Originally Posted by HappySeagull
I had to Disable
Quilting to get my versions to zoom out a lot ...With Quilting ON
switched to CM93 after zooming out to 162700 on my 1024x laptop screen
It will depend on which other charts you have loaded in O...?
Here is scale 80000,(image size 7360x5699) and zoomed seems to have adequate detail.
BSB/NA=Saint Thomas to Anegada (Virgin Islands)
hope that helps...?
Switching off quilting and adjusting the DU value had no effect for me, and I ran out of time to experiment
more before I had to leave for BVI. But I was able to use the NGA charts even with the zooming problem, and they were much more accurate than NOAA #25641.
After I returned from BVI I did some more experimentation, and discovered that after upgrading to OpenCPN
3.1.13x9 beta, the behaviors that you described happened. Before that I was using 3.0.2, which appears to behave differently. With 3.1 beta, turning off quilting allowed zooming way out, just as you show.
One other change I made was to reduce the size of 25609 by 50% (like you apparently did), and that allowed for zooming out further than before with quilting on. Apparently with quilting on, OpenCPN has a limit to how far it's willing to condense pixels before going to a different chart, and reducing the chart size in a photo
editing program helps to overcome that limitation (at the expense of some resolution). However, I suggest that reducing the size of the chart should be accompanied either by a proportional reduction in DU or proportional increase in SC. IIRC, the DU value is automatically calculated in the KAP file utility from SC and the calibration data when it generates the .hdr file, so I think it's best to set SC in the CHARTCAL.DIR file prior to generating the .hdr file, and let the KAP utility calculate DU. I'd be concerned that manually tweaking DU in the .hdr file might cause something else to break.