Trouble with symbols

[Littlechay]

I see several symbols on CM93 charts that do not display properly.

I have raised the tidal current direction arrows issue before but also notice that underwater rock UWROC symbols and certain wreck symbols are affected too.

The tidal current symbols do display but the scale relative to the rest of the chart is wrong and they are overlaid with a "caution area" symbol that should not appear.

See attached screenshots.

If anybody else want's to add more symbols to this thread please do so that the developers can look into it. I have noticed others in passing but don't have examples to hand.

If you want to check this out the position is shown by cursor position in the status bar of the screen shot.

[did-g]

Originally Posted by Littlechay

I see several symbols on CM93 charts that do not display properly.

I have raised the tidal current direction arrows issue before but also notice that underwater rock UWROC symbols and certain wreck symbols are affected too.

The tidal current symbols do display but the scale relative to the rest of the chart is wrong and they are overlaid with a "caution area" symbol that should not appear.

See attached screenshots.

If anybody else want's to add more symbols to this thread please do so that the developers can look into it. I have noticed others in passing but don't have examples to hand.

If you want to check this out the position is shown by cursor position in the status bar of the screen shot.

Hi,

I have to double check but for me the magenta symbol (isolated danger) is right for underwater rocks with unknown depth in safe water . What would you expect?


On the other hand there's an issue with rocks or wrecks within the depth of the surrounding area (ie when area high level is safe ). NOAA charts but they seem to replace them with non dangerous kind.

[Littlechay]

Originally Posted by did-g

Hi,

I have to double check but for me the magenta symbol (isolated danger) is right for underwater rocks with unknown depth in safe water . What would you expect?.

It's not an isolated danger symbol though it is a rock awash which would be something like an asterisk symbol on or a + with dots in each quadrant. My other plotter software shows it correctly (see attached).

Right clicking shows it as rock awash.

That magenta symbol seems to be used in OCPN as a default for symbols that are not in the decode table.

[belle-isle]

I also agree with this issue. It had long annoyed me but I never got around to reporting it.

In addition, and I may be mistaken about this, but I was under the impression that the magenta layer on a chart was for non-essential features, which instinctively leads me to disregard it in a first quick scan of the chart. In fact when the chart is referring to a danger, I got caught several times at not having properly realized that a rock was there.

I agree that either another (black) symbol, or better the correct one, would be better.


Sent from my iPad using Cruisers Sailing Forum

[did-g]

Originally Posted by Littlechay

It's not an isolated danger symbol though it is a rock awash which would be something like an asterisk symbol on or a + with dots in each quadrant. My other plotter software shows it correctly (see attached).

Right clicking shows it as rock awash.

That magenta symbol seems to be used in OCPN as a default for symbols that are not in the decode table.

On your plotter the rock is not in the safe water area (outside bold line).

In ocpn change the safety depth setting to 20 meters and you get a '*' symbol.

For testing if you can on your plotter change this setting to 10 or 5.

[Littlechay]

Originally Posted by did-g

On your plotter the rock is not in the safe water area (outside bold line).

In ocpn change the safety depth setting to 20 meters and you get a '*' symbol.

For testing if you can on your plotter change this setting to 10 or 5.

Whatever the safety depth the symbol should still be a rock and it is on other systems whatever the safety depth. I've just checked on TZ and I get the correct rock symbol whatever the safety depth. Same behaviour on other systems that I have used.

If you look at my second example I have to set the safety depth to 50m, in OCPN, to see the symbols.

If this is intended behaviour I don't believe that it is correct behaviour. It is certainly unusual.

[nohal]

Originally Posted by Littlechay

Whatever the safety depth the symbol should still be a rock and it is on other systems whatever the safety depth. I've just checked on TZ and I get the correct rock symbol whatever the safety depth. Same behaviour on other systems that I have used.

If you look at my second example I have to set the safety depth to 50m, in OCPN, to see the symbols.

If this is intended behaviour I don't believe that it is correct behaviour. It is certainly unusual.

