Chart Header Modification

[turtleback]

I have loads of kap charts with an 'UNKNOWN' entry for the 'projection (PR=) type. Is there a method of just modifying the header data for the chart file? I need to change 'PR=UNKNOWN' into 'PR=MERCATOR' so that openCPN 4 will read the charts.

I have tried a simple text editor but it corrupts the data when the changes are saved.

Cheers. John

[nohal]

John...
Make sure the editor does not change the binary part of the chart (Notepad or wordpad on windows = not good, any other editor = most likely good)
After editing the header, you MUST fix the index table using bsbfix (If you are using Windows, get it from libbsb - Read, Write and Convert BSB charts, if you are using Linux, it is packaged in the Official OpenCPN PPA)

Pavel

[HappySeagull]

actually O4 will open UNKNOWN charts.
See? (click the picture to see it better)



so try just bsbfix...and by the way, it seems to work fine (in XP anyways) to just drag the chart file onto bsbfix.exe...put a copy in your chart folder and try it...one at a time only this way.

You need be careful calling them MERCATOR alright because first off, it has more characters than UNKNOWN -8 vs 7 letters- and that will be an issue that I think bsbfix can fix , but you and WE are all better off without blithely copying mercator in if there's any chance you are going to share these charts.

[turtleback]

I take your point on blithely adding Mercator but they are Mercator projection so it would be better to add it in if possible. I can't get O4 to open a kap chart that has an UNKNOWN projection. It will open a kap chart with an UNKNOWN datum as your example shows but I don't have a problem with the datum only the projection.

[nohal]

turtleback...
Missing projection is of course a critical issue. bsbfix will technically fix the charts you modify manually. If they still won't open, there is a critical issue with the calibration data and you can find the reason in the logfile. If it won't be clear, we need to have a look at one of them.

Pavel

[HappySeagull]

ahSorry! inattention on my part.
But I did do the experiment by changing a chart to UNKNOWN in "notepad++" (losing a character! and I use ANSI because it seems native to the headers?...) ) and then change it back to MERCATOR , dragged it onto bsbfix and it worked....
I know a way to edit bunch at a time in freeware Notepad++ using the macro function or find+replace in ALL but there is probably a better way in some hexeditor capable of editing a bunch at a time so bsbfix might not be required but I haven't troubled to find it yet...