The shoreline is simply a contour, the 0ft or 0m contour. The lake bed inevitably slopes up to it, either sharply, or gently. Whatever it does, I get as close as I can to the shore with the survey grid, and leave the rest to Dr Depth to interpolate. This way I end up with a pretty accurate idea of the nature of the shoreline. The craft I use for doing this has a draft of only inches, and a heavily protected prop (for rocky shorelines often I just use the oars)
Software needed for this exercise
GPSMapedit, you’ll need a registered version – its very good value for money
Globalmapper, this is not cheap software, but is REALLY useful .
Dr Depth, you’ve already got it or you wouldn’t be reading this…..
This method also works with Reefmaster
Create your shoreline in GPSMapedit using google maps. Correct the shoreline’s position (see my tutorial here). Save it in MP format.
Fire
up Globalmapper and open the mp file you have just created. Image 2
Edit
- Select all objects, then Right click
on one of the selected lines and select
Advanced feature creation options – create point features spaced along
selected feature. images 3 and 4
Sample
features at 2m intervals (this stops Dr Depth interpolating through the gaps
between). Image 5
Let
it do its rapid work, then go to Tools- control centre and uncheck the mp file
– leaving only the ”user created features” checked.
Now
export the file as a shapefile, selecting to export “points”. You have the
option to select the area you want to export on the “export bounds” if you need to. Image 10
Fire
up Dr Depth. File- Import/Convert and select your shapefile. It will be
converted and saved as a Dr Depth file. Now open the converted file. You now
have a shoreline – and all the islands etc…. image 11
Load
in your tracks, or database, and let Dr Depth do its stuff. Image 12 and 13
I
use a custom colour file to see my 5ft (shallows) and 10ft (caution) areas in
what is more or less chart format. Image 14
The
finished chart running in the chartplotter “OpenCPN”.
