Applying Notices to Mariners (NTMs)

[PjotrC]

Richard...

In many cases it would be easy indeed to set the right icon to an NtM mark, but I think the full-size icons should be displayed at the appropriate chart scale only... Lines and areas perhaps can be handled in general...

The marks I am showing can only be interpreted as "Careful here, more info in this NtM..." They can not be considered "Chart Corrections". The text of an NtM can only be interpreted in the context of an appropriate edition of the base chart (up to date to the previous NtM), which is not part of the picture here, and only will be if we could learn at run time what is currently on screen.

Reading NtM text only will never produce an updated chart:

- chartlets and Notes are separate and difficult to treat
- New Editions cancel all history, so without a N.E. original no corrections should be applied at all
- only one scale (and even - one chart) should be considered at a time (see pictures below)
- if two or more correction points overlap exactly, OCPN WPT mechanism will not show "Additional Info" for the older/newer ones, which can still be valid
- some NGA NtM syntax is hard to parse
- some corrections are not related to any point on chart

So, with this approach one can only aim at an approximation of the process (undoubtedly useful).

Piotr

PS.

If perhaps Santa would drop into my mailbox a link to a .csv DOLE document (Dates Of Latest Editions, preferably with numbers, titles, scales and chart extent limits) for all NGA charts...

NOAA publishes one for its 1000 domestic charts, but NGA (NIMA) only publishes this in a full catalog, hard to convert into .csv.

British Admiralty publishes an .xls for the dates, titles and scales (Chart Availability List).

[PjotrC]

I have uploaded to nga_ntm_demo.zip - 4shared.com - online file sharing and storage - download a demo kit with .gpx layer files generated automatically from NGA Notices for Region5 and the sample Folio, ca. 8000 correction points.

Before putting more work in it is probably good to review and comment.

It works well and reasonably fast in OCPN, as long as no List Contents is clicked in RM, what takes some minutes. The parser is quite naive, but I believe not much more can be done... the list of issues I mentioned in previous post remains valid...

I put some keywords into WP Descriptions to readily show what the Notice is about, but a full keyword in WP name clutters the screen too much - so a first letter only in the name... (D - Depth, W - Wreck, etc..)

The files for points and lines+areas are separate, they can go into separate layers or be loaded all together.

The sample NtM database is linked to at E:\nga_ntm. I do not know how to make Notepad use relative pathnames, so all the links may have to be changed for some users. (Would be nice to have all the WP links point to the portable drive for 2.6. -p, but how?)

P.

[nohal]

Originally Posted by PjotrC

If perhaps Santa would drop into my mailbox a link to a .csv DOLE document (Dates Of Latest Editions, preferably with numbers, titles, scales and chart extent limits) for all NGA charts...

Pjotr...
Would NGA Charts project stats be the type of info you like? If so, Santa will export it for all the charts as CSV in a couple of minutes...

I agree with you that you are hitting the limits of the navobjects mechanisms in OpenCPN both technically and from the usability point of view. Robbing some of Dave's code and gluing it together with SpatiaLite download page perhaps should not be impossible in a reasonable time.

Pavel

[PjotrC]

Originally Posted by nohal

Would NGA Charts project stats be the type of info you like? If so, Santa will export it for all the charts as CSV in a couple of minutes...

Dear Santa...

Yess, thanks, please...

Much obliged,

Piotr

PS.

Test status update:

I pulled down all NtMs for all regions for 2011 (20000+ correction points, it all fits). A couple of glitches, but very useful overall.

[nohal]

Pjotr...
Here you go, let me know if the format and special characters escaping suits your expectations.
If you prefer the raw data, there's a daily dump of the NGA project database available at https://github.com/ngacharts/data - the CSV is a dump from the view at https://github.com/ngacharts/ngachar...tabase.sql#L94

Pavel

[PjotrC]

Originally Posted by nohal

let me know ...

Pavel,

Thanks, the file is readable OK. Is it possible to have the bounding rectangles (lat, lon rather than pix) for the charts?

P.

[cagney]

Piotr
Seems like Pavel is off for a while...
Have a look at columns AM, AN,AO and AP (after import into a spread sheet) which ought to be what you are looking for. The headings are South, West, North, and East.
Thomas

[PjotrC]

Magic...

How did you do it? They were not there yesterday... :-) I hope they stay...

P.