If I remember correctly, this has been already studied and OpenCPN's behavior is per ECDIS standard, which, although it might look illogical and wrong to you, requires the feature display to be changed to the magenta symbol for caution area for rocks of unknown depth in safe water.

Pavel

[did-g]

Originally Posted by Littlechay

Whatever the safety depth the symbol should still be a rock and it is on other systems whatever the safety depth. I've just checked on TZ and I get the correct rock symbol whatever the safety depth. Same behaviour on other systems that I have used.

If you look at my second example I have to set the safety depth to 50m, in OCPN, to see the symbols.

If this is intended behaviour I don't believe that it is correct behaviour. It is certainly unusual.

It's the intended behaviour.

Maybe there's new specifications for conditional symbology in this case but they aren't free (500 USD) or others software do whatever they think is better.

OCPN follows (ok tries to follow) IHO ECDIS version 3.2 presentation library and in my understanding it's the behaviour requested by UDWHAZ03 procedure page 176 in the pslb03_02.pdf I have.

Is it the right thing do to? Not my call.

[Littlechay]

Originally Posted by nohal

If I remember correctly, this has been already studied and OpenCPN's behavior is per ECDIS standard, which, although it might look illogical and wrong to you, requires the feature display to be changed to the magenta symbol for caution area for rocks of unknown depth in safe water.

Pavel

The Billy Rock, my example 1 is not and unknown depth it is a awash and shows as such if you right click on it.

There are plenty of other rocks in the area that don't morph into magenta blobs on OCPN or any other electronic chart system that I have used.

Surely it is not the correct behaviour for wrecks?

And the tidal current arrows? They do show but no ebb flood indication and the scale is wrong.

[did-g]

Originally Posted by Littlechay

The Billy Rock, my example 1 is not and unknown depth it is a awash and shows as such if you right click on it.

There are plenty of other rocks in the area that don't morph into magenta blobs on OCPN or any other electronic chart system that I have used.

Surely it is not the correct behaviour for wrecks?

And the tidal current arrows? They do show but no ebb flood indication and the scale is wrong.

The exact wording is:

Obstructions or isolated underwater dangers of depths less than the safety
contour which lie within the safe waters defined by the safety contour are
to be presented by a specific isolated danger symbol as hazardous objects
and put in IMO category DISPLAYBASE (see (3), App.2, 1.3). This task
is performed by this conditional symbology procedure.

Same for wrecks

Wrecks of depths less than the safety contour which lie within the safe waters
defined by the safety contour are to be presented by a specific isolated
danger symbol and put in IMO category DISPLAYBASE (see (3), App.2,
1.3). This task is performed by the sub-procedure "UDWHAZ03" which is
called by this symbology procedure.

But it's an old spec maybe we can figure out a way and buy the latest? No ideas what is IHO policies.

I'll try to have a look at the current arrows.

[Littlechay]

Originally Posted by did-g

The exact wording is:

Same for wrecks

But it's an old spec maybe we can figure out a way and buy the latest? No ideas what is IHO policies.

I'll try to have a look at the current arrows.

I see the same symbol in the latest version of Chart number 1 so it is certainly valid in the US. I don't have an up to date UK Admiralty equivalent 5011, but their quick guide to ECDIS symbols does show it.

I thought it was just an OCPN thing for an object it didn't understand up until you guys enlightened me; based on the fact that I have only seen it in a few places in OCPN and not on any other plotters.

Edit: I still don't get the logic. Some rock with seemingly identical characteristics don't get the magenta symbol. Same for example there is wreck with a swept depth of 15m in area of otherwise around 25m. If I change the safety depth to 20m that should change to the magenta symbol according to the logic stated in the Admiralty guide ("Generic isolated danger symbol – with less depth than user-selected safety contour or where the depth is unknown"). So unknown depth seems to work sometimes but object with know depth but otherwise satisfying the criteria are not showing.... still confused.

What defines an isolated danger?
end of edit.

You live and learn.

Thanks for taking a look at the tidal arrows. I have raised this before and there was some improvement a couple of releases back. However there is still something amiss .