The Electronic Charting "Zoom Problem"

[Dockhead]

Originally Posted by bcn

Dockhead,

as the information about hazards is available from the vector charts even if those are not visible/not shown a "route checker" which uses this information would be a feature I would like to see in a future version.

In the planning stage and as "hazard 2nm ahead" pop-up option when underway.
And this using the safety contour defined for the vessel or that voyage.

No cluttering of the display and using the existing information.

Hubert

I think that both of these features would be extremely useful. Wish we could have the first of these on our regular plotters, too.

Route checking is fine, but it's no substitute for being able to see significant detail in the first place. That's because just guessing about where safe water is, does not always give you enough information to plot the route in the first place. This is particularly true in very complex water. You need to be able to see it.

[rgleason]

Relevant to discussion:

http://www.cruisersforum.com/forums/...ml#post1760312

FS#1717 : Dangerous rocks are hidden in CM93 when Standard display is selected

See Thomas's comment at below the forum post.

[transmitterdan]

Even if Costa Concordia crew were mislead by their chart plotter that cannot even be close to the proximate cause of their calamity nor would I accept that it is part of the chain of errors leading up to the event. And I doubt that is what an honest assessment of the events leading up to the rock encounter would conclude. I would want to know if that note in the report was just someone with an axe to grind. Even report writers are not infallible. The electronic charts I recall from that time when set to the zoom level they should have been using made the rock they hit easily visible.

But let's step back and use logic for a minute (I know this is the internet where logic is a foreign concept) and think about the premise of this thread. The premise is that some unknown cartographer in some unknown office is capable of evaluating every hazard that could potentially endanger every vessel type. Then they are able to magically bring every one of these hazards to the attention of every navigator by their mystical power of pen and ink on paper regardless of the zoom level that displays the image. Furthermore, digital vector charts are incapable of achieving anything resembling this magical feat.

[Dockhead]

Originally Posted by transmitterdan

Even if Costa Concordia crew were mislead by their chart plotter that cannot even be close to the proximate cause of their calamity nor would I accept that it is part of the chain of errors leading up to the event. And I doubt that is what an honest assessment of the events leading up to the rock encounter would conclude. I would want to know if that note in the report was just someone with an axe to grind. Even report writers are not infallible. The electronic charts I recall from that time when set to the zoom level they should have been using made the rock they hit easily visible.

But let's step back and use logic for a minute (I know this is the internet where logic is a foreign concept) and think about the premise of this thread. The premise is that some unknown cartographer in some unknown office is capable of evaluating every hazard that could potentially endanger every vessel type. Then they are able to magically bring every one of these hazards to the attention of every navigator by their mystical power of pen and ink on paper regardless of the zoom level that displays the image. Furthermore, digital vector charts are incapable of achieving anything resembling this magical feat.

Well, first of all, no one said the Costa Concordia accident was principally caused by the ECDIS. If you read the linked article, which I recommend, you will find an excellent analysis of the chain of errors which were made. The display of detail was not a principle cause, but did fit in with and aggravate the other errors, and so the nature of vector charting made its own minor contribution. It's interesting and relevant.

Second -- no one said that "some unknown cartographer in some unknown office is capable of evaluating every hazard that could potentially endanger every vessel type" -- good grief! Where did you get that? What has been said by a couple of very knowledgeable people, including our own Rhythm Doctor, and the author of the Concordia article, is that the data displayed on a raster (or paper) chart is chosen by a professional in every given case for every given chart, not mechanistically by a computer program. The result is a much more informative display -- see Post 112 above by Rhythm Doctor. No one said that this is a panacea or covers every possible hazard -- it just makes any given scale more intelligent and useful. That's because every scale -- every zoom level -- of a raster chart is an individually crafted chart in itself, not a computer generated zoom level.

The downside, however, is that with raster or paper, you have far fewer zoom levels and a much more awkward transition between those far fewer levels. So for small and/or low res displays, and for plotting underway, raster charts are much less useful than vector ones, which is why vector charts are exclusively sold with commercial plotters. Vector charts zoom and pan seamlessly, unlike raster charts. That view is just what you want at the helm.

I would not think this would be so controversial. Also no one is saying that it's impossible to plan with vector charts. We're talking about relative degrees of ease and power, not absolute differences.

[rgleason]

Checking the route entered very carefully at appropriate scale is essential, quite obviously. A late minute change in route deserves the same level of attention. Control and use of the charts are a skill which must be developed, and there are improvements and tools which can help us. However there are risks of all kinds which we need to access and determine with our heads up. No computer program is going to be able to make those decisions. It can help, and we can make it a better tool, but in the end we call the shots..




