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).
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).