You might want to issue a vote for it.....

Hubert

[jonasaberg]

Of course the captain is responsible for the navigation, but today it seems to be so much easier than it was 30 years ago. Then the charts was the accurate part of the system, and the position system the weak link with taking bearings, dead reckoning, astronomical navication etc. Today GPS has changed all this and it is the opposite. When the GPS works we usually know pretty well our position much better than the accuracy of the chart.

I am getting of target. My point is that charts and positioning are merely tools we use to travel safely at sea, and those tools in combination with good judgement help to plan and travel safely.

A route safety checker is just such a tool, no more and no less. It could support the navigator. It would not take away his responsibility to plan safely.

It is not needed always, but I agree with Dockhead, that it would a good support in some areas, such as the baltic sea archipelagos. I would still run through a planned route using the most detailed charts, keep an eye on the terrain and the the sea at helm.
But, I think it would be a good aid in the planning phase.
And the idea to put a fat red line, a cross or a marker to indicate obstacles along a route that can be seen on all charts regardless of magnification/zoom level seems to me like a good aid. (An aid, that do not take away the responsibility of the captain)

Just my opinion...

/Jonas

[bcn]

This is what an ECDIS is required to do:

(232/A11.3.4) An indication is required if the mariner plans a route across an own ship’s safety contour.
(232/A11.3.5) An indication shall be given if the mariner plans a route closer than a userspecified distance from the boundary of a prohibited area or a geographic area for which special conditions exist (see Annex C). An indication shall also be given if the mariner plans a route closer than a user-specified distance from a point object, such as a fixed or floating aid to navigation or isolated danger. This distance limit may be the same applied to the proximity of all dangers and identical to the distance limit applied for approaching the boundary of a prohibited area, area with special conditions.
(232/A11.3.6) It shall be possible for the mariner to specify a cross track limit of deviation from the planned route at which an automatic off-track alarm shall be activated.

The same applies later for Route Monitoring, being underway.

The indication can be a symbol on the plotted route and/or a listing of alerts like "123,5 nm - entering Traffic Seperation Scheme"

Just to add some ideas.......

Hubert

[jonasaberg]

Originally Posted by bcn

...The indication can be a symbol on the plotted route ...

Yes, this is what I interpreted that Dockhead was requesting. This would be neat to have.

[Dockhead]

So, I've bought a set of raster charts covering UK, Ireland, Belgium, and Holland from Visitmyharbour.com, whose little office is just a few steps from my boat's winter home in Cowes.

I've been playing with them, and with the "piano key" controls in OpenCPN.

Here are my conclusions:

1. Raster charts are a totally different ball of wax from vector charts. This is my first experience with them. They are absolutely lovely for someone who is homesick for paper navigation, as that's what they are, complete with all the legends and everything you would expect from a paper chart.

2. The "zoom problem" does not really exist with these charts. That is because decluttering is not done the way it's done with vector charts -- there's no decluttering at all, in fact, other than switching from one chart to another (corresponding exactly to the paper charts). The "Hide this Chart" control is superb -- you can get rid of the zoomed out chart and see the zoomed in charts in geographic relationship to each other, even if they are not continguous. But this is rarely needed, because in general, you have the same possibilities you have with paper -- you just choose the same chart you would be using for paper planning, and you have all the same details.

3. However, the size and resolution of the monitor enormously influences how well this works. My nav table 23" 1080 line monitor is not all that fantastic -- far less detail than a paper chart. Not all that fantastic, but usable. My bulkhead 4000 line monitor, on the other hand, gives you just about the same picture you would get from paper. So it may be that raster charts and better and better monitors may really replace paper completely, and I think it's already damned good.

4. These raster charts have a lot of disadvantages compared to vector charts, however. You lose the seamless view with seamless zooming. They would not be very good for chart plotting, say from the helm, as opposed to planning.

5. Anytime you poke into another corner of OpenCPN, you see how incredibly powerful and intelligently designed it is. Raster charts and piano keys give you tools I never imagined you could could have with electronic charting. It's as if you can flip through a large pile of perfect paper charts with the click of the mouse. This is just awesome. And the advantage of planning on this compared to paper will be, as someone above mentioned, that you can easily transfer your routes to your plotter.