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[Dockhead]

Originally Posted by rgleason

Checking the route entered very carefully at appropriate scale is essential, quite obviously. A late minute change in route deserves the same level of attention. Control and use of the charts are a skill which must be developed, and there are improvements and tools which can help us. However there are risks of all kinds which we need to access and determine with our heads up. No computer program is going to be able to make those decisions. It can help, and we can make it a better tool, but in the end we call the shots..

I totally agree. Just that checking the route is a different phase of the process, from the one we're talking about here, which is the initial planning phase.

A tool for route-checking sounds like a good idea, but I have never really suffered from the lack of one. I always check manually -- very easy to do with paper, all the more since that's how I was taught to do it. It's not fatally hard to do on a plotter, either -- just zoom in to the scale necessary to get all the hazards, and pan through the route. A bit tedious, but it works. It's really important to it every time -- even in familiar waters. A bet a lot of sailors often let it slide. I was taught, decades ago, to do this very, very systematically -- on the theory that "you are what you habitually do."

This is a completely different problem, from the problem of route planning in the first place, where I have not been able to get a satisfactory result with plotters; hence the original post.

[rgleason]

Sorry. It is a long thread. You suggest a new tool in the first post. Perhaps a plugin which uses boat data, minimum depths, clearances etc and a start point and end point and then tell it to make a route.
This sounds like weather-routing plugin with a slightly different emphasis. Wx has land avoidance but not as sophisticated as needed. Also needs other constraints like depth

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[Dockhead]

Originally Posted by rgleason

Sorry. It is a long thread. You suggest a new tool in the first post. Perhaps a plugin which uses boat data, minimum depths, clearances etc and a start point and end point and then tell it to make a route.
This sounds like weather-routing plugin with a slightly different emphasis. Wx has land avoidance but not as sophisticated as needed. Also needs other constraints like depth

Yes, my views evolved under the influence of the very useful suggestions of a number of knowledgeable people.

What I was suggesting was a way to control the display of detail at different zoom levels. As it turns out, OpenCPN already has such a tool. I learned to use it. It turns out, that it doesn't work that well -- it seems to be an inherent limitation of vector charts.

So now I've scaled back that suggestion, to something someone along the way during the thread suggested - that we should have at least some configurable symbols to show hazards (as we define them) along the way, in zoomed-out vector charts.

Someone else suggested that raster charts will be much better for planning. I had never used electronic raster carts. I bought a set (UK, Belgium, Holland) and learned to use them, plus some cool tools (the "piano keys") in OpenCPN which you can use to manipulate them. And I came to see the wisdom in this suggestion.

Now YOU have suggested that we should have some pop-up warning when we're navigating towards some hazard. That's already a rather different conversation, but I think it's a great idea.

[colemj]

Originally Posted by Dockhead

Now YOU have suggested that we should have some pop-up warning when we're navigating towards some hazard. That's already a rather different conversation, but I think it's a great idea.

Rose Point's Coastal Explorer not only warns you of obstacles while planning routes, but also warns you while navigating them. You can even have it speak to you in case you aren't looking.

Mark

[Dockhead]

Originally Posted by colemj

Rose Point's Coastal Explorer not only warns you of obstacles while planning routes, but also warns you while navigating them. You can even have it speak to you in case you aren't looking.

Mark

I heard that -- maybe from you. Sounds excellent.

[bcn]

Those are features from ECDIS requirements.

Some weeks ago:
http://www.cruisersforum.com/forums/...ml#post1721087

Handy tools that by any means will not avoid that one will have to check the charts in detail in a given moment. Plus eyeballing...

[rgleason]

Agreed to much of the above. Funny how words gwt in the way Dockhead. I intended wx route as a planning tool with hard avoidance.

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[rgleason]

Need to clarify. Sean is the author of wx routing. Wxrouting does have land avoidance based on the gsshs

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[seandepagnier]

It is very high on my priority list to expose depth soundings (and overhead clearance) to opencpn plugins. This will allow a future plugin to check routes (comparing soundings) and determine the closest danger, and also compare tides to give appropriate times for passing etc..

This is not going to work if the chart is inaccurate or lacks in detail.

Another option is combining google imagery with other charts to give a more accurate chart. Possibly image recognition can also check for shallow water, but often small clouds can be deceiving as well as boats anchored on the imagery that moved.

[seandepagnier]

It is very high on my priority list to expose depth soundings (and overhead clearance) to opencpn plugins. This will allow a future plugin to check routes (comparing soundings) and determine the closest danger, and also compare tides to give appropriate times for passing etc..

This is not going to work if the chart is inaccurate or lacks in detail.

Another option is combining google imagery with other charts to give a more accurate chart. Possibly image recognition can also check for shallow water, but often small clouds can be deceiving as well as boats anchored on the imagery that moved.