Depth soundings in vector charts

[eduardopeloso]

Hi, everyone!

I need to find the place in the OpenCPN source code where the depth soundings are read from the vector chart to be then displayed. I suppose lat/lon is also read in the same place, because this information is necessary to know where to display the value... :P

Can anyone help me here, please? The source code is huge, very complex, and someone who is more involved with its development will probably already know this, or at least be able to find it much quicker than I.



Thanks.

Cheers.

[did-g]

Originally Posted by eduardopeloso

Hi, everyone!

I need to find the place in the OpenCPN source code where the depth soundings are read from the vector chart to be then displayed. I suppose lat/lon is also read in the same place, because this information is necessary to know where to display the value... :P

Can anyone help me here, please? The source code is huge, very complex, and someone who is more involved with its development will probably already know this, or at least be able to find it much quicker than I.



Thanks.

Cheers.

Hi,
search for geoPtMulti or mps in source code.
What are you trying to do?
A lot of OpenCPN code for reading vector charts is from a project named gdal, working with this project code could be easier.

[eduardopeloso]

Thanks, did-g!

I need to extract lat/lon and depth value for all soundings in the chart into a text file.

Perhaps it would be best to try to get the code from gdal. I'll try to find it.

Cheers.

[eduardopeloso]

did-g:

This one? GDAL: GDAL - Geospatial Data Abstraction Library

[did-g]

Originally Posted by eduardopeloso

Thanks, did-g!

I need to extract lat/lon and depth value for all soundings in the chart into a text file.

Perhaps it would be best to try to get the code from gdal. I'll try to find it.

Cheers.

There's a copy on github .
For batch jobs gdal should be easier, sounding in s57 standard is a bit weird.

First time Opencpn open a S57 chart it converts it in an internal format Osenc.

A hack in opencpn would be to add your export for sounding in:
Osenc::CreateMultiPointFeatureGeometryRecord200

I don't remember if you can get sounding not of MultiPoint type.

[bcn]

And you will get the soundings only for plain S-57 charts by this way.
Neither for S-63 nor for oeSENC data.

[bdbcat]

eduardo...

Don't know exactly how you want to extract the depth data, whether directly from the S57 cell, or during OCPN runtime with a simple printf....

If the former, GDAL may be best. There is a Python interface that may make life simple.

If the latter, consider:

s52plib.cpp:
int s52plib::RenderMPS( ObjRazRules *rzRules, Rules *rules, ViewPort *vp )

Here you will see how OCPN Feature objects encode depth and lat/lon for multipoint soundings.

Good luck
Dave

[ivica]

I guess this is quite old post, but I will give it a try.

This is quite interesting for me as well, as I want to improve my ocean model in coastal waters and ENC are amazing source of info, much better then official topo charts like ETOPO, GTOPO etc.

Does anybody know about python or whatever tool that is capable of extracting SOUNDINGS from CM-93 v2 into something like shapefile, txt, whatever I could load into arcgis or python?

Haven't seen any post after, possibly Eduardo managed to extract the info?

Thanks in advance!

Regards,
Ivica

[rooiedirk]

I did it once, but deleted the code. However I think it was here.

[rooiedirk]

Can't edit the above post anymore, but if I add the line

printf("%f  %f  %f\n", lat, lon, depth);

in the position mentioned above I get an output like this.

52.634856  5.578131  4.100000
52.664151  5.580425  2.100000
52.660552  5.589875  0.800000
52.649258  5.607020  3.800000
52.634812  5.609590  4.200000
52.638594  5.553924  5.200000
52.644127  5.542943  4.700000
52.663117  5.525708  4.500000
52.663297  5.548883  5.000000
52.660734  5.498841  3.000000
52.636885  5.487185  3.900000
52.636792  5.505277  3.600000
52.629727  5.522335  2.900000
52.649440  5.514683  2.800000
52.666537  5.510046  4.200000

Latitude, Longitude and depth.

[Baksteen]

For S-57, you can use GDAL's ogr2ogr. Not sure how to deal with CM-93, I don't have a copy of those.

ogr2ogr -f "[filetype]" -oo SPLIT_MULTIPOINT=ON -oo ADD_SOUNDG_DEPTH=ON [output] [input] SOUNDG

For example:

ogr2ogr -f "geojson" -oo SPLIT_MULTIPOINT=ON -oo ADD_SOUNDG_DEPTH=ON soundings.geojson 1R76W7RI.000 SOUNDG

Check the ogr2ogr documentation for supported vector formats.