Just joined this group, but have spent the past few weeks reading what great things are being done here! Using the info posted here, I have converted several charts
I have that are in an obsolete format. Here are my observations so far.
The following was taken from part of a finished .kap file:
BSB/NA=MyChart converted NU=X3,RA=3891,5586,DU=160
UN=METERS,SD=LOWEST ASTRONOMICAL TIDE
This is from a official NOAA chart:
BSB/NA=OLCOTT NEW YORK
KNP/SC=10000,GD=NAD83,PR=MERCATOR,PP=43.338,PI=0.500,S P=New York West,2000
DATUM 242.8 FT IGLD55 LAKE ONTARIO
A few comments.
1. SP= . Besides the above entry, I have also seen in this field the following: UNKNOWN,0
The value of 'UNKNOWN' does not appear correct. Most files contain just SP=,
2. Almost all 'real' bsb files I have looked at have values for PP= and PI=, PP seems to be the Lat midway on the chart and also printed on the chart after MERCATOR. Does anyone know what PI is? I know PP is 'Projection Parameter (value depends upon Projection) a.k.a. central meridian for Transverse Mercator Projections', but what does this mean?
3. When creating a .kap file using
tif2bsb [-c 127] chart.hdr chart.tif chart.kap
I have found that if the tiff file already has less than 127 colors, it is best *not* to use the -c parameter and let tif2bsb figure out how many colors are actually used in the pic. Using -c 127 will force tif2bsb to generate 127 RGB/ entries and the entry IFM/7. This added overhead creates larger .kap files due to smaller compression
taking place. One chart I converted was smaller by .5M when I did not use the -c parmeter.
4. I downloaded a .kap file that someone in this group created using mc2bsbh beta07. It will not open in The Capn (a commercial
pgm), however it will display on my homemade PalmOS BSBViewer pgm. Looking at the header, it was missing a few things: I added an OST/ entry, a CPH/ entry, changed UN=UNKNOWN to UN=METRES, and changed SD=UNKNOWN to SD=LAT (the later I am sure makes no difference). Still no luck getting The Capn to accept it ... actually, this .kap file crashes The Capn! The only thing left for me to try is looking at the color palette. This .kap file has 127 RGB/ entries and the graphics image uses all 127 entries (I know because I analyzed the bsb raster image). Perhaps this is what The Capn is upset about since it loads .kap with smaller color palettes.
I am quite sure this .kap file can be opened in OpenCPN
, but I do not have OpenCPN
running. My point in raising this issue is in order to create .kap files that are more towards the BSB standard format, whatever that is! ;->