Charts

[fgd3]

I downloaded the Caribbean charts and confirmed there are no soundings or other underwater features. It's hard for me to see how they could be of any use for navigation.

Fabbian

[rgleason]

What we need is crowd sourced depth recordings that can be uploaded. The survey plugin might be an assist, but it will take a long time.

[Tupaia]

Originally Posted by nohal

Tupaia...
KAP chart is nothing else but a TIFF with 2-127 color palette and a text header describing the chart and it's calibration. Starting with a PNG, you will not get a 100x smaller chart file, neither starting from PCX you get a 12x smaller chart file than if you start with a TIFF.

snip

It would be a bit easier to suggest an "optimal" way to handle your chart portfolio if we could have a look at one of your PCX files...

Pavel

Hi Pavel, I have had some more time to devote to this now.

I found a description of the process in an xls file that was given to me but it is very out of date.

The process so far - I am now working with an original .jpg that I have downloaded that has known reference LAT/LON to test the process. I am still having some issues that maybe more informed members could fix.

1. Copy original .jpg to working directory "Chart Conversion"

2. Use a program JpegOpt to compress the file. The link to this appears to be broken so have not managed to download it. Do I really need to do this? I chose a small file 200kb to start with so ignored this for now.

3. Used Gimp2 to reduce the colours to a palette (16) and produce .png & .tif files.

4. Used Map Cal II to generate geo-reference co-ords in a .dir file.

I now have:
ROU6.jpg - original
ROU6.jpg - working file (should be compressed see note above)
ROU6.png
ROU6.tif
ROU6.dir

The header .dir looks like this.

[ROU6.PNG]
NA=Coronilla
FN=ROU6.PNG
GR=0
PY=1
QU=0
SC=30000
BC=4
B1=-33.9195700516832,-53.5175567010309
B2=-33.9538655635017,-53.5175567010309
B3=-33.9538655635017,-53.4523195876289
B4=-33.9195700516832,-53.4523195876289
CC=2
C1=67,66,-33.921666666667,-53.515000000000
C2=1522,939,-33.951666666667,-53.455000000000
GD=WGS84
NU=ROU6
PR=1
DS=0,0
WI=1592
HE=1008
DX=3.81
DY=3.81
LAT0=0
LON0=0
DT=0
LATS=0
LATN=0
DU=1
PC=0

When I try to run imgkap I get invalid header type ROU6.DIR

Any ideas where I am going wrong.

Once I have it achieved conversion. I think it would be good for me to write a simple procedure with an example that others can use.

Peter