nv-charts Plugin

[decnet]

Hi,

I have a problem with CPN. All charts are vertical (see picture). What am I doing wrong?
System: WinXP
CPN: 3.1.1224.
nv-charts Plugin: 1.3




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[Gilletarom]

Hello,

I can not explain. All I can say is that I have no problem with 3.1.1328.

B.R. Gilletarom

[hwecken]

I do also have no problems with nv charts in 3.1.1328.
but i do not own the inland charts where you showed the problem
do you have this problem also in a chart of the baltic or north sea charts ?
Hartmut

[decnet]

I´ve inland charts only. But I´ve the same problem with all other 3.x versions.
With the Chart Navigator Lite is the image o.k..

[Gilletarom]

Hello Decnet,

Originally Posted by decnet

I´ve inland charts only. But I´ve the same problem with all other 3.x versions.
With the Chart Navigator Lite is the image o.k..

What are exactly the reference charts ?
Have you asked NV-Chart about your problem ? They are highly reactive
B.R. Gilletarom

[cagney]

The real question here seems to be: Does the OpenCPN nv-chart plugin work properly with skewed charts?
Anyone able to test this ?

Thomas

[Gilletarom]

For test, it is necessary that we have these charts. So, I repeat : "What are exactly the reference charts ?"
Gilletarom

[decnet]

@Thomas: I think that is the question.

@ Gilletarom: I have these charts: NV. Binnenband 1, Berlin & Märkische Gewässer - NV. Verlag DE

@ all:

idea: The charts in the view are not north oriented, only vertically. If all detail charts are north oriented, then everything is correct. Please, can someone check this?

[bdbcat]

decnet...

It seems that the largest scale chart in your image above is skewed, not north up. I have never seen a skewed nv-verlag chart, so far.

OpenCPN will not try to quilt skewed charts, and if you select a skewed chart in the chart bar, it will temporarily switch to single-chart, unskewed mode.

The problem here is that OpenCPN does not recognize that the selected chart is skewed.

I cannot easily purchase/download the indicated nv-Verlag chart from my current location for testing. However, in order to make progress most quickly, perhaps you could:

1. find and open in Wordpad the chart showing the difficulty
2. Cut and paste the top few lines of the chart into an attachment to this thread. It will look something like:

!Copyright 2003, Maptech Inc.  All Rights Reserved.
VER/2.00
BSB/NA=Stralsund Dänholm,NU=HLS39_1C,RA=1799,1182,DU=254
KNP/SC=4000,GD=WGS72,PR=MERCATOR,PP=54.31,PI=0.100,SP=,SK=0.0000000
    TA=90.0000000,UN=METERS,SD=MEAN SEA LEVEL BALTIC,DX=0.40,DY=0.40

Note the data

SK=0.00000

What we are looking for is a non-zero number here on the chart that does not display properly.

Compare carefully the chart name to be sure you are looking at the same chart in Wordpad and on OpenCPN screen.

This will give a starting point to study the problem.

Thanks
Dave

[Gilletarom]

Originally Posted by decnet

@ Gilletarom: I have these charts: NV. Binnenband 1, Berlin & Märkische Gewässer - NV. Verlag DE

Sorry. I do not have this chart and so I cannot try.
Have you asked Nv-Chart about this chart?

[decnet]

Hi bdbcat,

this is the header:

