S63 charts - overzoom

[jongough]

Dave,
I have compiled a version up and installed it on my navigation PC to see what it is like with the S63 charts. It works as advertised. However, on the chart I gave as an example I get one overzoom step showing a faded background then the next overzoom goes to the base blue background. Is it possible to add a few more steps in there so that I get a slow (i.e. >= 4 zoom steps) fade from normal to background blue?

Thanks
Jon

Originally Posted by bdbcat

Guys...

I have prototyped a chart fade, or "fogging" effect on excessive overzoom. It is a linear fade, starting at OZ=10, and the chart detail is completely gone when OZ=30. The screen assumes the blue color of the worl background chart. Zooming can continue for all (now invisible) chart types up until the onscreen scale is about 1/600, depending upon latitude for mercator charts. At 1/600, 2 metres (best GPS accuracy) is about 3 mm, or a bit more than 1/8 inch on screen.

Look for this on github tomorrow, and in the next Beta coming in a few days.

Dave

[bdbcat]

jon...

Try options->Smoothzoom

Dave

[tom_BigSpeedy]

Sorry guys, this fading out is an absolute no-go for me.
The reason is quite simple :
My laptop is installed under deck on the chart table, and when sitting outside at the tiller, I have at least 3m distance to the 14'' screen.
I simply don't see anything with a 16x or 20x overzoom...
And removig the contrast the more you zoom makes it even worse !
And I'm not even talking about sunlight shining through the windows/hatch ... (no I don't have curtains, and I won't install, she's a racer !)
Full 40x overzoom is simply damned useful in a harbour entrance/ canal between sea marks when you have 2 kts of current from the side.


It's still the responsibility of the navigator, to check what he's doing. And if someone's dumb enough to trust a chart with 40x overzoom, then he should really learn it the hard way. Next time he'll know better. He should have learnt anyway making his sailing license ...

But actually I really wonder that we now start teaching navigators ...
On the one hand, we're removing the whole chart, because it might be dangerous, but on the other hand what about our responsibility, if someone really needs the overzoom in a dangerous situation for whatever reason and we remove his charts with forefinger up : "We know better, this might be a problem for you ...!"

At least I request an option to turn fading completely off, otherwise I'll fork ...
Thomas

[bcn]

From the 3.3.2302 thread:

The current alpha test code has what we might call an "expert" mode. There is a config file setting that disables OZ fogging, but no check box in the runtime options dialog.

So, folks willing to edit the config file can have their high overzoom with charts fully visible.

Default (ie "in-expert") users will get fogging.

Dave

[tom_BigSpeedy]

I can live with the ini file solution, but I still don't get.

Why fade out to 0 (Zero, Nada, Niente), and not stop at e.g. 60% ???
That should be a clear "hint" to any ID10T navigator ...

Thomas

[bdbcat]

Thomas...

I hear you.

But I encourage you to read the technical detail on chart geo features and compilation scale.

"Full 40x overzoom is simply damned useful in a harbour entrance/ canal between sea marks when you have 2 kts of current from the side."

Sea marks are one thing. Intended station is well known, from the light list. That is, if it's on station...

But what about jetties? Fixed geo features have a positional accuracy that is surpisingly low, even with modern charts. Add to that the GPS error factor, a bit of fog, and you will see the trouble.

We don't intend to teach navigation here. But we intend that what OCPN says, it believes to be true.

Anyway, fork away if you like. We have lots of technically savvy users running their own forks, for a variety of reasons. The "official" fork will continue to support the mainstream "install-and-run" population.

Thanks
Dave

[bdbcat]

Folks...

Interesting read...
http://www.chersoft.co.uk/Resources%...sterVector.pdf

Dave

[jongough]

Dave,
Using the +/- keys this changes the steps from 3 to 8, using the mouse wheel it does not change it (on this chart anyway). I can live with that. Thanks for the info.

Jon

Originally Posted by bdbcat

jon...

Try options->Smoothzoom

Dave

[Viking Sailor]

Originally Posted by bdbcat

Folks...

Interesting read...
http://www.chersoft.co.uk/Resources%...sterVector.pdf

Dave

A quote from the above referenced PDF: "So, zooming is not an advantage of vector charts over raster charts. It is simply a prerequisite for usable vector charts."

The learning curve for how to use zooming is not so great as to be a problem for anyone capable of piloting a vessel.

Thus, I vote for having unlimited zooming.

[Wanderlust]

I had been reading this thread because I plan to get S63 in a few months, but crippling the capabilities would be a real concern for me. It's great that there is at least an INI file solution.

I understand the benefits of higlighting that the chart is zoomed beyond design and like that feature. But please highlight that fact, not cripple it. Does the INI setting stop only the fogging, but not the warning?

[tom_BigSpeedy]

Dave,

there is so many different types of charts around, and you're crippling them all togehter in one shot. I am constantly adjusting the CM93.2, so they fit to reality ... more or less.
Maybe you should replace the "OVERZOOM" with something more meaningful, like "DEGRADED ACCURACY", or even better, show ACCURACY level in m, ft, nm, ...

I would absolutely follow with reading DOP/accuracy from the GPS, and then placing an "accuracy circle" around ownship ...
But removing the whole chart ... I don't see it.

As the others already mentioned : I also use extreme overzoom for planning, or simply finding exaclty the same anchor spot in that one bay by following an old track, especially at night :
Quite useful when you know that there is sand between the rocks.
This is all gone now, w/o manipulation of the ini file.
You always stated : O is a program from (real) sailor, for sailors.
Now we're at a point where I have to say: No, it's not anymore, too many armchairs involved.

But O is your baby, I'm out of it now.
Good luck.

This is my last post on this topic.

Regards,

Thomas

[bcn]

Thomas,

would you mind to have a look at today's build?
Should calm your concerns....

Hubert

[cagney]

Here is a sad illustration to the navigation dangers talked about above.

The Volvo Ocean racer "Vestas" earlier this evening went aground near South Island on Cargagos Carajos Shoals (Mauritius).
More here Volvo Ocean Race / Team Vestas Wind statement | Volvo Ocean Race 2014-2015



They are said to be 1.5 km from South Island. In the illustration above, the measured distance, is just a guess.

All other yachts in the race passed the Shoals well to the west.
The chart datum is WGS 84, and ..... the survey is
British Admiralty in 1846

So..... how could this happen?

Thomas

PS Anyone using CM93 for navigation should have a look att Cargagos Carajos.

[bcn]

Your cursor position in Google Earth....

[Viking Sailor]

This of course has nothing to do with overzoom.

This is a result of plotting a WGS84 corrected GPS position on a chart based on a locally referenced 1846 survey. The error will be the same whether the position is plotted on a paper or an electronic chart.

Google Earth photos are referenced to WGS84 and can be used to correct locally referenced charts. OpenCPN provides a method to correct CM93 cells by manually applying a set of X, Y offsets. Additionally, phiggins, and yacthvallhala provide software and procedures to assist in making these corrections. (http://www.cruisersforum.com/forums/...ml#post1686331)