6. The "zoom problem" is still a real problem, however, because 90% or more of cruisers use commercial vector charts, or CM93. Since the problem really boils down to the method of decluttering used, surely this could be solved with more control over the decluttering process. To restate one aspect of the problem, maybe more clearly now -- the standard scheme of decluttering of vector charts is designed for small, low res screens. It knocks out too much detail too fast, in order to be able to use OpenCPN for planning passages in complicated water, on a larger, higher res screen -- the capabilities of the monitor is wasted. The "Chart Zoom/Scale Weighting" slider exactly addresses this issue, but it doesn't go nearly as far as we need. Is it possible to extend it?

7. The other aspect of the zoom problem is the disappearance of hazards when using large scale views, as discussed in the OpenCPN manual*. I think showing some kind of proxy for hazards as we've been discussing would be just terrific, if it's not too hard to program. Just some kind of symbol or blotch or shading which indicates there are problems which need to be looked at in that area. The makers of commercial chart plotters should think about this too, IMHO.

8. Certain kinds of details don't need to be suppressed at all -- like TSS's. These are just lines, so no reason in the world not to represent them in all scales. This is just wrong. This may be inherent to the particular vector cartography; don't know if anything can be done about it inside of OpenCPN.

9. Some ability to split the screen, put a little box in the large-scale view which can be moved with your mouse, and which shows what is being represented in the small-scale view, would be an incredibly useful tool for planning with vector charts (maybe with raster charts too).



* From the OpenCPN manual:

"Using CM93 in OpenCPN
It all starts with passage planning. The bottom line is: Don't trust CM93. Always check with other reliable sources, meaning, for example, Raster charts (paper charts) Pilot Books, or ENC charts, not another privately issued vector chart, with similar problems ( for example Navionics).

"Doing the best you can with OpenCPN and only CM93 available.
For passages including small scale CM93 charts (A or Z scale):
Create a route that you plan to follow.
Switch to Single chart mode. Short Key "Q".
Avtivate chart outlines.Short Key "O".
"Fly" along the route, making sure you are zoomed in to a factor of at least 2.5 x.
Available charts should now be outlined in magenta.
Drop suitable marks documenting these charts, and the dangers they represent, for later reference."

"Doing the best you can" isn't really good enough -- surely we can provide somewhat better tools. All the detail is present in CM93 and other commercial vector cartography -- this is definitely not a question of "inferior or incomplete data sets" as someone above claimed. It's just a question of how it's presented -- how the decluttering scheme is implemented.

[Dockhead]

Originally Posted by jonasaberg

Yes, this is what I interpreted that Dockhead was requesting. This would be neat to have.

Yes! Some kind of proxy -- a symbol, shading, something to give a clue that there's something which requires a closer look.

[Dockhead]

Originally Posted by RhythmDoctor

. . .

If your concern is that less detailed charts are covering up the more detailed charts, there are multiple ways that you can prevent this. You could create separate chart groups for the more detailed charts, and only activate those. The less detailed ones could be activated at other times if you don't want the details.

Also, did you know that you can mouse-over the piano buttons in the status bar to see which chart they represent? Once you've found the less-detailed chart that is covering up the details that you want to see, just right-click on the piano button and select "hide this chart."

Raster charts are not "immune to this problem," since less detailed raster charts will cover up more detailed ones. If you want, this can be overcome by the same methods I mentioned in the previous two paragraphs.

I suggest that you give these things a try on your big-screen monitor and take some screen shots to show us the results. I have little doubt that you can filter your charts to see the details that you say you want. I do have my concerns that, once you succeed at doing this, the screen will be so cluttered with details that you won't be able to see much of anything.

Thanks ever so much for these extremely useful tips

I've done all this and it works as advertised. Fantastic tools.

I have only tried the piano keys with raster charts, as they don't work with CM93. Hovering over the piano keys has yet another fantastic purpose, when you have raster charts -- you know what charts are available, so you can choose which one to look at. This is useful for far more than solving the zoom problem -- it's like having a big pile of real charts on your nav table which come instantly to view by hovering the mouse, rather than having to physically flip through them. It is an improved paper chart experience

With the raster charts which I have (visitmyharbour.com), the piano keys are not much needed for planning, as you just choose the chart you would be using anyway, if you had paper. I did successfully use them, and "Hide this Chart", to show me detailed views at two ends of a passage -- very useful, as they are shown in correct geographical relation to each other. You will want a bigger and bigger and higher res monitor to make this work really well. But with these raster charts, I think mostly one will just be using that chart which you would be using in paper -- far less detail is suppressed, than with the vector charts.