"left" and "right" sides of glacier boundaries

[Georg Kaser]

Dear Bruce,

I would propose that a decission is not led by the demands of a certain 
method but should follow the convention that left and right in sciences 
related to the earth surface is defined as orograpically left and right. 
Look into the direction water (ice) flows and assign (the glacier 
boundaries) to either left and right. I would stick on this even if it 
makes the application of a given method more complicated.

Best wishes, Georg

Georg Kaser
-------------------------------------------------
Institut fuer Geographie
Innrain 52
A-6020 INNSBRUCK
Tel: ++43 512 507 5407
Fax: ++43 512 507 2895
http://meteo9.uibk.ac.at/IceClim/CRYO/cryo_a.html

On Thu, 24 Feb 2005, 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
>
> -- 
> Bruce Raup                                               Phone:  303-492-8814
> National Snow and Ice Data Center, U. of Colorado, 449 UCB, Boulder, CO 80309
> http://cires.colorado.edu/~braup/
>