"left" and "right" sides of glacier boundaries

[Gordon Hamilton]

Georg is correct. Handedness is a well-defined term in hydrology, so we should stick with convention. There is one potential problem with this approach -- the direction of flow needs to be known in order to assign handedness, and that information might not be available, or might be difficult to determine, for remote unexplored regions. I think we could make reasonable guesses in most situations, though.

-gordon


Bruce Raup wrote:
> Hi all,
> 
> As you probably know, the GLIMS database provides for storing information
> about what materials and features are on the left and right sides of
> glacier boundary segments, and the GLIMSView program makes it fairly easy
> to assign such attributes to digitized glacier boundaries.  However, the
> definition of "left" and "right" hasn't really been firmly specified.
> 
> Ultimately, it would be nice if in GLIMSView, you could just click on one
> side or the other and not worry about whether it is "left" or "right".
> But we're not there yet.
> 
> I propose the following solution.  Since it might negatively impact those
> who have already assigned such attributes, I want to get your feedback.  I
> propose ordering all polygons to be in counter-clockwise order (interior
> on left) at ingest time.  References to left and right would be according
> to this vertex ordering.
> 
> GLIMSView currently outputs polygon segments with points ordered in the
> direction of digitization, and can therefore output segments with
> inconsistent direction when placed within the polygon.  My ingest software
> already puts the segments together so that they match up end-to-end in a
> consistent direction.  Now I'd like to make the handedness consistent too.
> 
> Comments?
> 
> Bruce
> 




-- 
 Gordon Hamilton, Asst. Professor

 Climate Change Institute
 University of Maine, Orono, ME 04469

 gordon.hamilton at maine.edu
 207-581-3446 (ph/voicemail)
 207-581-1203 (fax)