[OSM-talk] New tool: Generate coastlines from Landsat imagery

Darryl Shpak darryl at shpak.ca
Sun Aug 5 04:14:40 BST 2007


Brent Easton wrote:
> Hi Darryl,
>
> Very nice tool, but it is not possible to map coastal lakes connected to the sea on the East coast of a continent.
>   
Yup -- it'll wander off to sea and merrily trace the shoreline. Not so 
much a bug as an undesirable feature :)
> I you just need a couple of extra parameters to
>
>  a) Select the inital search to be East or West (or South or North?)
>  b) Select to trace Clockwise or anti-clockwise once landfall reached.
>
>   
They're both on my todo list. For the second one, you need to be careful 
that you always create the segments in the right direction, regardless 
of which direction the trace was made in. I'm just looking at the code 
now, and changing the initial search direction is actually going to be 
pretty easy. I'll try to get that done this weekend (which includes 
Monday -- it's a long weekend here).

As a cheap hack, you can open up the PNG file that gets downloaded from 
Landsat, paint a blockade across the piece that's giving you trouble, 
and run it again.

I'm trying to figure out a generic way of getting it to trace a lake 
without wandering down all the attached rivers, but haven't come up with 
anything yet.

Thanks for the feedback!

- Darryl (DShpak)





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