!Copyright 2011, Nautische Veröffentlichung Vlg mbH. All Rights Reserved.
VER/3.0
BSB/NA=Teupitzer Gewässer - TPG 1
NU=TPG_1,RA=2711,7811,DU=508
KNP/SC=35000,GD=WGS84,PR=MERCATOR,PP=52.160000,PI=1,SP =,SK=0.0000000
TA=90,UN=UN=METER,SD=Mittelwasser,DX=1.75,DY=1.75
KNQ/EC=WE,GD=WGE,VC=UNKNOWN,SC=MLLW,PC=MC,P1=UNKNOWN,P 2=52.160000
P3=NOT_APPLICABLE,P4=NOT_APPLICABLE,GC=NOT_APPLICA BLE,RM=POLYNOMIAL
CED/SE=2012,RE=1,ED=01/05/2012
OST/1
IFM/6
RGB/1,0,0,0
RGB/2,255,255,255
RGB/3,226,10,22
RGB/4,250,201,216
RGB/5,168,224,248
RGB/6,95,200,241
RGB/7,0,129,49
RGB/8,255,241,0
RGB/9,255,249,162
RGB/10,112,111,110
RGB/11,253,252,228
RGB/12,181,180,180
RGB/13,0,122,190
RGB/14,241,176,206
RGB/15,168,211,171
RGB/16,255,243,122
RGB/17,226,191,160
RGB/18,242,142,0
RGB/19,229,0,131
RGB/20,255,238,0
RGB/21,92,91,96
RGB/22,192,226,202
RGB/23,96,100,40
RGB/24,100,4,7
RGB/25,100,24,47
RGB/26,239,135,103
RGB/27,100,42,27
RGB/28,100,81,70
RGB/29,63,100,91
RGB/30,57,100,100
RGB/31,56,80,100
RGB/32,50,58,100
RGB/33,55,48,100
RGB/34,153,109,138
RGB/35,233,93,96
RGB/36,233,223,0
RGB/37,58,236,171
REF/1,0,7811,52.141211,13.560803
REF/2,903,7811,52.130430,13.575886
REF/3,1807,7811,52.119634,13.590986
REF/4,2711,7811,52.108836,13.606085
REF/5,0,5208,52.167846,13.611422
REF/6,903,5208,52.157071,13.626504
REF/7,1807,5208,52.146282,13.641604
REF/8,2711,5208,52.135490,13.656704
REF/9,0,2604,52.194475,13.662059
REF/10,903,2604,52.183707,13.677142
REF/11,1807,2604,52.172924,13.692242
REF/12,2711,2604,52.162138,13.707341
REF/13,0,0,52.221088,13.712697
REF/14,903,0,52.210326,13.727780
REF/15,1807,0,52.199550,13.742880
REF/16,2711,0,52.188771,13.757979
DTM/0.000000,0.000000
CPH/0
WPX/3,677091.9699199299,36547.13066103124
6539.165156354323,599.2566170680447
-738.0571503307751,-412.6093069583932
-56.30524084059687,32.76212084486163
-1.542887633207162,-0.6848346983974403
WPY/3,1022036.486002622,20746.03598598863
10204.57187001487,-1373.069597637415
-1207.846949187127,-368.1470087566714
-58.47785895585847,72.28037702796101
-7.392278923720588,0.03592855592353315
PWX/3,13.71269724660935,1.670305315126525e-005
-1.944618120039353e-005,1.78172532918586e-019
2.628403177189398e-020,6.475483355430979e-021
-3.804557951106484e-023,-4.569603671992261e-024
-1.442204240733969e-024,-3.079676549370177e-025
PWY/3,52.22108814768813,-1.191641935323678e-005
-1.021697214024139e-005,-1.60684552939083e-012
-2.755367805347218e-012,-1.181206846131636e-012
-5.899876442852183e-020,-1.540740470699455e-019
-1.321332960406724e-019,-3.77790874438532e-020
ERR/1,0.000000,0.000000,-0.014764,-0.015171
ERR/2,0.000000,-0.000000,0.002197,0.000341
ERR/3,-0.000000,0.000000,0.006893,0.005676
ERR/4,0.000000,0.000000,0.001718,0.002545
ERR/5,0.000000,0.000000,0.008775,0.011744
ERR/6,0.000000,-0.000000,0.008907,0.010575
ERR/7,-0.000000,0.000000,0.002100,0.003598
ERR/8,-0.000000,-0.000000,-0.009231,-0.007454
ERR/9,-0.000000,-0.000000,0.006000,0.004592
ERR/10,0.000000,-0.000000,0.001124,-0.000661
ERR/11,-0.000000,0.000000,-0.005353,-0.007337
ERR/12,0.000000,0.000000,-0.011005,-0.013695
ERR/13,-0.000000,0.000000,-0.006609,-0.007000
ERR/14,0.000000,-0.000000,-0.004668,-0.003732
ERR/15,-0.000000,-0.000000,0.001025,0.002513
ERR/16,0.000000,-0.000000,0.012890,0.013467
PLY/1,52.140524,13.565808
PLY/2,52.111901,13.605810
PLY/3,52.189655,13.753589
PLY/4,52.218215,13.713541
PLY/5,52.140524,13.565808



regards

decnet
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[bdbcat]

decnet....

I'm not completely sure that we are looking at the same chart. Probably we are, since this header shows a scale of 35000, which is relatively large scale. The other chart shown in your previous image was probably much smaller scale, just by appearance. Also, I am not familiar with the geography here. I assume that the water should "connect" at the north-east end of Schmoldesee?

However, if we are looking at the correct chart, then I think the chart header is simply wrong. If the chart needs to be rotated to the right in order for it to show "north up" correctly, then it should have a non-zero skew parameter in the header.

Too bad the chart does not have a lat/lon grid to confirm our theory. Maybe you have other charts with similar display problems that have a grid for reference?

If indeed we are correct in our theory, then this is an issue to address with the chart publisher. OpenCPN can only respond to the information in the header, and assume it is correct.

Please let us know what you learn in your investigations.

Meanwhile, you may wish to remove this and similar charts from your collection. OpenCPN will not work correctly if the header (skew) is incorrect, even in Single Chart Mode.

Good Luck
Dave

[decnet]

Hi Dave,

The chart header i´nt wrong. I have tested the chart with Fugawi demo, the image I have attached. Fugawi find information in the chart to rotate it!

Can you tell me the function of the data in the header? or link.

All charts have a scale of 1:35000, this is standart for the river charts.


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[bdbcat]

decnet....

OK, lets not say "wrong", lets say "different."

The BSB chart header is very poorly documented. Most of what is known has come from various random internet postings, and some guesses.

What is clear is this:
The nv chart use of the parameter SK is clearly different from the US NOAA use of the same parameter.

It seems that nv wishes us to calculate the skew value ourselves, while NOAA kindly provides the correct skew value in the SK parameter.

Which is right? Who knows.

Using again NOAA as example, the US east cost ICW chart series is composed of large scale skewed charts. SK values are declared in the header to high precision, e.g. SK=299.9780556 OpenCPN uses the declared SK parameter to rotate the chart image for display, and this works out fine. So we have concluded that for this series that the SK parameter is accurate and meaningful.

At least for the nv charts, it seems that Fugawi must be calculating the skew value from the embedded georef solution. Hmmm....

OK, fine, we can do this. Our strategy should be:
"For BSB charts, calculate the apparent chart skew from the embedded georef coefficients. If the value differs by some percentage from the declared SK in the header, and the header declared value is identically 0.0, then adopt the calculated solution."

This strategy will allow us to understand that if the cartographer put a non-zero value in SK, they probably meant it to be used.

So, we will need to make a change to the NV PlugIn. This will not affect the OpenCPN core immediately.
You may expect to see an update to the NV PlugIn within a few weeks or so, but certainly not before the Release of OpenCPN 3.2 coming up shortly.

I'd still like to get the comments of nv-verlag regarding this issue. There is clearly a difference of opinion between them and NOAA on the meaning of SK.

Thanks for bringing this subject to the front.
Dave